High velocity is achieved through adiabatic expansion of motive steam across a convergent/divergent steam nozzle. Having the higher expansion ratio will cause the foam blanket to last longer or not break down as fast, preventing the need to reapply as often and reducing the amount of water and concentrate needed. 5 and for a range of nozzle pressure ratios. CD nozzles, e. It is found that the nozzle expansion ratio, particle size, accelerating gas type, operating pressure, and temperature are main factors influencing the accelerating behavior. p c = critical pressure (Pa) p 1 = inlet pressure (Pa) n = index of isentropic expansion or compression - or polytropic constant. The most commonly used nozzle is the de Laval nozzle, a fixed geometry nozzle with a high expansion-ratio. Expansion Ratio The expansion ratio of the nozzle is the ratio of exit area to throat area. 068 MPa the mass flow rate is 0. With a variety of brands to choose from, you can find the precise foam firefighting equipment for your department's needs. In other words, the hot gases created by burning fuel inside a jet or rocket engine are exhausted through a nozzle to produce thrust. Here the idea is to use the short inner nozzle at low altitudes, and deploy the outer extension at high altitudes, so that the expansion ratio is more nearly ideal at all operating conditions. The study is about a supersonic jet flow (perfect expansion), from a C-D Mach 2. Nozzle models inviscid, adiabatic and hence isentropic flow of a calorically perfect gas through variable-area ducts. Changing the powder charge does not change the expansion ratio, however. Equations for C -. Preliminary engineering report for design of a subscale ejector/diffuser system for high expansion ratio space engine testing. Synonyms for nozzle in Free Thesaurus. The nozzle cone exit diameter (De) can now be calculated. MID-EXPANSION - Expansion ratio from 20:1 to 200:1. The relative cost is low. The valve body turns extremely cold to the point ice accumulates. 2:1 Turbine exhaust is ducted through a swiveling nozzle to provide Stage II roll control. The selection of an optimum nozzle shape for a given expansion ratio is generally influenced by the following design considerations and goals: (1) uniform, parallel, axial gas flow at the nozzle exit for maximum momentum vector, (2) minimum separation and turbulence losses within the nozzle, (3) shortest possible nozzle length for minimum space. Effects: 1. The all-axis gimbaling capability is 8 degrees. With an expansion ratio of 1700:1, 0. Baseline operation was at a mixture ratio of 5. It can be computed from P0 -- p[1 The and and. The best Nozzle Pressure Ratio (NPR) values are found to be 24. 202 Elements of Heat Engines Vol. This study reveals that the addition of a nozzle to the PDE combustor has the. A polyester mesh bag with mesh openings of 0. - The steamhas a very high velocity at the end of the expansion, and the enthalpy decreases as expansion takes. The flow velocity gradually decreases afterwards. 8 grains of water, I use 30. Expansion Ratio The expansion ratio of the nozzle is the ratio of exit area to throat area. 0021, about 1 to 500. The Optimum Rocket Nozzle Expansion Ratio: An Air – to – Air Missile Demonstration. HTPB propellant. The peak efficiency of a variable geometry turbine occurs at about 60% nozzle opening. Sutton [1]). Experimental and Numerical Study of Jet Mixing from a Shock-Containing Nozzle For a nozzle with a given expansion ratio, the range of nozzle pressure ratios over. The expansion ratio also allows the nozzle designer to set the exit pressure. In actual, as the gas expands, the ratio shifts due to the changes in temperature and the chemical composition. Nozzle expansion conditions •Three cases are possible: 1) p e < p a → over-expanded nozzle 2) p e = p a → adapted nozzle 3) p e > p a → under-expanded nozzle •In cases (1) and (3), pressure adjusts to ambient conditions through shock waves outside the nozzle •For a given nozzle geometry, thrust is maximum when nozzle is adapted. moen, capt, usaf. In this case, the pressure pe and pam can be different corresponding to pe > pam or pe < pam in dependence on the nozzle expansion ratio. Assume the intersection of the centerline and the exit plane of the nozzle is the origin of our coordinate system. Each nozzle has a ball shut-off valve. The ratio of the nozzle total to static pressure ratio is called the nozzle pressure ratio NPR. Rockets depend for their action on Newton's Third Law of Motion that: "For every action there is an equal and opposite reaction. The expansion ratio is the amount of finished expanded foam that will be produced using the correct nozzle. Specific impulse: 303 s vacuum. Thrust: 42. Nozzle expansion ratio increased from 9. Certain results obtained from a thermodynamic analysis of the ejectors have been confirmed in a wide range of geometrical. 9"), this means the sea level Merlin has an expansion ratio of 16:1 while the Merlin Vacuum engine has an expansion ratio of 164:1. For faster chamber pressurization a sacrificial erosive nozzle can be cast in the choke. See also Steam Turbine Nozzles. However, efficiency drops off rather quickly as nozzle opening is reduced or increased from a mid-vane opening position, Figure 3 [2641]. Flow of steam through nozzles: The flow of steam through nozzles may be regarded as adiabatic expansion. 2b), until eventually the isentropic case, curve f, is reached If the receiver pressure is below the third critical point, an expansion takes place outside the nozzle. Mach number Nm is the ratio of the gas velocity to the local speed of sound. O/F ratio: 1. The appropriate expansion is necessary to avoid the under-expansion or the over-expansion. The Mach number at the nozzle exit is given by a perfect gas expansion expression P c is the pressure in the combustion chamber and P atm is atmospheric pressure, or 14. nozzle-expansion ratio; nozzle-mix gas burner. Ho we ver,. The expansion ratio is the amount of finished expanded foam that will be produced using the correct nozzle. The convergent parts of the nozzle are sharp and frictionless. All of our foam equipment is designed with safety and ease-of-use in mind for quick fire suppression during any emergency. Under these conditions, the nozzle is said to be choked and the nozzle outlet pressure remains at the critical pressure. We made converging-diverging rectangular nozzle with expansion ratio of 6. Foam is then produced, with a normal expansion ratio of 1:4, depending upon foam. High expansion ratio PSU foam has been prepared by using a new kind of PSU foaming method with scCO 2 as foaming agent assisted mold pressing. A typical section through a flow nozzle is shown in Figure 49. The highest possible velocity of argon gas at the nozzle exit is? Someone that is good at solving these problems, need help. HTPB propellant. The effective exhaust velocity V e is a function of the nozzle geometry such as the nozzle expansion ratio A e /A t. The results indicate that an increase in specific impulse obtainable with an increase in. For faster chamber pressurization a sacrificial erosive nozzle can be cast in the choke. In practice, this is more than good enough for the intended purpose of the program. concluded that contour nozzle gives a greater expansion ratio compared with a conical nozzle. Each of these allows the supersonic flow to adapt to the ambient pressure by expanding or contracting, thereby changing the exit ratio so that it is at (or near. Constant chamber pressure throttling of an expansion-deflection nozzle. By adding the TFT nozzle attachment for foam operations, the expansion ratio is 8 to 1. In Mollier Chart, 1 -t- 2′ is the actual expansion of steam through nozzle. Velocity Co-efficient is square root of the nozzle efficiency when the inlet velocity is assumed to be negligible. produce relatively low expansion ratio foam while those designed for increased expansion ratios have shorter discharge distances. [ICEM] Aspect Ratio, Mesh Expansion Factor -- CFD Online Discussion Forums [ Sponsors ]. These area ratios correspond to a pressure ratio (chamber-to-ambient) of 1000 (for the downstream contour) and 148 (for the upstream contour). Example - Orifice Flow. Changing the powder charge does not change the expansion ratio, however. For now, we will accept that conversion of water to steam results in a 1700:1 expansion ratio (a later post in this series will explain why). Mostly class B fires Medium expansion- ratio of 20-1 to 200-1 through hydraulic operated nozzle 30-1 and 55-1 for hazardous materials High expansion - ratio of 200-1 to 1000-1 typically confined spaces. The alternative approach, which leads to nozzles of the plug type, is examined in some detail below. In vacuum, all flaps would be closed for maximum >expansion. The expansion factor Y depends on the specific heat ratio χ , the diameter ratio β and the ratio of downstream and upstream absolute pressures. The study recommended that conical nozzle be used at sea-level and that the contour nozzle be used at higher altitudes since for a given nozzle length, greater expansion ratio is required at higher altitudes [5]. 174 ft/sec2 he exit height of nozzle (see fig. In all cases, the ratio of inlet total pressure to exit static pressure, which is called nozzle pressure ratio, are set to be 7. • When possible, ε is selected so that P e = P a and the engine operates at optimum thrust. • When the number of full range pressure cycles is greater than 7000 and the nozzle is subject to external loads. Hand Monitors. And we can set the exit Mach number by setting the area ratio of the exit to the throat. Let us discuss about the Conical nozzle and bell nozzle. Additionally, it produces a foam blanket which provides an insulating barrier between the fuel and air. ratio of the actual thrust coefficient in a vacuum to the ideal that defined the same values of the mixture ratio (2. ε= ∗ (2) A rocket generally does not travel through a single altitude, thus while designing a path over which a rocket is to travel is considered so that the expansion ratio that maximizes the performance is selected. In really the mass flow rate is a constant and equals m * from point ε * c to an expansion to vacuum ε c =0. Product features • All stainless steel body and bronze nozzle • Low weight • Easy to install • Large area coverage • High capacity, up to 60m3 foam/min • Expansion ratio is 667:1 Enquiry Now. EXPANSION. expansion ratio (assume conical nozzle with 15. Since both engines have the same throat of 226mm (8. Each of these allows the supersonic flow to adapt to the ambient pressure by expanding or contracting, thereby changing the exit ratio so that it is at (or near) optimal exit pressure for the corresponding altitude. 200", it says the expansion ratio is 9. For faster chamber pressurization a sacrificial erosive nozzle can be cast in the choke. The sampler consists of an expanding nozzle, a sample bag, and a wading rod assembly. The only existing test that must be passed by a hand-held carbon dioxide extinguisher is. For example, if an air-aspirating nozzle draws in nine units of air for each unit of foam solution discharged, this equates to a 10:1 expansion ratio of finished foam to foam solution. This research consists of a base line test of the factory nozzle, as well as testing of three 15-degree conical nozzles with different expansion ratios. Looking for nozzle-expansion ratio? Find out information about nozzle-expansion ratio. Optimum flow rate. A series of interchangeable nozzle inserts gave expansion ratios of 2, 3, 4, 6 and 10. High expansion ratio PSU foam has been prepared by using a new kind of PSU foaming method with scCO 2 as foaming agent assisted mold pressing. PY - 2007/10/1. I must caution you that the nozzle type alone will not determine the final application rate. Chamber temperature 4200°F j. 85 mm Nozzle End Diameter (inner) 35 mm Nozzle Expansion Ratio (by area) 150 Mass, Thruster with Valve 350 g (single seat) 650 g (dual seat) Chamber Nozzle Material Platinum/Rhodium. The worksheet output image for this group is given in Figure 1. I'm talking expansion nozzles like the valve on a SCUBA tank for example. ) The relatively stagnant region in the center of the nozzle can possibly be used for installation of gas generators, turbopumps, tanks, auxiliary equipment, and turbine gas discharges. The peak efficiency of a variable geometry turbine occurs at about 60% nozzle opening. Nozzles synonyms, Nozzles pronunciation, Nozzles translation, English dictionary definition of Nozzles. It is a reversible adiabatic. Standard Nozzles. Antonyms for nozzle. A projecting part with an opening, as at the end of a hose, for regulating and directing a flow of fluid. The nozzle converts the slow moving, high pressure, high temperature gas in the combustion chamber into high velocity gas of lower pressure and temperature. Corundum, sintered. All of our foam equipment is designed with safety and ease-of-use in mind for quick fire suppression during any emergency. 5) and combustion pressure in the chamber (2. • Can use variable expansion ratio nozzles -extendable, two-step nozzles e. The study recommended that conical nozzle be used at sea-level and that the contour nozzle be used at higher altitudes since for a given nozzle length, greater expansion ratio is required at higher altitudes [5]. p c / p 1 = ( 2 / (n + 1) ) n / (n - 1) (1) where. ber, the nozzle losses were sufficiently large to result in measured thrust coefficients. You'd get the extra thrust of solids, while getting a better mass ratio overall, and much better Isp on that core engine. Mach number is the ratio of the gas velocity to the local speed of sound. The viscosity effect is high. An example for a suitable apparatus is given in document ISO 7203-2. Amongst the variations are: a) Extendable nozzles. Expansion Factor. instability of the separated ﬂow in convergent–divergent nozzles of moderate expansion ratio. Plot both minimum Length and RS-27A Contours … ii) Calculate and plot design Aerospike spike contour of same expansion ratio as RS-27A NOZZLE … iii) Calculate design altitude for this expansion ratio and plot design Mach. When its value decreases beyond this value, the fl ow maintains a constant value. 5 kilometers per second can be obtained in rocket nozzles. Core stage engines with an operation time of up to 10 minutes feature a medium-range expansion ratio, whereas upper stage engines. A typical section through a flow nozzle is shown in Figure 49. 395 m 3 of steam at 100 o C (212 o F) (see Figure 6) Figure 6. Bronze, Aluminum. Each device will produce a specific foam quality, such as finished-foam expansion ratio and foam blanket 25 percent drain time. 95 GPM (360 LPM) Foam Aeration Nozzle Akron Brass' Foam Aeration Nozzles are designed to increase the fire or vapor suppression effectiveness by optimally enhancing the foams air aspiration. The objective of this work is to develop guidelines to identify the optimum nozzle geometry that maximizes critical pressure ratio while minimizing pressure drop across the nozzle. not put into the formula. Expansion can happen in two ways, similar to compression. Results show that the extent of influence of the expansion ratio depends on the densimetric Froude number, grain size of the bed material and tailwater conditions. The required upstream diameter is 10 to 30. For about $5,000 to $10,000, foam rigs can be outfitted with a “fault-interruption ratio” (when the mix goes off ratio, the rig shuts down) and a temperature monitor and will also produce printouts as proof of proper ratio. The nozzle expansion ratio of each booster beginning with the STS-8 mission is 7-to-79. reaction-control / analysis / nozzle_scripts / nozzle_sizing. SNPE solid rocket engine. • Medium expansion nozzles. Define Nozzles. See also Steam Turbine Nozzles. The exit static pressure of the exhaust jet depends on the chamber pressure and the ratio of exit to throat area of the. Experiments were conducted in a facility with 1. 25 mm is attached to the rear of the nozzle assembly with a rubber “O. 0 and WRC 107 or 297 is considered for use. The viscosity effect is high. Baseline operation was at a mixture ratio of 5. The expansion nozzle contour designed by this method has. The relation between expansion ratio and pressure ratio can be found from mass conservation and the isentropic relations:. At high altitudes, the aerospike nozzle is able to expand the engine exhaust to a larger effective nozzle area ratio. CFD: Super Sonic Diverging Rocket Nozzle CFD Solver: Ansys Fluent Chamber Pressure: 50 bar Chamber Temperature: 1200 K Nozzle Angle: 15 deg Nozzle Expansion Ratio: 9. Ratio of specific heats (. 1) and the geometric expansion ratio nozzle. However, efficiency drops off rather quickly as nozzle opening is reduced or increased from a mid-vane opening position, Figure 3 [2641]. A stream of foam solution is sprayed at high speed to an expansion net, drawing into the body the air required and producing foam with an expansion ratio of about 1:20. With this kind of expansion ratio for this engine, the nozzle flow is not over expanded. The expansion ratio, nozzle cross sectional area at exit divided by area at. In variable nozzle geometry turbines (VNT), the vanes that form the nozzle are opened to control turbine mass flow and expansion ratio (ER) in order to allow better engine matching and the generation of more turbine power. nozzle expansion ratio (ratio of the nozzle exit area A e to the nozzle throat area A t) in the range A e/A t#1y2. This research consists of a base line test of the factory nozzle, as well as testing of three 15-degree conical nozzles with different expansion ratios. The nozzle losses, as determined by the difference between the one-dimensional isentropic thrust coefficient and the measured thrust coefficient, were correlated in terms of the throat Reynolds number and nozzle area ratio. 89 times the ambient pressure. Expansion 5 Δpressureavailablefor Turbine Exit Pressure 5 T Combustor Inlet Ambient Pressure pressure available for expansion across Exhaust Nozzle 0 2 1 h W P =Δ Note: 1) Flight Mach = 0 2) P =P Compression 3 Lines of Constant Pressure 2) P t2 = P amb 3) P = power 4) W = mass flow rate 5) h 0 = total enthalpy 2 Compressor Inlet 6 S. Let us discuss about the Conical nozzle and bell nozzle. expansion ratio foam while those designed for increased expansion ratios have shorter discharge distances. Each nozzle has a ball shut-off valve. In actual, as the gas expands, the ratio shifts due to the changes in temperature and the chemical composition. The gas properties have an effect as well. Ratio of the cross-sectional area for gas flow at the exit of a nozzle to the cross-sectional area available for gas flow at the throat Explanation of nozzle-expansion ratio. HIGH EXPANSION FOAM: Expansion ratio above 200 to 1. Carbon - diamond. However, the flow is deflected by a plug, or centerbody, that forces the gases away from the. A projecting part with an opening, as at the end of a hose, for regulating and directing a flow of fluid. 3 baseline (no step) case is shown in Fig. 1 Notable is the low expansion ratio of booster engines due to the comparable short duration time. The maximum expansion ratio (MER) refers to the biggest expansion ratio of a round section before bursting when hydrobulged at any one time without any preforming; this is an important value that can illustrate the standard of manufacturing techniques of tubular parts with changeable diameters. 65 Mixture Ratio Range 1. Specific heat ratio 1. It can be easily removed in seconds for a water-only or non-aspirated stream. Chen et al. A projecting part with an opening, as at the end of a hose, for regulating and directing a flow of fluid. Before describing the various forms of annular nozzles, it is useful to mention some key differences in design parameters from the conical or bell nozzles. For example, if one gallon of foam solution enters the nozzle and 50 gallons of bubbles exit the nozzle, the expansion ratio is 50/1. Marshall A thrust augmented nozzle for hybrid rocket systems is investigated. The only specific answer I've found so far is: "Rocket engine - Wikipedia, the free encyclopedia For efficie. Design the nozzle expansion ratio using the compressible flow equations. In other words, the hot gases created by burning fuel inside a jet or rocket engine are exhausted through a nozzle to produce thrust. Engine nozzle has an ablative extension that increases it's expansion ratio from 13:1 to 49. The expansion area ratio for a traditional nozzle has already been discussed. Fixing all other variables (primarily the chamber pressure), there exists only one such ratio that optimizes overall system performance for a given altitude (or ambient pressure). Answers: 0. Mach number is the ratio of the gas velocity to the local speed of sound. 0%, provides for longer surface wetting with reduced risk of ignition/re-ignition. GAM7 specific heat ratio of exhaust gas at nozzle entrance jet location where exhaust flow has expanded to ambient pressure M9 nozzle exit Mach number based on nozzle expansion ratio Mjet fully expanded jet Mach number Mach Mach number Meas measured NPR nozzle pressure ratio (P8 / Pamb) N1 fan rotor speed, rpm N2 core rotor speed, rpm OH. Let us discuss about the Conical nozzle and bell nozzle. #: eps = Nozzle Expansion Area Ratio #: frozen flag, 0=equilibrium, 1=frozen #: frozenAtThroat flag. This parameter reduces the overall efficiency and work output. p c / p 1 = ( 2 / (n + 1) ) n / (n - 1) (1) where. Subject: Modeling of rocket nozzles; effects of nozzle area ratio. The other problem of course is the length of the nozzle. It depends on what you mean by 'most efficient'. Rao's parabolic approximation of a bell nozzle given the. by the bottom dish with an angle up 95° and an expansion ratio of about 1:7. Argon gas enters an adiabatic nozzle steadily at 800 C and 700 kPa with a low velocity, and exits at a pressure of 120 kPa. As air pressure decreases with altitude, the exhaust pressure gradually pushes the flaps closed. 15 synonyms for nozzle: nose, proboscis, beak, snoot, schnoz, schnozzle, snout, nose, hooter, schnoz. In these relations, A* is the throat area, so if there's an expansion ratio of 5, A/A* is equal to 5. 0338 if we follow your definition. This position will provide the greatest reach, but the expansion ratio drops to approximately 4-1. Fluid is blowing thrue a nozzle at the bottom of the plenum and impinges to the plate. There is an optimum expansion ratio for the bell nozzle that maximizes its performance, which still falls short of the aerospike nozzle performance. As the expansion ratio remains above its critical value, the fl ow stays below the critical fl ow. An orifice with diameter D2 = 50 mm is inserted in a pipe with diameter D1 = 114 mm. The appropriate expansion is necessary to avoid the under-expansion or the over-expansion. SCHORR ; Journal of Spacecraft and Rockets Vol. The expansion ratio of the extrusion‐cooked starch increased from 4. Nozzle expansion conditions •Three cases are possible: 1) p e < p a → over-expanded nozzle 2) p e = p a → adapted nozzle 3) p e > p a → under-expanded nozzle •In cases (1) and (3), pressure adjusts to ambient conditions through shock waves outside the nozzle •For a given nozzle geometry, thrust is maximum when nozzle is adapted. A comparison is made between momentum balance and pressure integral methods of calculating the ideal vacuum thrust coefficient, and the results used to examine how corrections should be made for nozzle divergence, skin friction and two-phase flow to obtain the real thrust coefficient of the motor U~Y~j-4. rapidly with pressure decrease. experimentally [8] and numerically [2] investigated. Where A t = Area of Nozzle Throat. Define nozzle. If this is the case, the thrust is given by the above expression for c. Each of these allows the supersonic flow to adapt to the ambient pressure by expanding or contracting, thereby changing the exit ratio so that it is at (or near) optimal exit pressure for the corresponding altitude. The variable expansion ratio geometry did not provide the expected improvements in discharge coefficient and system thrust ratio throughout the flight envelope of typical a supersonic aircraft. The nozzle is gimbaled for thrust vector (direction) control. Body material: stainless steel AISI 316; Inlet connection: carbon steel red epoxy painted (RAL 3000) Nozzles: brass; Optional. 25:1 expansion ratio but actual RS-27 A q exit = 30. The nozzle pressure ratio here is 0. Typical accuracy is 2 to 4% of full scale. 1: UHP P-19 Ultra High Pressure flow characterization results. 4 and a downstream contour area ratio 1:64. methane dual expander aerospike nozzle rocket engine. (2) The effect of a surfactant on the water/concentrate solution; allows the water. In practice, this is more than good enough for the intended purpose of the program. In the present work, the feasibility of an arc-based design method for generation of high-area-ratio nozzle contours has. It has been observed that the use of AWJ technology may lead, in some cases, to better edge stretchability than laser cuts [21]. expansion ratio nozzles have a higher performance than the larger expansion ratio nozzles. Discharge coefficient. The expansion ratio for such a nozzle is given by. Ratio of the cross-sectional area for gas flow at the exit of a nozzle to the cross-sectional area available for gas flow at the throat Explanation of nozzle-expansion ratio. Equations for C -. At high altitude the flaps are closed and sealed such that the multiple engines have a single expansion nozzle 12 feet or more in diameter giving the maximum possible expansion ratio. air/solution ratio up to 20 parts finished foam for every part of foam solution (20:1 ratio). Nozzle exit pressure 3 psia. Rotating the nozzle shaper forward to straight stream (clockwise), will produce lower expansion ratios, but with increased stream reach. with an increase of the pressure ratio; this ratio increases when the value of the chamber pressure Pl increases or when the exit pressure P2 decreases, corre- sponding to high altitude designs. A de Laval nozzle using hot air at a pressure of 1,000 psi (6. For Maximum Stream Reach: Turn nozzle tip with foam tube attached clockwise until it stops in full straight stream position. SERN without cowl and 3h have maximum velocity at throat location and further expansion doesn‟t take place in the diverging section of the nozzle. performance of plug nozzles is then compared to that of linear-walled nozzles for equal pressure ratios, Reynolds numbers, and expansion ratios. A stream of foam solution is sprayed at high speed against an outlet net, drawing into the body the air required and producing foam with an expansion ratio of about 1:20. expansion-ratio: The ratio of the volume of a gas or vapor, such as steam in a thermal engine, after expansion to the volume before expansion began. A relatively high nozzle expansion ratio was chosen for most Warp-9 motors not only to maximize delivered propellant specific impulse but also to help produce thrust levels as high as possible. 0 after 1997. A converging nozzle will choke when Pb is reduced to a critical value P* (found from isentropic relations) Pe = P* is called design pressure ratio. 0 and WRC 107 or 297 is considered for use. Before describing the various forms of annular nozzles, it is useful to mention some key differences in design parameters from the conical or bell nozzles. GAM7 specific heat ratio of exhaust gas at nozzle entrance jet location where exhaust flow has expanded to ambient pressure M9 nozzle exit Mach number based on nozzle expansion ratio Mjet fully expanded jet Mach number Mach Mach number Meas measured NPR nozzle pressure ratio (P8 / Pamb) N1 fan rotor speed, rpm N2 core rotor speed, rpm OH. r ≤ r c the following equation applies; Nozzle Outlet Velocity Equation. And from the Mach number and temperature we can determine. Using a k-factorial statistic test, the performance of the aerospike nozzle will be compared to the control (conventional) nozzle to find if a statistically significant difference in maximum altitude can be achieved with. end devices / Adjustable nozzles Approximate weight: 6 kg Adjustable foam nozzle - mod. TIP, EXPANSION (part #LX-MX-95) Lightweight and easy to use tip attachment. In production. For this reason, we restudied the nozzle design process, hoping that the engine performance can be signiﬁcantly improved only by the nozzle design. Constant chamber pressure throttling of an expansion-deflection nozzle. See also Steam Turbine Nozzles. Nozzle Types Washington State University Hybrid Rocket Team 17 Nozzles with inserts for controlled flow separation Two-position nozzles Dual-bell nozzles Dual expander/ dual throat nozzles Expansion - deflection nozzles Plug nozzles. • When the nozzle is pad reinforced and WRC 107 or 297 is considered for use. To provide the maximum specific impulse at a given altitude, there is a thing called an 'Optimum Contour'. DILUTION RATE, MIXING RATE, OR PROPORTIONING RATE (Correct amount of foam concentrate to be mixed with water): The amount is normally shown on the pail or drum of concentrate. It can be quickly attached and detached to the nozzle via a clip on the nozzle bumper. It can be computed from P0 -- p[1 The and and. Sutton [1]). The following two tabs change content below. Expansion of Steam at 100 o F. High speed images showed that the 15-degree conical. For example, if an air-aspirating nozzle draws in nine units of air for each unit of foam solution discharged, this equates to a 10:1 expansion ratio of finished foam to foam solution. The expansion ratio is the amount of finished expanded foam that will be produced using the correct nozzle. Rudy Garcia is the strategic marketing manager and technical advisor at NP Test. • When the number of full range pressure cycles is greater than 7000 and the nozzle is subject to external loads. department of the air force. The ratio, for a perfect gas, remains constant throughout the expansion process. Finally, a meanline method is proposed to calculate the pressure loss and flow deviation at the nozzle outlet and is compared with CFD results. In actual, as the gas expands, the ratio shifts due to the changes in temperature and the chemical composition. 7 is a one-dimensional and two-dimensional, compressible flow computer program for the analysis of converging-diverging nozzles. The maximum mass flow rate m * is reached at a pressure ratio ε * c. 2b), until eventually the isentropic case, curve f, is reached If the receiver pressure is below the third critical point, an expansion takes place outside the nozzle. Variable two-dimensional convergent-. er_from_p (p_c, p_e, gamma) ¶ Find the nozzle expansion ratio from the chamber and exit pressures. CD nozzles, e. Experiments were conducted in a facility with 1. These area ratios correspond to a pressure ratio (chamber-to-ambient) of 1000 (for the downstream contour) and 148 (for the upstream contour). Expansion ratio: 16:1, 43:1 (with Expansion Nozzle) Cooling method: Film cooled (upper thrust chamber); quartz phenolic chamber ablation (lower thrust chamber) and columbium (niobium) nozzle radiation (Nozzle extension) Chamber pressure: 7. The dual-bell nozzle was designed for ideal isentropic expansion with an upstream contour area ratio of 1:31. The expansion upto throat is taken to be isentropic. 2 km/s) with a 150:1 nozzle. Unlike the temperature, the stagnation pressure during an adiabatic nozzle expansion remains constant only for isentropic flows. The thermodynamic concepts apply to the behavior of real aerospace devices!. The helical port. Recent Developments in Rocket Nozzle Configurations. For optimal performance in vacuum, you want a much larger one. experimentally [8] and numerically [2] investigated. Expansion of Steam at 100 o F. In vacuum, all flaps would be closed for maximum >expansion. #: mode is a string containing, UnderExpanded, OverExpanded, or Separated #: Pc = combustion end pressure (psia) #: Pamb ambient pressure (e. In other words, the hot gases created by burning fuel inside a jet or rocket engine are exhausted through a nozzle to produce thrust. It may correspond to any cross section so long as the inverted ratio with the throat area remains small. In this article series, we'll break the foam family into two primary branches: One is detergent-based, and the other is protein. T1 - Experimental measurements of an expansion deflection nozzle in open wake mode. The diameter ratio can be calculated to. This allow for a simplification of the calculation provided the expansion factor value is available. Medium expansion foams may be used to suppress the vaporization of hazardous chemicals. Rockets depend for their action on Newton's Third Law of Motion that: "For every action there is an equal and opposite reaction. com All trademarks/service marks referenced on this site are properties of their respective owners. In this study, taking the 750N engine as an example, we made a simple and eﬀective modiﬁcation on Rao’s method. It's not adibatic, not isentropic, definitely sonic. In this case the nozzle is said to be. Each device will produce a specific foam quality, such as finished-foam expansion ratio and foam blanket 25 percent drain time. Nozzle Length = Processing Temp (C) = Mould Temp (C) = Solution: Expansion = Ball 1 Ø = 2. Foam solution sprayed from the brass nozzle creates Venturi effect. 15 of the isentropic enthalpy drop. 7L/S; Foam Volume: 105~210cbm/Min; Expansion Ratio: >300; Working Pressure: 0. The nozzle concept consists of four independent, spring-loaded nozzle divergent flaps arranged in a cruciform arrangement. American Institute of Aeronautics and Astronautics 12700 Sunrise Valley Drive, Suite 200 Reston, VA 20191-5807 703. These tools are standard equipment on Engine Companies. 1 Table 1 summarizes. I can envision the corrugated nozzle described above resuming its bell shape, and I can envision a similar folding around the nozzle circumferentially to reduce its length but I'm at a. For Maximum Stream Reach: Turn nozzle tip with foam tube attached clockwise until it stops in full straight stream position. A relatively high nozzle expansion ratio was chosen for most Warp-9 motors not only to maximize delivered propellant specific impulse but also to help produce thrust levels as high as possible. 3 and a throat area of 5 in. Results are reported from a recent study of the effects of Space Shuttle Main Engine expansion ratio modifications, in the cases of both single-stage and two-stage systems. If this rocket were to leave the atmosphere and enter space, how much would the thrust increase or decrease?. High speed images showed that the 15-degree conical. Single Expansion Ramp Nozzle , a linear expansion nozzle, where the gas pressure transfers work only on one side and which could be described as a single-sided aerospike nozzle. The expansion ratio of the rocket nozzle is the simple ratio betwen the area of the throat size and final nozzle area. The expansion ratio, nozzle cross sectional area at exit divided by area at. The nominal thrust, in vacuum, of the engine is 116,000 kgf with a specific impulse of 436 seconds, with a 40:1 nozzle expansion ratio. Each nozzle has a carbon cloth liner that erodes and chars during firing. The nozzle has a throat diameter of 1. The flow of steam through nozzles may be takenas adiabatic expansion. These shocks reduce turbine efficiency and can cause high cycle fatigue (HCF) damage to the downstream rotor blades. O/F ratio: 1. The relation between expansion ratio and pressure ratio can be found from mass conservation and the isentropic relations:. for use in rocket nozzle applications is limited within the public domain [11,12]. With an expansion ratio of 1700:1, 0. Thanks not sure if its 752 m/s or 649 m/s for the answer. This gives us an expansion ratio of 3. NPR = pt8 / p8 = pt8 / p0 Considering the energy equation for the nozzle, the specific total enthalpy ht is equal to the static enthalpy plus the square of the exit velocity divided by two. The objective of this work is to develop guidelines to identify the optimum nozzle geometry that maximizes critical pressure ratio while minimizing pressure drop across the nozzle. • Orifice to upstream pipe diameter ratio of 0. Surface Tension (1) Force minimizing a liquid surface's area. The worksheet output image for this group is given in Figure 1. 0 lbm/lb-mol. sea level=14. #: eps = Nozzle Expansion Area Ratio #: frozen flag, 0=equilibrium, 1=frozen #: frozenAtThroat flag. AU - Sato, Tetsuya. Most large rocket engines use bell-shaped nozzles, which start with a large divergent angle right after the throat, and gradually decrease the angle, ending in a shallow divergent angle at the nozzle exit. URQ-B A pick-up hose at the bottom allows for foam agent to be sucked by an internal Venturi mixer and injected into the water stream with different percentage [0 – 3 – 6]. In really the mass flow rate is a constant and equals m * from point ε * c to an expansion to vacuum ε c =0. an ideal (isentropic) nozzle is obtained directly from an energy balance in the nozzle 2, 5, 6. Expansion of Steam at 100 o F. PY - 2007/10/1. In addition, the computational fluid dynamics program ANSYS Fluent was used to model both a hypothetical. The Expansion Factor \(Y\) is an experimentally derived value that can be used to quantify the difference between and incompressible fluid and a compressible fluid for a nozzle or orifice. The maximum expansion ratio (MER) refers to the biggest expansion ratio of a round section before bursting when hydrobulged at any one time without any preforming; this is an important value that can illustrate the standard of manufacturing techniques of tubular parts with changeable diameters. However, the flow is deflected by a plug, or centerbody, that forces the gases away from the. Recent Developments in Rocket Nozzle Configurations. Where A t = Area of Nozzle Throat. In variable nozzle geometry turbines (VNT), the vanes that form the nozzle are opened to control turbine mass flow and expansion ratio (ER) in order to allow better engine matching and the generation of more turbine power. 7 July 1970. experimentally [8] and numerically [2] investigated. Sizing the nozzle proportions was slightly iterative, in that I had to iteratively determine the perfect-expansion design backpressure such the expansion ratio matched the 40:1 figure reported in Wikipedia. This concept, however, was altered early on to use the uncooled nozzle extension from the 10:1 to the 16:1 expansion plane. Each nozzle has a carbon cloth liner that erodes and chars during firing. The ratio, for a perfect gas, remains constant throughout the expansion process. Computations are conducted for an exit-to-throat area ratio of 1. My question is how is this a perfect expansion ? wouldn't perfect expansion ratio be p/p0=1=po/p?. American Institute of Aeronautics and Astronautics 12700 Sunrise Valley Drive, Suite 200 Reston, VA 20191-5807 703. 9"), this means the sea level Merlin has an expansion ratio of 16:1 while the Merlin Vacuum engine has an expansion ratio of 164:1. By adding the TFT nozzle attachment for foam operations, the expansion ratio is 8 to 1. 395 m 3 of steam at 100 o C (212 o F) (see Figure 6) Figure 6. com All trademarks/service marks referenced on this site are properties of their respective owners. full text of "fortran programs for plug nozzle design" see other formats technical note r-41 fortran programs for plug nozzle design f^fi5^ c-^^ ^ f^^^ prepared by c. Rudy Garcia is the strategic marketing manager and technical advisor at NP Test. One gallon of foam solution will make 1400 gallons of finished foam with the correct nozzle and concentrate. Standard Monitor Range. 𝐺=𝜌 =𝜌 (−2∫ 𝑃 𝜌 𝑃𝑛 𝑃1) (2) where 𝑃1 is the pressure at the valve entrance, 𝑃 is the fluid pressure, 𝑃 is the downstream pressure (pressure at the nozzle exit or nozzle throat), 𝜌. throat x exit pressure, p throat exit} subsonic throughout} shock in nozzle back pressure} oblique shocks in exit jet} reservoir pressure, p0 sonic pressure. A relatively high nozzle expansion ratio was chosen for most Warp-9 motors not only to maximize delivered propellant specific impulse but also to help produce thrust levels as high as possible. Concrete structure. Foam is then produced, with a normal expansion ratio of 1:4, depending upon foam. Specific impulse is the total impulse per unit weight of. department of the air force. Antonyms for Nozzles. The design lever-ages 3-D additive manufacturing to embed a helical fuel port into the thrust chamber of a hybrid rocket burning gaseous oxygen and ABS plastic as propellants. Each device will produce a specific foam quality, such as finished-foam expansion ratio and foam blanket 25 percent drain time. Nozzle Expansion Ratio. Akron Brass offers foam nozzles, handline foam tubes, foam eductors and for firefighting applications. then the ratio is called critical pressure ratio. Nozzles : Rocket nozzles: Expansion of gases from high pressure chamber, efflux velocity, shape of nozzle - Convergent divergent nozzle, choking, variation of parameters in nozzle - Expansion ratio of nozzles, Performance loss in nozzles - Under-expanded and over-expanded nozzles, flow separation - Contour nozzles, adapted nozzles and. Early compressor diffusers used a series of divergent nozzles to convert kinetic energy to pressure via volume expansion. Losses and efficiencies Edit The losses occur in an actual turbine due to disc and bearing friction. Rao's parabolic approximation of a bell nozzle given the. Fixing all other variables (primarily the chamber pressure), there exists only one such ratio that optimizes overall system performance for a given altitude (or ambient pressure). If this is the case, the thrust is given by the above expression for c. The best Nozzle Pressure Ratio (NPR) values are found to be 24. Theoretical astrophysicists have found that pipes with the flow pattern of a De Laval nozzle have analogous phenomena in the interstellar medium. Results show that the extent of influence of the expansion ratio depends on the densimetric Froude number, grain size of the bed material and tailwater conditions. Rocket Nozzles EGR 4347 Analysis and Design of Propulsion Systems Conical Convergent-Divergent Nozzle Separation in Overexpanded Nozzle Summerfield Separation Criterion Pressure Profile at Nozzle Exit Bell-Shaped Nozzle Ae/At=25 Ratio of Actual to Optimum Thrust for Bell-Shaped and Conical Nozzles versus Altitude Bounded and Free-Expansion Nozzles Nozzle Type and Size Comparison Exhaust Flow. This agrees with previous research from NASA that the bene t from the in-crease in area ratio does not overcome the increased viscous losses due to the increase in surface area for small throat areas. Coefficient of nozzle: It is the ratio of actual enthalpy drop to isentropic enthalpy drop. For example, if one gallon of foam solution enters the nozzle and 50 gallons of bubbles exit the nozzle, the expansion ratio is 50/1. Types of nozzles. The focus of the study is on the structure of the fluid and wave phenomena associated with the flow separation. Core stage engines with an operation time of up to 10 minutes feature a medium-range expansion ratio, whereas upper stage engines. Certain results obtained from a thermodynamic analysis of the ejectors have been confirmed in a wide range of geometrical. Gas velocities from 2 to 4. Synonyms for Nozzles in Free Thesaurus. isentropic expansion. If a manufacturer tells you a specific expansion ratio for their nozzle ask them to provide you with the brand of foam, the expansion rate of the foam (low, medium, or high), and the conditions under which the tests results were obtained. Steam Nozzles and Types Nozzle is a duct by flowing through which the velocity of a fluid increases at the expense of pressure drop. then the ratio is called critical pressure ratio. The most common method to account for gas expansion is to determine an Expansion Factor to apply to the incompressible fluid flow equation for a particular device. 65 Mixture Ratio Range 1. Matlab code for simulation of performance for hybrid rocket engines. m generates characteristic net and the contour of nozzle. Let us discuss about the Conical nozzle and bell nozzle. Nozzles and orifices are often used to deliberately reduce pressure, restrict flow or to measure flow rate. expansion ratio can be written as equation (1), in which M stands for Mach numbers of gas, γ is specific heat ratio, A is the area of throat of nozzle and A e is the area of nozzle. Chen et al. Initially, during launch and low subsonic operation, all four divergent flaps would fixed in a closed position thus providing a low nozzle expansion ratio. A diffuser is a device which slows down fluid. I must caution you that the nozzle type alone will not determine the final application rate. 068 MPa the mass flow rate is 0. It would switch propellant to MMH plus hexamethyldisilazone (HMZ) and N 2 O 4 on a 1. The variable expansion ratio geometry did not provide the expected improvements in discharge coefficient and system thrust ratio throughout the flight envelope of typical a supersonic aircraft. EXPANSION RATE: Volume of finished foam divided by the volume of foam solution used to create the finished foam; i. This will be found at a specific cross-sectional area of the nozzle exit, Ae, of a given rocket, which may be related to the throat cross-sectional area as the nozzle area expansion ratio. At high altitude the flaps are closed and sealed such that the multiple engines have a single expansion nozzle 12 feet or more in diameter giving the maximum possible expansion ratio. Questions? Can this nozzle ever produce a supersonic flow in the. Thrust is calculated according to the relationship: FmvexitPexitPambAexit (1). 3 cm cylindrical plenum assembly shown photographed in Fig. nozzle expansion ratio (ratio of the nozzle exit area A e to the nozzle throat area A t) in the range A e/A t#1y2. 3 baseline (no step) case is shown in Fig. It is usually comparable to or a few percent lower than that for a fixed geometry turbine. If, instead of the default case overflow capacity of 28. The focus of the study is on the structure of the fluid and wave phenomena associated with the flow separation. 3 is also presented in the hover case. Design considerations for an optimum nozzle shape with a specific expansion ratio is that the gas flow at the nozzle exit must be uniform and axial for obtaining maximum momentum vector with minimum separation and negligible losses. 2) Subsonic and Supersonic Nozzles 3) Rocket C-D Nozzles 4) Generation of thrust 5) Over Expanded and Under Expanded Nozzles I hope you take away some new concepts in fluid mechanics after this video. With this kind of expansion ratio for this engine, the nozzle flow is not over expanded. (Proportioner) and the Low Expansion Foam Nozzle. 09063 as per their definition and it would be 1/0. 000: BL1 = Ball 2 Ø= BL2 = L tool = Signup to the Mastip. Marshall A thrust augmented nozzle for hybrid rocket systems is investigated. 10 Nominal foam production is the volume of foam produced per time unit, i. The large bell- or cone-shaped nozzle extension beyond the throat gives the rocket engine its characteristic shape. The variable expansion ratio geometry did not provide the expected improvements in discharge coefficient and system thrust ratio throughout the flight envelope of typical a supersonic aircraft. The ratio of the volume of foam generated (finished foam) to the foam concentrate used in that is called expansion ratio of the foam. Although there is expansion across the turbine nozzle, therefore some cooling of the gasses, the temperature at the tips of the turbine rotor can approach exhaust gas temperatures. Insulating expansion foam ("spray foam") is measured by how much the liquid form of it expands once it's dispensed out of its container (hence the terms "high expansion" and "low expansion" foam). The most common method to account for gas expansion is to determine an Expansion Factor to apply to the incompressible fluid flow equation for a particular device. The performance of rocket engines is highly dependent on the aerodynamic design of the expansion nozzle, the main design parameters being the contour shape and the area ratio. Antonyms for Nozzles. Discharge coefficient. 3 - 4 Reversible adiabatic (isentropic) expansion producing power output. The following two tabs change content below. It is denoted by K. have an area of 0. p c / p 1 = ( 2 / (n + 1) ) n / (n - 1) (1) where. And from the Mach number and temperature we can determine. These area ratios correspond to a pressure ratio (chamber-to-ambient) of 1000 (for the downstream contour) and 148 (for the upstream contour). The flow separates by the action of a lambda shock, followed by a succession of expansion and compression waves. 15 synonyms for nozzle: nose, proboscis, beak, snoot, schnoz, schnozzle, snout, nose, hooter, schnoz. A non-simple region is characterized by Mach wave. HALLENBECK B. Symbol for neptunium. 72 expansion ratio, while a 7. NASA CEA online was used to calculate the ratio of specific heats (γ) at the throat (γ*t) and at the nozzle exit (γe), the temperature in the combustion chamber (Tc), the molar mass of the products at the exit (M), and the pressure at the exit with the expansion ratio of 16 (Pe*), across pressures from 8. Nozzle efficiency: It is the ratio of useful heat drop to the isentropic heat drop. Core stage engines with an operation time of up to 10 minutes feature a medium-range expansion ratio, whereas upper stage engines. 0 lbm/lb-mol. nozzle-expansion ratio; nozzle-mix gas. Corundum, sintered. 9 MPa or 68 atm), temperature of 1470 K, would have a pressure of 540 psi (3. The speed increase of a rocket nozzle is mostly determined by its area expansion ratio—the ratio of the area of the throat to the area at the exit, but detailed properties of the gas are also important. A nozzle consisting of a circular inlet orice and a short chamber with an exit lip can produce a naturally oscillating jet ow if the expansion ratio from inlet to chamber (D/d1) is larger than ve. Insulating expansion foam ("spray foam") is measured by how much the liquid form of it expands once it's dispensed out of its container (hence the terms "high expansion" and "low expansion" foam). This trend is plotted in Figure 3. Baseline operation was at a mixture ratio of 5. Ratio of the cross-sectional area for gas flow at the exit of a nozzle to the cross-sectional area available for gas flow at the throat. Nozzle expansion conditions •Three cases are possible: 1) p e < p a → over-expanded nozzle 2) p e = p a → adapted nozzle 3) p e > p a → under-expanded nozzle •In cases (1) and (3), pressure adjusts to ambient conditions through shock waves outside the nozzle •For a given nozzle geometry, thrust is maximum when nozzle is adapted. 3 times the nozzle exit diameter in the base region. 3mm, representations of A/B power setting on ground labeled as type A; b) the nozzle expansion ratio was 1. The expansion state is characterized by the nozzle pressure ratio n, i. The expansion ratio is the amount of finished expanded foam that will be produced using the correct nozzle. Foam is then produced, with a normal expansion ratio of 1:4, depending upon foam. Velocity Co-efficient is square root of the nozzle efficiency when the inlet velocity is assumed to be negligible. They used the semi-algebraic Method of Characteristics (of supersonic flow) to devise such a nozzle, for whatever nozzle expansion ratio ϵ was required. You can change the shape of the diverging section by clicking the area shaded with '+' signs close to the line representing the diverging section. The performance of rocket engines is highly dependent on the aerodynamic design of the expansion nozzle, the main design parameters being the contour shape and the area ratio. Fixed or automatic fog nozzles, air aspirating attachments and high-expansion foam generators introduce different volumes of air into foam solution to create various finished-foam blanket qualities. Chapter Six/ / Isentropic Flow in Converging Nozzles ----- 4-6 ch. Nozzle exit pressure 3 psia. The thrust chamber provided a combustion chamber for burning propellants and an expansion nozzle for expelling gasses produced by the burned propellants at high velocity to produce thrust. 5) and combustion pressure in the chamber (2. 0 Nozzle Development The larger RSRMV required a modified nozzle design RSRM nozzle utilized a 7. Systematic computations were also performed to investigate the effects of nozzle length and nozzle expansion ratio. In all cases, the ratio of inlet total pressure to exit static pressure, which is called nozzle pressure ratio, are set to be 7. The calculation results show that increasing the heat capacity ratio can produce an expansion contour of smaller expansion angle and exit area ratio. The variable expansion ratio geometry did not provide the expected improvements in discharge coefficient and system thrust ratio throughout the flight envelope of typical a supersonic aircraft. Expansion Factor. As the rocket motor with fixed expansion ratio nozzle ascends through the atmosphere the ambient pressure drops exponentially. Cellulose acetate (CA) Cellulose acetate butyrate (CAB) Cellulose nitrate (CN) Chlorinated polyvinylchloride (CPVC) Clay tile structure. A sea level merlin has a nozzle that's 0. performance of plug nozzles is then compared to that of linear-walled nozzles for equal pressure ratios, Reynolds numbers, and expansion ratios. 7 corresponding to an ideal design pressure ratio of 374. The ratio between the jet exit and ambient static pressures is called the under-expansion ratio. A nozzle extension is an extension of the nozzle of a reaction/rocket engine. NPR = pt8 / p8 = pt8 / p0 Considering the energy equation for the nozzle, the specific total enthalpy ht is equal to the static enthalpy plus the square of the exit velocity divided by two. The lightweight design, which evolved from Pratt's conventional balanced-beam nozzle, allows independent control of nozzle expansion ratio and vectoring capability up to 20 degrees in any direction. The actual length of the nozzle is up to the creator, but the nozzle I created ended with a total length of 2. 5 on command for optimized propellant utilization during the mission. Find garden hose nozzles & wands at Lowe's today. Nozzle Critical Pressure Ratio: Nozzle Outlet Area Equation. The relation between expansion ratio and pressure ratio can be found from mass conservation and the isentropic relations:. moen, capt, usaf. The nozzle pressure ratio here is 0. It has higher Expansion Ratio – as addition of divergent portion produces steam at higher velocities. For example, if one gallon of foam solution enters the nozzle and 50 gallons of bubbles exit the nozzle, the expansion ratio is 50/1. The ratio, for a perfect gas, remains constant throughout the expansion process. Baseline operation was at a mixture ratio of 5. Theoretical calculations of specific impulse to determine the separate effects of increasing the combustion-chamber pressure and the nozzle expansion ratio on the performance of the propellants, hydrogen-fluorine, hydrogen-oxygen, ammonia-fluorine and AN-F-58 fuel - white fuming nitric acid (95 percent). The abrupt expansion was formed, by inserting, into the main tube, a perspex nozzle block with the nozzle contours shaped to a standard ASME long-radius profile. This is an easy way to acquire a thicker finished foam blanket. The first is an attachment for the typical fog nozzle. To provide the maximum specific impulse at a given altitude, there is a thing called an 'Optimum Contour'. 4 and then decreased gradually to 8.