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Journal ArticleDOI

CFD Analysis for Simulated Altitude Testing of Rocket Motors

01 Jun 2002-Canadian Aeronautics and Space Journal (NRC Research Press Ottawa, Canada)-Vol. 48, Iss: 2, pp 153-162
TL;DR: In this article, the authors deal with the high-altitude simulation and testing of upper stage rocket motors with large nozzle area ratios, using second-throat exhaust diffusers (STED).
Abstract: This paper deals with the high-altitude simulation and testing of upper stage rocket motors with large-nozzle area ratios, using second-throat exhaust diffusers (STED). To evaluate the performance ...
Citations
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Journal ArticleDOI
TL;DR: In this article, the starting transient and plume blowback at diffuser breakdown of a straight cylindrical supersonic exhaust diffuser with no externally supplied secondary flow are numerically investigated.

36 citations

Journal ArticleDOI
TL;DR: In this paper, the design and operational parameters of rocket exhaust diffusers equipped to simulate high-altitude rocket performance on the ground were investigated and characterized using a comprehensive approach (theoretical, numerical, and experimental).
Abstract: The design and operational parameters of rocket exhaust diffusers equipped to simulate high-altitude rocket performance on the ground were investigated and characterized using a comprehensive approach (theoretical, numerical, and experimental). The physical model of concern includes a rocket motor, a vacuum chamber, and a diffuser, which have axisymmetric configurations. Further, the operational characteristics of a rocket exhaust diffuserwereanalyzed froma flowdevelopmentpointof view.Emphasiswasplacedondetailed flowstructure inthe diffuser, to observe the pressure oscillation in both the vacuum chamber and diffuser, which determines the minimum rocket-motor pressure required to start the diffuser. Numerical simulations were compared with experimental data on startup and in operational conditions to understand the effects of major design parameters, including the area ratio of diffuser to rocket-motor nozzle throat, the rocket-motor pressure, and the vacuumchamber size. Nomenclature Ad = inner cross-sectional area of diffuser Ade = exit cross-sectional area of diffuser Ae = exit cross-sectional area of rocket nozzle At = throat cross-sectional area of rocket nozzle

27 citations


Cites background from "CFD Analysis for Simulated Altitude..."

  • ...Studies on testing methods, design methods, and the internal flow of diffuser systems simulating high-altitude conditions have been performed in research institutes, industries, and academic laboratories since the mid-1950s [5–12]....

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Journal ArticleDOI
TL;DR: In this paper, the effects of essential performance parameters on the starting transient of a straight cylindrical supersonic exhaust diffuser (SED) are numerically investigated in terms of SED length and pre-evacuation configuration.

24 citations

Journal ArticleDOI
TL;DR: In this paper, the performance of a second-throat ejector diffuser system employed in high-altitude testing of large-area-ratio rocket motors is considered under various steady and transient operating conditions.
Abstract: The performance of a second-throat ejector―diffuser system employed in high-altitude testing of large-area-ratio rocket motors is considered under various steady and transient operating conditions. When the diffuser attains started condition, supersonic flow fills the entire inlet section and a series of oblique shock cells occurring in the diffuser duct seal the vacuum environment of the test chamber against backflow. The most sensitive parameter that influences the stagnation pressure needed for diffuser starting is the second-throat diameter. Between the throat and exit diameters of the nozzle, there exists a second-throat diameter value that corresponds to the lowest stagnation pressure for starting. When large radial/axial gaps exist between the nozzle exit and diffuser duct, significant reverse flow occurs for the unstarted cases, which spoils the vacuum in the test chamber. However, the starting stagnation- pressure value remains unaffected by the axial/radial gap. Numerical simulations establish that it is possible to arrive at an optimum diffuser geometry that facilitates early functioning of the high-altitude-test facility during motor ignition phase. The predicted axial variations of static pressure and temperature along the diffuser for the testing of a cryogenic upper-stage motor agree well with available experimental data.

24 citations


Additional excerpts

  • ...Numerical investigations [19–24] are quite helpful in analyzing the performance of different ejector– diffuser subsystems under design and offdesign modes of operation and also for understanding the flow features, including the structure of shock cells....

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Journal ArticleDOI
TL;DR: In this article, a second throat ejector using nitrogen as the primary fluid is considered for the creation of a low vacuum in a high-altitude testing facility for large-area-ratio rocket motors.
Abstract: DOI: 10.2514/1.39219 In the present work, a second throat ejector using nitrogen as the primary fluid is considered for the creation of a low vacuum in a high-altitude testing facility for large-area-ratio rocket motors. Detailed numerical investigations have been carried out to evaluate the performance of the ejector for various operational conditions and geometric parametersduring thenonpumpingandpumpingmodesof operation.Inthenonpumpingmode,the lowestvacuum chamberpressureisattainedwhentheprimaryjetjustexpandsuptothemixerthroatandtheresultingsingleshock cellsealsthethroatagainstanybackflow.Thestudyillustrateshoweachgeometricandoperationalparameterofthe ejector can be optimized to meet the test requirements in a high-altitude testing facility byensuring that the primary jet completely expands without a strong impact on the duct wall. When the rocket motor is fully started, due to the self-pumping action, the required vacuum is almost maintained by the exhaust flow itself and the external nitrogen ejector plays only a supplementary role. Numerical predictions for both nonpumping and pumping modes of operation have been validated with experimental data obtained from a scaled-down model of a high-altitude testing facility.

23 citations


Cites background from "CFD Analysis for Simulated Altitude..."

  • ...Computational fluid dynamics (CFD) simulations [15–19] show that the STED can be started even with a normal shock forming ahead of the second throat contraction....

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References
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Journal ArticleDOI
TL;DR: In this article, a straight cylindrical supersonic exhaust diffusers (SED) using cold nitrogen and hot rocket exhaust gases as driving fluids were used to evaluate the effects of the ratios of the SED area to rocket nozzle throat area (Ad/At), SED areas to rocket exhaust manifold exit area, SED length to its diameter (L/D), and specific heat ratio of the driving gases (k) on the minimum starting pressure ratio, (Po/Pa)st, of SED.

64 citations

Journal ArticleDOI
TL;DR: Theoretical methods for estimating the required starting pressure ratio and minimum base pressure ratio of axisymmetric ejector-diffuser systems used in rocket altitude simulation are presented in this paper.
Abstract: Theoretical methods are presented for estimating the required starting-pressure ratio and minimum base pressure ratio of axisymmetric ejector-diffuser systems used in rocket altitude simulation. The starting-pressure ratio is determined by applying over-all conservation relations; the theory also predicts the limiting second-throat contraction ratio, which can exceed the normal-shock-starting contraction limit for wind tunnels. Experimental starting data from 79 axisymmetric ejector systems agree with this theory within approximately 10%. The theory for the minimum base pressure ratio for zero secondary flow was developed by modifying Korst's two-dimensional theory to be applicable to axisymmetric systems. The modification consists of a new method for computing the peak recompression static pressure. Measured base pressures of 34 ejector configurations agreed with the latter within 6%.

46 citations


"CFD Analysis for Simulated Altitude..." refers background in this paper

  • ...To evaluate the performance of such motors in ground-testing installations, the low-pressure environment of the upper atmosphere has to be simulated (Gothert, 1962; Roschke et al., 1962; German et al., 1966; Annamali et al., 1998; Panesci and German, 1963; Bauer and German, 1961; Wang and Chen, 1996; and Chen et al., 1994)....

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  • ...Also, for a quick evaluation of the ejection characteristics of the diffuser, a small cell, which corresponds to the corner region of a backward-facing step, may be used instead of a large vacuum chamber (Gothert, 1962; Roschke et al., 1962; German et al., 1966; Wang and Chen, 1996; and Chen et al., 1994)....

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  • ...A STED system is said to be operating in “started” condition if the motor exhaust occupies the entire cross sections of the rocket nozzle as well as the diffuser (German et al., 1966)....

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Journal ArticleDOI
TL;DR: In this paper, a second-order high-resolution scheme for solving the new Lagrangian Euler equations is employed to accurately resolve the complicated shock patterns and associated slip lines and their interactions.
Abstract: A computational analysis of the two-dimensional supersonic inviscid flowfield in a second-throat ejector-diffuser (STED) system is presented. A second-order high-resolution scheme for solving the new Lagrangian Euler equations is employed to accurately resolve the complicated shock patterns and associated slip lines and their interactions. A parametric study covering a variety of Xst and Ost is implemented to investigate their effects on the flow structure in STED as well as its performance. Results suggest that the averaged Mach number along the entrance plane of the second throat is a suitable criterion for the justification of the performance of STED. With this criterion, an optimal design insuring the largest pressure recovery can be achieved.

41 citations


Additional excerpts

  • ...0 (Wang and Chen, 1996; Chen et al., 1994)....

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Journal ArticleDOI
TL;DR: Forster, H. P. and Tuthill, W. C. as discussed by the authors, discussed the effects of acceleration on nucleate pool boiling and proposed a method for heat rejection from space power plants.
Abstract: drogen," NASA News Release 61-12, and "Space zero g fuel studies to aid centaur, Rover and Saturn propulsion programs," Western Aviation, Missiles and Space 41, 12-13 (February 1961). 58 Adelberg, M. and Forster, H. K., Discussion of Ref. 16, J. Heat Transfer 83, 251-253 (1961). 59 Forster, H. K., Private communication (1960). 60 Allingham, W. D. and McEntire, J. A., "Determination of boiling film coefficient for a heated horizontal tube in a water-saturated wick material," Am. Soc. Mech. Engrs., J. Heat Transfer 83, Series C, 71-76 (February 1961). 61 Ginwala, K. (ed.), "Engineering study of vapor cycle cooling equipment for zero gravity environment," Wright Air Dev. Div. TR 60-776 (January 1961). 62 Costello, C. P. and Tuthill, W. E., "Effects of acceleration on nucleate pool boiling," Am. Inst. Chem. Engrs., Chemical Engineering Progress Symposium Series 57, no. 32, p. 189 (1961). 63 Costello, C. P. and Adams, J. M,, "Burnout heat fluxes in pool boiling at high accelerations," 1961 International Heat Transfer Conference (American Society of Mechanical Engineers, New York, 1961), Part I I , pp. 255261. 64 Silvern, D. H., Collins, J. L., Hays, L., and Haire, A., "Design of a surface radiator-condenser for use in a space environment," ElectroOptical Systems Rept. 310-DR (October 1959). 65 Koestel, A., "Hydrodynamic problem areas in zero gravity," TapcoTRW Tech. Memo 1488 (November 1959). 66 Payne, J., Private communication (1960). 67 Reitz, J. G., "Zero gravity mercury condensing research," Aerospace Eng. 19, 18-23 (September 1960). 68 Cummings, R. L., Grevstad, P. E., and Reitz, J. G., "Orbital force field boiling and condensing experiment," Weightlessness-Physical Phenomena and Biological Effects, edited by E. T. Benedikt (Plenum Press, New York, 1961), pp. 121-132. 69 Jaenke, C. T., Koestel, A., and Reitz, J. G., "Snap II power conversion system topical report no. 13—OFFBACE testing," ThompsonRamo Wooldridge Rept. ER-4670 (November 1961). 70 Lieblein, S. (ed.), "Government-industry conference on mercury condensing, April 18, 1961, Pasadena, California," NASA TN D-1188 (February 1962). 71 Grevstad, P. E., TAPCO Group, New Devices Laboratories, Thompson-Ramo Wooldridge, Private communication (1960). 72 Weatherston, R. C. and Smith, W. E., "A method for heat rejection from space power plants," ARS J. 30, 268 (1960). 73 "Rocketdyne develops space heat radiator," Aviation Week 73, 65 (October 10, 1960). 74 Hays, L., Collins, J., and Neustein, J., "Investigation of spray type condensers with mercury and water," Proceedings of the 1961 Heat Transfer and Fluid Mechanics Institute (Stanford University Press, Stanford, Calif., 1961), pp. 114-129. 75 Kittinger, J. W., "The long, lonely leap," Natl. Geographic Mag. 118, 854(1960).

32 citations


"CFD Analysis for Simulated Altitude..." refers background in this paper

  • ...To evaluate the performance of such motors in ground-testing installations, the low-pressure environment of the upper atmosphere has to be simulated (Gothert, 1962; Roschke et al., 1962; German et al., 1966; Annamali et al., 1998; Panesci and German, 1963; Bauer and German, 1961; Wang and Chen, 1996; and Chen et al., 1994)....

    [...]

  • ...Also, for a quick evaluation of the ejection characteristics of the diffuser, a small cell, which corresponds to the corner region of a backward-facing step, may be used instead of a large vacuum chamber (Gothert, 1962; Roschke et al., 1962; German et al., 1966; Wang and Chen, 1996; and Chen et al., 1994)....

    [...]

Journal ArticleDOI
TL;DR: It is suggested that a STED can be started with a normal shock forming ahead of the second-throat contraction because the high speed flow in the region close to the wall of the diffuser serves to release the mass blocked by the normal shock, leading to a decrease in chamber pressure as well as the start of the system.
Abstract: The start condition of a second-throat ejector-diffuser (STED) system has been studied by solving the axisymmetric Navier-Stokes equations with a high order conservative supra-characteristics method (CSCM). According to the conventional concept, when a STED is started, the flow passing through the second-throat contraction should be supersonic so that the normal shock swallowing condition applying for a supersonic windtunnel holds. The present numerical results, however, suggest that a STED can be started with a normal shock forming ahead of the second-throat contraction because the high speed flow in the region close to the wall of the diffuser serves to release the mass blocked by the normal shock, leading to a decrease in chamber pressure as well as the start of the system. This not only contradicts the conventional concept of the start of a STED, but also provides an explanation for the experimental discrepancy between the start conditions of a STED and a supersonic windtunnel.

19 citations


"CFD Analysis for Simulated Altitude..." refers background in this paper

  • ...0 (Wang and Chen, 1996; Chen et al., 1994)....

    [...]

  • ...To evaluate the performance of such motors in ground-testing installations, the low-pressure environment of the upper atmosphere has to be simulated (Gothert, 1962; Roschke et al., 1962; German et al., 1966; Annamali et al., 1998; Panesci and German, 1963; Bauer and German, 1961; Wang and Chen, 1996; and Chen et al., 1994)....

    [...]

  • ...Also, for a quick evaluation of the ejection characteristics of the diffuser, a small cell, which corresponds to the corner region of a backward-facing step, may be used instead of a large vacuum chamber (Gothert, 1962; Roschke et al., 1962; German et al., 1966; Wang and Chen, 1996; and Chen et al., 1994)....

    [...]

  • ...configuration (Panesci and German, 1963; Bauer and German, 1961; Wang and Chen, 1996; and Chen et al., 1994)....

    [...]