Performance Evaluation of Second-Throat Diffuser for High-Altitude-Test Facility
| Autor: | D. Raja Manohar, R. Manikanda Kumaran, Thirumalachari Sundararajan |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Backflow
Stagnation temperature Materials science Vacuum Nozzle Steady and transient Aerospace Engineering Experimental data Static pressure Numerical simulation Rocket motor Physics::Fluid Dynamics Shock-cell Exit diameter Vacuum environment High altitude Axial variations Reverse flow Test facilities Choked flow Diffuser systems Nozzles Sensitive parameter business.industry Mechanical Engineering Stagnation pressures Nozzle exits Structural engineering Mechanics Computer simulation Inlet flow Test chambers Chamber pressure Rocket engines Fuel Technology Space and Planetary Science Performance evaluation Oblique shock business Stagnation pressure |
| Zdroj: | Journal of Propulsion and Power. 26:248-258 |
| ISSN: | 1533-3876 0748-4658 |
| DOI: | 10.2514/1.43298 |
| Popis: | 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. Copyright � 2009 by the American Institute of Aeronautics and Astronautics, Inc. |
| Databáze: | OpenAIRE |
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