Low frequency combustion instability, known as chugging, is consistently experienced during shutdown in the fuel and oxidizer preburners of the Space Shuttle Main Engines. Such problems only occur during the helium purge of the residual oxidizer from the pre-burner manifolds during the shutdown sequence. Possible causes and triggering mechanisms are analyzed and details of modeling the fuel pre-burner chug are presented in this report. A linearized, one dimensional, lumped parameter chugging model capable of predicting the chug occurrence is discussed and the predicted results are presented and compared to experimental work performed by NASA. In addition to predicting the actual instability, a parametric study of the various parameters such as chamber pressure, fuel and oxidizer temperatures and the effective bulk modules of the liquid oxidizer are considered in analyzing the fuel preburner chug. Particular attention has been given to such parameters as fuel and oxidizer temperatures since these vary with engine thrust at shutdown. Results of these predictions and the parametric studies are presented in this paper. A Fortran computer program is utilized to generate the stability boundary for each sensitivity study and the region for stable operation is identified.
Combustion stability analysis of preburners in liquid propellant rocket engines during shutdown
Verbrennungsstabilitaet von Vorbrennern in Fluessigtreibstoffraketenantrieben waehrend der Stillegung
AIAA-Papers ; Jul ; 1-8
1987
8 Seiten, 9 Bilder, 5 Quellen
Aufsatz (Konferenz)
Englisch
Liquid-Propellant Rocket Engines
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