Rocket Performance Prediction Technique

Abstract

A simple, semi-empirical performance correlation^prediction technique applicable to gaseous and liquid propellant rocket engines is presented. Correlations were attained by "adjusting" the computation of the gaseous mixing of an un re active, coaxial jet using a correlation factor, F, which resulted in prediction of the experimental combustion efficiency for each firing. The technique was successfully applied to Rocket dyne, Aerojet, TRW, and Bell Aerospace gaseous H 2 /0 2 rocket engines utilizing coaxial, triplet, trislot, premix, and reverse flow injector elements, and to Bell's 6000 Ib-thrust orbital maneuvering and 600 Ib-thrust reaction control engines, which utilize triplet and unlike doublet injector elements, respectively, and liquid monomethylhydrazine and nitric oxide propellants. Test data from over 100 firings, representing a wide range of engine sizes and flow conditions, were compressed when the correlation factor, F, times the chamber length, L, divided by the "effective" radius, /?/, was plotted vs the ratio of the injection velocity of the fuel divided by the injection velocity of oxidizer. The resulting correlations are useful for comparing the effectiveness of different injectors at the same velocity ratios (which are proportional to the mass flux ratios), for predicting optimum operating conditions for a given injector geometry, and for assessing the consistency of test data. Before liquid rocket performance predictions can be made with confidence, additional liquid rocket data, covering a wider range of conditions, must be correlated. LA» P EL F f G MW m PC Pr T R r Sc T