Simplified Procedures for Correlation of Experimentally Measured and Predicted Thrust Chamber Performance

ABSTRACTThrust chamber performance should be evaluated in terms of ananalytical model incorporating all the loss processes that occur in a realrocket motor. The Performance Standardization Working Group of JANNAFhas identified the important loss processes in the real thrust chamber, andhas developed a methodology and a recommended procedure for predictingreal thrust chamber vacuum specific impulse.Simplified equations, based on the JANNAF reference procedure forcalculating vacuum specific impulse, are developed to relate the deliveredperformance (both vacuum specific impulse and characteristic velocity) tothe ideal performance as degraded by the losses corresponding to a specifiedlist of loss processes. These simplified equations enable the various per-formance loss components, and the corresponding efficiencies, to be quanti-fied separately (except that interaction effects are necessarily arbitrarilyassigned in the process).The loss and efficiency expressions presented can be used to evaluateexperimentally measured thrust chamber performance, to direct develop-i merit effort into the areas most likely to yield improvements performance,inand as a basis to predict performance of related thrust chamberconfigurations.