Flow separation and side-load behavior of truncated ideal rocket nozzles

Abstract

Flow separation and side-loads in truncated ideal rocket nozzles were analyzed by means of analytical and ex- perimental work. The free shock separation (FSS) behavior, where the overexpanded exhaust flow separates from the nozzle wall without any further re-attachment, is discussed. The associated side-load phenomena due to pressure pulsation in the incipient separation zone and in the fully separated flow regime with a developed recirculation zone are also discussed. Both, separation and side-load characteristics measured in different sub- scale cold gas tests are analyzed. An analytical side-load model for predicting aerodynamic side-loads caused by pressure pulsation is presented using statistical methods. The comparison of predicted aerodynamic side- loads with experimental data shows a fairly good agreement.