Experimental and Numerical Studies of Secondary Injection in Nozzle Divergence for Thrust Augmentation

Thrust augmentation in rocket engines using secondary injection in the diverging part of a nozzle is an innovative extension of after burners. This technique finds application in single stage to orbit propulsion devices, where the nozzle has to work at varying ambient pressures. Experimental and numerical studies have been conducted with varying cross flow and injection conditions to analyse the performance augmentation in a 2D nozzle. Schlieren images and wall pressure data are obtained from the experiment. Simulations are conducted using a HLLC scheme based finite volume solver. A detailed description of flow physics resulting due to the introduction of sonic angled jet into expanding supersonic flow is presented. It is found that the injection angle, pressure and main flow pressure have notable influence in the performance of the nozzle.