Characterization of Cryogenic Injection at Supercritical Pressure

Understanding the Complex environment of the rocket chamber involves good knowledge of the injection phenomena. Understanding the injection phenomena allows the rocket designer to employ time and cost saving modeling tools to design a higher performance rocket engine. The rocket engine performance is highly dependent on the injection processes within the chamber. This project looked at injection processes in the supercritical regime of the injected fluid, cryogenic nitrogen, in order to better understand realistic conditions in the rocket engines of today. The investigation considered test conditions from 4.0 to 6.0 MPa at two different injection velocities and temperatures. Experimental data taken by Raman imaging and Shadowgraphy were compared to computational models for these various test conditions. The test data allows comparisons of density, length scales and jet spreading angles. The results validate the computational models fairly well and agree with classical theory.This agreement allows further use of the models to predict injection behavior under these operating conditions. Also, further comparisons were made between the various test cases using the computational models to consider the effects of pressure, velocity and temperature variations on the cryogenic jet.