Measurements of Energy Losses Associated with Interactions Between Acoustic Waves and Non-Uniform Steady Flow

摘要

An experimental program has been conducted to study interactions between acoustics waves and two types of non-uniform average flow occurring in solid propellant rockets. Measurements in a resonance tube confirmed the existence of an energy loss associated with interactions between a longitudinal acoustic field and an average flow entering through a lateral boundary. The measured loss was approximately five times as large as that predicted by a simple one-dimensional analysis. However, due to the large experimental uncertainty associated with these results, the confidence level of their quantitative validity is low. In the second part of the program, a small supersonic wind tunnel has been operated open cycle with the test section, upstream of a choked nozzle, used as an impedance tube to measure the admittance function for the nozzle. Limited results for simulated submerged nozzles suggest that secondary flow has little influence on the admittance function for the aft end of the chamber. (Author)