CHARACTERISTICS OF NEAR-FIELD ROCKET NOISE OF A SINGLE-CHAMBER TWO-STAGE ROCKET ENGINE

Near-field rocket noise impacts on launching system and rocket itself directly with harmful effect. It has some characteristics different from those of well-predicted far-field rocket noise. Single-chamber two-stage rocket engines were used to study near-field rocket noise in stationary experiment. These have one peak and two steady stages in the chamber pressure, which are helpful to demonstrate the characteristics of near-field rocket noise clearly. Experiment shows magnitude of noise pressure has close relation with chamber pressure, but normalized peak frequency changes little along with chamber pressure. Power spectrum and joint time-frequency analysis are used in process the noise data. Normalized peak frequencies are approximately 0.04 (fDe/Ue) which is two times higher than that of far-field rocket noise. The results are useful to assess impact effect on launching system and obtain prediction method for near-field rocket noise.