Acoustic Simulation of Hot Jets Issuing from a Rectangular Hypersonic Nozzle

摘要

Acoustic simulation of hot jets issuing from a rectangular hypersonic nozzle was carried out The aim of this study is, even though qualitative to some extent, to establish a method capable of predicting the acoustic characteristics of the high-temperature and high-velocity jets issuing from the realistic hypersonic nozzle having a complicated geometry. Two kinds of test nozzles, 2.4% scaled model with afterburner for hot jet experiments and 1.0% scaled model for cold-air/helium mixture jet experiments, were manufactured and tested. By using a high-enthalpy wind-tunnel plant, acoustic characteristics of the hot jets issuing from the rectangular hypersonic nozzle for several representative but realistic high-temperature and high-velocity jet conditions were obtained. At the same time, by using a small anechoic chamber, the acoustic characteristics of the hot jets were duplicated using cold-air/helium mixture jets having the same velocities. Although we have to pay attention to some noted exceptions, the directivity patterns and the spectral shapes for cold-air/helium mixture jets reasonably agree with those for the hot-air jet and the hot jt with afterburner under lean-burn condition with the error of 2 dB or less.