单喷管火箭自由喷流噪声数值模拟

利用非定常燃气流场数值模拟方法，研究超声速喷流核心区及其外围亚声速区燃气流动态分布和流动特性，在此基础上利用欧拉方程条件的伽辽金有限元方法以及FWH方法，实现并完成喷流噪声传播特性、辐射特性数值模拟。喷流噪声数值模拟结果显示：燃气流推进初期，强喷流噪声区域紧随燃气流前锋；燃气流场相对稳定后，强喷流噪声区域主要位于燃气流等能区末稍，一些小尺度试验的燃气流激波系附近也存在较强喷流噪声。这些强喷流噪声主要由燃气流前锋带动的大涡动态卷吸、燃气流强湍流脉动以及激波扰动引起。受数值模拟网格分辨率影响，当前仅能保持中低频段声压级数值模拟结果与实测结果总体接近。

Numerical Simulation on Free Jet Noise of Single Nozzle Rocket

The dynamic flow and distribution characteristics of the gas flow in the core region of a supersonic jet and its adjacent peripheral subsonic region are studied by using the numerical simulation method of an unsteady gas flow field. On these bases, the numerical simulation of the jet noise propagation and emission characteristics is completed by using the FWH method and the Galerkin finite element method in solving the Euler equation. The numerical simulation results show that the propagation area of the strong jet noise follows the free advancing jet flow front. After the free jet flow field is relatively stable, the propagation area of the strong jet noise is mainly at the end of the equal-energy zone of free jet flow, and some small scale tests also have strong jet noise near the shock wave system of the free jet flow. The strong jet noise is mainly caused by the large eddy dynamic suction driven by the free advancing jet flow front, the strong turbulence pulsation of the gas flow and the shock disturbance. Due to the influence of the grid resolution of numerical simulation, only the numerical simulation results of the middle and low frequency sound pressure levels can be kept generally close to the measured results.