有声腔推力室的声学振型及其阻尼特性研究

Numerical Study on Acoustic Modes and Their Damping Characteristics in a Thruster Chamber with Resonators

关键词:  1/4波长管声腔  推力室  声学振型  阻尼特性  抑制作用  数值定容弹

Key words:  Quarter-wave resonator  Thruster chamber  Acoustic mode  Damping characteristic  Suppression  Numerical constant-volume bomb

摘要:

为确定多声学模态压力振荡条件下带有1/4波长管声腔推力室的声学振型及其阻尼特性，揭示1/4波长管声腔对推力室压力振荡的抑制作用机理，对有声腔推力室和无声腔推力室进行近圆周壁面的定容弹激励仿真，激发了多模态的声学振型，给出了推力室压力分布的时空演化，并采用半带宽法定量评价每个激发声学振型的阻尼特性。结果表明：1/4波长管声腔成功抑制了目标振型（一阶切向振型）压力振荡，大幅度减小其幅值，而不是大幅度增加其半带宽，但可能增强其它非目标振型的压力振荡。声腔通过削弱目标振型波峰波谷压力差、声腔入口漩涡和增加壁面面积等三种方式来抑制目标振型压力振荡，主要以前者为主，前者旨在降低目标振型幅值，后两者是增加其半带宽。

Abstract:

In order to determine acoustic modes and their damping characteristics in a thruster chamber with quarter-wave resonators under multi-acoustic modes pressure oscillations condition and reveal the suppression mechanism of quarter-wave resonators on pressure oscillations， the acoustic modes and their damping characteristics of a chamber without resonator and a chamber with quarter-wave resonators were numerically predicted by imposing numerical constant-volume bomb at the region near the circumferential side-wall. Multi-acoustic modes were excited and the temporal and spatial evolution of pressure contours were performed. The damping characteristics of each excited mode were evaluated by half-power bandwidth method. The results show that pressure oscillation of the target mode （the first tangential mode） is successfully retrained by quarter-wave resonators. The amplitude is reduced greatly， while the half-power bandwidth increases slightly. But pressure oscillations of other acoustic modes may be enhanced. Quarter-wave resonators suppress pressure oscillations of the target mode by three ways： reducing the difference in the crest and trough pressure of target acoustic mode， producing vortex in the inlet of resonators and increasing wall surface. The form one is the major mechanism， which will reduce the amplitude of the target mode. The latter ones will increase the half-power bandwidth.