燃烧室结构的热-声-振耦合特性模拟分析研究

Simulation Analysis of the Thermo-Acoustic-Vibration Coupling of Combustion Chamber Structures

在发动机运行过程中,燃烧室内部时刻发生着剧烈的燃烧,不可避免地存在热-声-振耦合作用,长期的高温高压高声强工作环境会对燃烧室结构疲劳寿命和发动机正常工作产生至关重要的影响。本文利用ANSYS-WORKBENCH软件以单向耦合的方式对燃烧室结构的热-声-振特性进行了模拟分析,即先在FLUENT模块中进行燃烧运算得到流体域温度场、压力场等,然后利用稳态热分析模块获得结构上的温度场分布,最后把得到的温度场和压力场作为预应力施加给结构,对内部填充气体的燃烧室做了有预应力的单向热-声-振耦合模态分析,也对不考虑声-振耦合的燃烧室结构做了热-振耦合模态分析,得到了8阶模态频率和模态振型。结果表明,低阶模态主要包含了弯曲模态和扭转模态,而空腔模态在较高频率才出现。此外,考虑声-振耦合作用得到的各阶模态频率比不考虑声-振耦合得到的模态频率要小。

During the aero-engine operation, the intense combustion happens inside the combustion cham-ber and the thermo-acoustics-vibration interaction exists unavoidably. The operating environ-mental under high temperature, high pressure and high acoustical level has a great influence on the fatigue life of the structure and the normal operation of the aero-engine. Simulation analysis of the thermo-acoustics-vibration of combustion chamber was done through one-way coupling by ANSYS-WORKBENCH software. At first the combustion computing was done in FLUENT module in order to obtain the data of temperature and pressure fields. Then the temperature distribution on the structure through steady thermal analysis module was obtained to feed into the pre-stress structure. Modal parameters including eight modal frequencies and eight mode shapes were identified both by one-way thermo-acoustics-vibration coupling and thermo-vibration coupling. The results show that bending and torsional modes appear at lower frequencies earlier, and the cavity modes appear at higher frequencies. In addition, modal frequencies from one-way thermo-acoustics-vibration coupling are lower than those from uncoupling.