燃烧室热-声-固耦合数值模拟研究

摘要

To decrease emission of NOx,lean premixed combustor is applied for gas turbine.This lead to the combustion instability and structural fatigue problem occurs on the combustion chamber.Finite element analysis software is applied for establishing numerical models of combustion chamber.The impact of inlet velocity on the numerical simulation is contrasted and analyzed with different grids used on model.The one-way and two-way couplings are used to analyze the thermal-acoustic-structural coupling characteristics.The comparison of experimental data and results of numerical simulation analysis shows that grid quality has an effect on computational accuracy in some degree and inlet velocity plays an important role on the numerical simulation results.Compared with the acoustic pressure load, thermal load has a greater effect on the natural frequencies and modal shapes, besides, the effect is greater in high frequencies than in low frequencies. The numerical simulation results of two-way coupling are closer to the actual situations. A lot of reference value for improving stability and design of resistance to fatigue caused by thermal-acoustic-structural coupling in combustion chamber are presentd.%为减少NOx等污染物的排放,现代燃气轮机多采用贫油预混燃烧技术,由此产生较为突出的燃烧振荡与燃烧室结构疲劳问题.应用有限元软件建立燃烧室数值模型,优化燃烧室模型网格;对比分析进气速度对数值模拟结果的影响;运用单向耦合与双向耦合方法计算分析了燃烧室热-声-固耦合特性.研究表明:网格质量在一定程度上影响计算精度,进气速度对数值模拟结果影响较大;相对于声压载荷,热载荷对结构固有频率和振型影响较大,特别是在高频段;双向耦合较单向耦合数值模拟结果与实际情况更为接近.热-声-固耦合分析方法对发动机燃烧震荡机理研究及其抗热-声-固耦合疲劳设计具有应用参考价值.