燃烧室热-声-结构耦合特性研究

Research on the Characteristics of Thermal-Acoustic-Structural Coupling in a Combustion Chamber

航空发动机燃烧室的热释放、声波动以及流体扰动与结构振动之间的耦合作用对结构破坏产生重要影响。应用有限元分析软件建立数值模型,从能量角度分析了热声耦合产生的根源及其作用机理,建立了热-声-结构单向耦合机制,完成了燃烧室薄壁结构预应力模态分析、谐响应分析与谱分析,得到了耦合条件下的结构动力学特性。通过试验数据与模拟结果的对比研究,得出耦合作用产生的根源为燃烧不稳定性,火焰波动对速度场、压力场、密度场等的形成与发展具有重要影响;热载荷对结构振动影响较大,且对高频段影响比低频段大;声压力载荷对结构振动影响较小,且在某些频率下使结构振动频率减小。工作对燃烧室设计等具有重要实际价值。

Couplinglof heat release, acoustic fluctuation, fluid perturbation and structural vibration in an aero -engine combustion chamber can produce continuous alternating loads which have significant impacts on failure of combustion chamber. Finite element analysis software is applied for establishing numerical models and solving. The root causes and mechanism of thermal-acoustic coupling are discussed by using energy method. One way coupling of thermal--acoustic- structure is developed and structural dynamic characteristics of the walls are studied through prestressed modal analysis, harmonic response analysis and spectrum analysis under coupling. The conclusion that combustion irritability induces multi- physics coupling is obtained by comparative analysis of the experimental datas and simulation results. Flame fluctuation has an significant impact on the formation and development of veloclty field, pressure field, denslty field and other flow fields. Thermal loads have a large impact on structural vibration, and the effect is greater in high frequeucies than in low frequencies. Acoustic pressure loads have little effects on structural vibration and they make frequency decrease at certain frequencies. These works have important practical values for design of combustion chambers.