非均匀流场时-空演化下叶片气动弹性响应触发机制

Inlet distortion and inlet-aeroengine compatibility are great challenges in the field of aeroelasticity of future aero-engines for both military and civil use. The major difficulties lie in two aspects: (1) the time-spatial propagation of the unsteady flow fields in the inlet/fan system under the non-uniform inlet working condition is not fully clarified or understood, and (2) no effective model is available to fully describe the response mechanism of blade aeroelasticity due to the non-uniform and unsteady aerodynamic forces. Because of the above two issues, the research on the inlet-aeroengine compatibility is still dependent on regular methods. This proposal will focus on thoroughly exploring the time-spatial propagation of the unsteady flow fields in the inlet/fan system under the non-uniform inlet working condition and revealing the triggering mechanism of the blade aeroelastic response induced by the non-uniformity and unsteady aerodynamic forces. With the help of a) the integrated expedited calculation method based on the viscous body-force model of the combining internal/external flow, and b) an accurate aeroelastic response fast-simulation approach based on the time transform method and the Harmonic Balance method, and c) the techniques of three-dimensional fluid-structure dynamic measurements based on the non-contact wireless telemetry, the effect of different aerodynamic and structural parameters on the unsteady flow fields and aeroelastic induction will be fully discussed. The key parameters will be identified and the variation rules will be summarized. The final purpose is to establish an effective analytical model and further develop an innovative prediction approach for the blade aeroelastic response, especially for non-uniform inlet working conditions.

进气畸变及进气道/发动机相容性问题是未来军/民用航空发动机气动弹性研究所必须面对的一大难题。其难点在于：1）畸变非均匀进气边界下，进气道／风扇内部非定常流场时-空演化的物理图景不明晰；2）对于非均匀、非定常气动力诱导下的叶片气动弹性响应机制也没有建立模型描述。上述两类问题的存在，导致进/发相容性问题的研究仍严重依赖常规方法。本项申请将聚焦于探索非均匀边界下进气道/风扇内部非定常流场时-空结构的演化规律，揭示非均匀、非定常气动力诱导下的叶片气动弹性响应机制；基于内外流一体化粘性体积力模型快速流场数值模拟方法、时域时间交换和频域谐波平衡气动弹性响应数值模拟法以及非接触无线遥测三维流固耦合动态测试等技术措施，探索不同气动参数、结构参数对非定常流场以及气动弹性诱导的影响，提炼关键参数并总结其变化规律，建立非均匀边界下叶片气动弹性响应的分析模型，并最终发展非均匀进气边界下叶片气动弹性响应的预测方法。

边界层抽吸式（BLI）推进系统在降低耗油率和提高效率方面有着巨大的潜力，然而，该技术的应用同时也使风扇叶片时刻工作在非均匀性和强非定常性的来流条件下，叶片极有可能受到进气畸变引起的低阶激励而发生振动，因此非均匀进气边界条件下风扇叶片的气动弹性问题亟需解决。围绕上述问题，本基金通过数值及实验等手段开展了以下两方面工作：1) 非均匀进气边界下进气道/风扇内部非定常流场的时-空演化物理图景描述；2) 非均匀、非定常气动力诱导下叶片气动弹性响应的触发机制及模型研究。在研究过程中本基金发展了一些相应的关键科学方法及技术，包括一体化分布式力源体积力模型的快速流场数值计算方法、时域解耦和耦合的气动弹性响应快速数值模拟方法以及基于旋转测试模块的叶片振幅采集等。基于以上研究手段，本项研究最终明晰了非均匀边界下进气道/风扇内部非定常流场的时-空演化规律，揭示了非均匀、非定常气动力诱导下的叶片气动弹性响应机制，探究了不同畸变范围及强度对气弹响应的影响机理，明确了导致叶片振动发生的主要因素。综上，本项研究针对非均匀进气边界下进气道/风扇流场时-空演化对叶片气动弹性响应触发机制已具备较为清晰的认识，同时本基金所发展的进气道/风扇一体化快速计算方法以及气动弹性快速数值及分析方法，能够有效的应用于进气道/风扇一体化研究以及非均匀进气边界下风扇叶片气动弹性响应问题的快速预测。