论文部分内容阅读
低压涡轮既是飞机进场着陆时发动机的重要声源,也是发动机中对效率要求很高的部件之一,为了实现低压涡轮低噪声的设计目标必须同时兼顾气动性能指标。研究给出了高效低噪声低压涡轮气动-声学三维优化的思路,即首先通过计算流体力学(CFD)定常计算评估三维设计变化对气动性能的影响;然后利用非定常CFD方法与三平面压力模态匹配(TPP)方法的结合来评估其降噪的效果与非定常气动影响;最后确定最佳的设计方案。以GE-E3(Energy EfficientEngine)低压涡轮末级为算例,数值模拟了导叶倾斜作为低压涡轮降噪措施的潜力。计算结果表明,正倾斜导叶角度小于19°时单级涡轮气动性能较直列叶栅要好,效率最大提高了0.3%。对单音噪声级的评估指出,正倾斜由于改变了导叶的尾迹特征,涡轮级噪声水平是增大的,因此不能作为有效的降噪策略。数值研究的结果表明CFD方法能够同时反映出叶片三维设计的细节变化对气动和噪声级的影响,可以作为三维气动-声学优化的手段。
Low pressure turbine is not only an important engine of the aircraft landing approach, but also one of the most efficient parts in the engine. In order to achieve the design goal of low pressure turbine with low noise, aerodynamic performance index must be considered. The idea of three-dimensional aerodynamic-acoustic optimization of a low-pressure, high-efficiency and low-pressure turbine is given. The first step is to evaluate the effect of three-dimensional design changes on the aerodynamic performance by CFD. Then, the unsteady CFD method and three- Matching (TPP) method to evaluate the effect of noise reduction and unsteady aerodynamic effects; the final determination of the best design. Taking the final stage of GE-E3 (Low Pressure Turbine) as an example, the guide vane inclination is numerically simulated as potential of low pressure turbine noise reduction. The calculated results show that the aerodynamic performance of the single stage turbine is better than that of the straight cascade when the angle of the guide vane is less than 19 °, and the maximum efficiency increases by 0.3%. The evaluation of the monophonic noise level indicates that the positive slope increases the noise level of the turbine stage due to the changed wake characteristics of the guide vane, and therefore can not be used as an effective noise reduction strategy. The numerical results show that the CFD method can simultaneously reflect the details of the three-dimensional design of the blade on the aerodynamic and noise levels can be used as a three-dimensional aerodynamic optimization method.