轴流压缩系统带支板过渡段的轴对称等效方法

 航空发动机轴流压缩系统过渡段内存在厚支板,该支板造成的堵塞对过渡段的性能产生重要影响,同时也使过渡段内流动成为三维复杂流动,增加了设计难度。建立了一种等效方法,通过构造与带支板过渡段具有相似气动特性的轴对称过渡段,近似地等效原带支板过渡段,从而将复杂的三维问题简化为二维轴对称问题。首先,理论推导了带支板过渡段的轴对称等效方法;随后,通过数值模拟方法,对带支板过渡段和等效过渡段内的流动特性进行对比,结果表明等效过渡段不仅与带支板过渡段的静压分布吻合很好,并且两者具有相似的损失规律,说明等效方法能客观地反映支板对过渡段内流动的影响;最后,将轴对称等效方法应用于带支板过渡段原型的改进设计,改进设计后带支板过渡段支板与轮毂角区的大范围流动分离被消除,损失减小了41.6%。

Axisymmetric Equivalent of S-shaped Transition Duct with Struts in Axial Compression Systems

Thick struts which intersect an S-shaped transition duct in an axial compression system tend to cause blockage in the flow passage and significantly influence the performance of the duct. As there are no design rules available for them, design of a transition duct with struts involves three dimensional numerical optimization, which is rather complicated. To simplify the issue in the design phase, an axisymmetric equivalent method which can reduce the problem to two dimensional problem is established. First, the theoretical concepts of axisymmetric equivalent method are presented based on the influence of struts on the pressure field in the duct. Then, the main features of the flow field in the equivalent duct and the strutted duct are compared through numerical calculation. It is shown that the endwall pressure distribution of the two ducts agrees well, and that they exhibit similar loss variation features, which both indicate that the equivalent duct is capable of capturing the major influence of struts. Finally, the equivalent method is applied to the optimization of a baseline strutted duct with separation in the strut-hub area due to high local diffusion. The optimized duct is found to have removed the separation completely, and decreased the loss by 41.6%.