非轴对称端壁造型在大径向落差长度比压气机中介机匣中的应用

Application of non-axisymmetric endwall contouring in compressor intermediate duct with a large radius change to length ratio

  • 摘要: 为了探索非轴对称端壁造型在大径向落差长度比压气机中介机匣中的应用潜力,本文采用数值仿真方法研究了该类中介机匣的气动特性以及轮毂非轴对称端壁造型对中介机匣流动特性和节流特性的影响。结果表明:中介机匣内部流动损失和出口流场畸变主要来源于支板角区分离,且均随流量的增加而变强,而支板角区分离范围的变化趋势则相反。 由此,本文提出一种基于三角函数的非轴对称端壁造型方法,通过改变支板附近轮毂型线的曲率和轴向压力梯度从而有效削弱支板角区分离强度。同时,所采用的非轴对称端壁造型并未影响中介机匣总压恢复系数随流量增加而下降的变化规律,而在中介机匣大流量工作范围内(相对流量不低于0.6)能够减弱中介机匣内部二次流的强度,以实现抑制中介机匣的流动损失,起到改善出口流场畸变和中介机匣性能的作用。

     

    Abstract: In order to explore the application potential of non-axisymmetric endwall contouring (NAEC) in the compressor intermediate duct (CID) with a large radius change to length ratio, the aerodynamic characteristic of this type of compressor intermediate duct has been numerically studied in the present work, and the effect of the non-axisymmetric endwall contouring on the hub of the compressor intermediate duct has been investigated in terms of flow and throttle characteristics. The results show that, the flow loss and outlet flow distortion of the compressor intermediate duct are mainly originated from the corner separation of the strut. With the increase of the flow rate, the flow loss and outlet flow distortion are enhanced, which is opposite to the change of the strut corner separation. On this basis, this study has proposed a novel approach for non-axisymmetric endwall contouring using trigonometric functions. By adjusting the curvature of the hub contour near the strut and modifying the axial pressure gradient, this method can effectively reduce the intensity of the corner separation around the strut. Moreover, the implementation of such a non-axisymmetric endwall contouring does not compromise the decreasing trend of the total pressure recovery coefficient with increasing flow rate. Within a wide range of large flow rates (with the relative flow rate not lower than 0.6) in the compressor intermediate duct, this method can successfully attenuate the intensity of secondary flows within the compressor intermediate duct, reduce flow losses, and improve both the flow uniformity at the exit as well as the overall performance of the compressor intermediate duct.

     

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