Design Support Numerical Code for Stall Flutter Analysis.

本研究旨在开发一个数值计算程序，使我们能够预测失速压气机和涡轮叶栅的非定常气动特性及其失速颤振极限。为此，对目前用于分析旋转失速非定常流动的数值代码进行了扩展，使其能够处理叶片旋转或平动振荡的叶栅流动。利用该程序，对典型压气机叶栅中各叶片绕平均弧度线中点旋转时的失速流动进行了一系列数值分析。减小频率和叶间相位角变化很大，发现失速颤振的非定常激励力矩与旋转失速沿叶栅的传播密切相关。数值程序也应用于振荡涡轮叶栅的分析。以大偏转角喷管叶栅的旋转振荡和大交错、小转角转子叶栅的平移振荡为例进行了分析。在大范围的非定常振荡参数下，得到了一系列非定常气动特性。此外，还对压气机叶栅数值分析中使用的旋转振荡叶栅进行了叶栅风洞试验。测量了振动叶片表面的非定常压力分布，计算了叶片的非定常气动功。实验结果与数值计算结果吻合较好。

This study aims to develop a numerical calculation code which enables us to predict the unsteady aerodynamic characteristics of the stalled compressor and turbine cascades as well as their stall flutter limits.For this end, the numerical code which authors have used so far to analyze the unsteady flow of rotating stall was extended so that it can deal with the flow through the cascades, of which the blades oscillate rotationally or translationally.With use of this code, a series of numerical analyzes of the stalled flow through a typical compressor cascade with each blade oscillating rotaionally around the mid-point of the mean camber line was carried out. The reduced frequency and the inter-blade phase angle were changed in wide varieties and it was found that the unsteady exciting moment of the stall flutter was closely connected with the propagation of rotating stall along the cascade. The numerical code was also applied to the analysis of oscillating turbine cascades. Rotational oscillation of a nozzle cascade with large deflection angle, and translational oscillation of a rotor cascade with high stagger and low turning angles were selected as examples for the analysis. A series of unsteady aerodynamic characteristics were obtained for wide range of unsteady oscillation parameters.Further, a cascade wind-tunnel test of the same rotationally oscillating cascade as used in the numerical analysis of the compressor cascade was performed. Unsteady pressure distributions on the oscillating blade surface were measured, and the unsteady aerodynamic works given to the blades were calculated. The experimental results agreed well with those predicted by the numerical calculation.