高负荷低展弦比涡轮流动机理

Flow mechanism of high load and low aspect ratio turbine

为满足固体推进剂涡轮火箭发动机高负荷、高效率、低展弦比涡轮设计要求,对发动机涡轮进行初步设计.采用哈尔滨工业大学编制的叶型编辑程序,设计单级膨胀近似为4的涡轮动静叶叶型,采用NUMECA软件对所设计的涡轮动静叶流场进行数值计算.结果表明:高膨胀比涡轮动静叶整个流道内均出现超音速流动,采用缩放通道可减小激波损失;静叶出口马赫数较高,产生的尾缘激波与相邻叶栅吸力面相交,使吸力面马赫数波动,产生逆压梯度,增大了流动损失;在动叶中,端壁附面层内二次流沿壁面汇聚到吸力面中部,使吸力面中部损失增大.

To satisfy turbine design requirements for solid propellant air-turbo-rocket,a high load,high efficiency and low aspect ratio turbine was primarily designed.The stator and rotor profiles of the turbine whose expansion ratio was about four was primarily designed by using the profiles edit program compiled by Harbin Institute of Technology.The flow fields of the stator and rotor were simulated with the NUMECA software.Results indicate that supersonic flow exists in the stator and rotor flow-path of high expansion ratio turbine,and shock wave loss can be reduced with converging-diverging flow-path.The outlet Mach number of stator cascade is relatively high,where the trailing edge shock wave intersects with suction surface of the neighboring cascade,so that suction surface Mach number fluctuates,and an adverse pressure gradient forms and flow loss increases.In rotor cascade,the second flows in the end wall boundary layer collect together to the mid section of suction surface which leads to the flow loss increasing.