In order to suppress the tip leakage loss and increase the isentropic efficiency in a radial turbine with low aspect ratio blade, a new coupling flow control technology including casing groove and NACA blade profile is proposed and optimized numerically. The coupling effects of casing groove size L_S, groove number Num_slot, maximum thickness location of profile MLT and leading parameter of profile LP on isentropic efficiency of a radial turbine are obtained with Design of Experiment (DOE) and response surface model. A genetic optimization is achieved and the coupling flow control mechanism is revealed. Complex variation of isentropic efficiency is observed with the coupling effect of groove size and groove number, and maximum isentropic efficiency variation of 0.6% is obtained with the increase of L_S when Num_slot is 3. The coupling effect between L_S and LP, is also significantly influenced by groove number. The lower limit of LP for maximum isentropic efficiency is decreased from 7 to 3 with the increase of groove number. The optimization result illustrates that the isentropic efficiency can be increased by 0.9% at design point when the L_S, Num_slot, MLT and LP are 0.8 mm, 2, 0.1, and 0.8 respectively. A maximum isentropic efficiency increment of 2.0% is also found when total pressure ratio is 2.1. The optimal casing groove forms a flow opposite to the tip leakage flow to suppress the impact range of the secondary flow near suction surface. At the same time, the optimal NACA profile also decreases the tip leakage velocity near trailing, suppresses the tip leakage vortex generation, and reduces the trailing edge loss.

为了抑制低长径比叶片径向涡轮的叶尖泄漏损失并提高其等熵效率，提出了一种新的耦合流控制技术，包括壳体槽和NACA叶片轮廓，并对其进行了数值优化。套管槽尺寸L _S，槽号Num_槽，型材MLT的最大厚度位置和型材LP的前导参数的耦合效应利用实验设计（DOE）和响应面模型获得了径向涡轮的等熵效率。实现了遗传优化，揭示了耦合流控制机制。的等熵效率复杂变化与槽的大小和槽数，以及0.6％的最大等熵效率变化的耦合效应观察到与增加获得大号_小号时货号_时隙为3之间的耦合效应大号_小号和LP，是槽数也显着影响。LP的下限随着槽数的增加，最大等熵效率从7降低到3。优化结果表明，当L _S，Num _slot，MLT和LP分别为0.8 mm，2、0.1和0.8时，等熵效率可以在设计点提高0.9％。当总压力比为2.1时，最大等熵效率增量为2.0％。最佳的套管凹槽形成与尖端泄漏流相反的流，以抑制二次流在吸力表面附近的影响范围。同时，最佳的NACA轮廓还降低了尾部附近的尖端泄漏速度，抑制了尖端泄漏涡流的产生，并减少了后缘损耗。