Slots and Groove Coupled Casing Treatment for a Transonic Compressor

The coupled casing treatments have been designed for NASA Rotor 67. These casing treatments can be regarded as the addition of a circumferential groove with the same depth as the basis axial slots, where the groove is located at different relative positions to the slots. According to the numerical results, with the basis axial slots, the stall margin of the compressor was increased by 17.51% and the peak efficiency was decreased by 0.54%. With the addition of the single groove on the basis of axial slots, the stall margin has been extended further. When the groove was added at the end of the slots, the best effects can be obtained. With this structure, the stall margin can be increased by 22.35% and the peak efficiency was decreased by 0.72%.