Design and Test of Transonic Compressor Rotor with Tandem Cascade

The stage pressure ratio in axial flow compressors and fans can be considerably increased by using suitable tandem cascades. In the tandem cascade, the gap flow from the clearance between the front and the rear blades makes it possible to control the separation induced by shock. Therefore, the tandem cascade can obtain larger turning and higher pressure ratio without the increase in excessive loss. The three-dimensional viscous flow analysis was used to design the tandem cascade and the influence of the gap flow was investigated. To confirm the concepts of the tandem cascade design, the single stage transonic compressor with tandem cascade was built and tested. The results of the compressor testing indicated that the pressure ratio of approximately 2.3 can be achieved in a single stage compressor. It was confirmed that with tandem cascades, the number of stages can be reduced compared to the conventional single cascades.