Design of a slot-type casing treatment and its experimental validation

Steady Reynolds-averaged Navier-Stokes (RANS) of a test rotor with solid casing was simulated, and the flow field near the rotor tip was investigated. Based on several predominant flow features at the blade tip region as the rotor is operate at design state and near stall state respectively, a back chambered axial skewed-slot casing treatment was designed. The performance of the casing was then validated experimentally on a high speed test rig, showing that this casing treatment has notable capability in improving the stall margin of the test rotor, whilst the loss of efficiency is acceptable. This illustrates that the design of the casing treatment could be feasible on the basis of the rotor tip flow field with the solid casing.