Experimental investigation of the effect of the clearance size on aerodynamic characteristic in turbine cascade

The aerodynamic parameters on middle clearance plane and the upstream to downstream of the conventional linear turbine cascades with the clearance size is 0.036 m are measured in a low-speed wind tunnel, and the test data are compared with the data of Dr. Hongyan Huang who measured the same turbine cascade with the clearance size of 0.023 m. By analyzing and discussing the tested result, in the present paper we think that the tip clearance would take the secondary flow from hubwall to tipwall in the flow passage, this improves the flow at lower half part of the passage but deteriorated the flow at upper half part. The leakage flow would be more near the tipwall with a larger clearance size. This enhances the shear effect of the wall, so the total pressure loss with a larger clearance size is more than that with less clearance size.