Heat/Mass Transfer Characteristics on Turbine Shroud with Blade Tip Clearance

Abstract: The present study is conducted to investigate the local heat/mass transfer characteristics on the shroud with blade tip clearances. The relative motion between blade and shroud is neglected, and four‐bladed linear cascade is used in this study. naphthalene sublimation method is employed to determine the detailed local heat/mass transfer coefficients on the surface of shroud. The tip clearance is changed from 0.66%t to 2.85%t of the blade chord length. The flow enters the gap between the blade tip and shroud at the pressure side due to the high pressure side due to the high pressure difference. Therefore, the heat/mass transfer characteristics of the shroud are changed significantly from those with endwall. A first, high heat/mass transfer occurs along the profile of blade a the pressure side due to the entrance effect and acceleration of the gap flow. Then, the heat/mass transfer coefficients on the shroud increase along the suction side of the blade because tip leakage vortices are generated and interact with the main flow. The results show that the heat/mass transfer characteristics are changed largely with the gap distance between the tip of turbine blade and the shroud.