Advances in the Aerothermal Performance Enhancement of Turbine Blade Tip Configurations

A clearance necessarily exists between the blade tip and the casing in turbines. A leakage flow, formed by the accelerated gas through the tip clearance, is a major cause of turbine stage efficiency loss. Severe heat loads on the blade tip surface also result from a leakage flow, a primary cause of blade damage. Although the understanding of leakage flow mechanisms is mature after years of research, the continuous rise in turbine inlet temperature, pursuing higher engine thrust, requires more effective cooling methods for the blade tip region. This paper presents a review of research on three fundamental tip structures (flat tip, squealer tip, and winglet tip) to explain their design concepts, analyze their respective flow mechanisms as well as heat transfer characteristics, and introduce various modified designs. Various film cooling arrangements applied to these tip structures are examined to identify effective strategies that strengthen the advantages of structural optimization. In view of engineering applications, this paper reviews research on unsteady wake interactions as the aforementioned framework, hoping to provide readers a more comprehensive understanding.