Investigation of rail inclination effects on the aerothermal performance of turbine blade squealer tips with crown holes

The purpose of the rail crown-holed blade squealer tip in heavy-duty gas turbine is to improve tip cooling and decrease gap leakage. By effectively interacting with the gap flow, the cooling air from the rail crown holes considerably lowers the leakage flow rate (LFR). Furthermore, this cooling system guarantees complete thermal protection for the cavity floor (CF) and rail crown surface (RCS). To evaluate the possible improvements of the squealer tip with rail crown holes, the pressure-side rail is inclined in this study. Heat transfer, cooling efficiency, and aerodynamic performance are assessed for two squealer tip designs (conventional and novel) and five inclined distances (−3.0 mm, −1.5 mm, 0 mm, 1.5 mm, and 3.0 mm). Results indicate that inclining the rail outward increases the coolant coverage on the CF in the novel tip, reducing heat transfer but lowering the cooling intensity. The novel configuration provides robust protection for the rail crown surface, and both inward and outward inclinations negatively impact rail cooling. In terms of aerodynamics, the LFR decreases linearly with greater inclination distances for both tip designs, and the rail crown holes are more effective in LFR control when the rail is inclined towards the inner side of the cavity.