In high-pressure turbines, there is a large difference in temperature between the mainstream and the turbine blade surface. Most of the turbine blade tip heat transfer studies were conducted under the assumption that the Over-Tip-Leakage (OTL) flow field is independent of the wall thermal condition. Recent numerical and experimental studies have revealed that the two-way coupling effect between aerodynamics and heat transfer should not be neglected. The heat transfer coefficient obtained by the conventional method is not able to match the realistic engine condition accurately. This study investigates the impact of the wall thermal boundary condition on the tip cooling performance of squealer turbine blades. The RANS CFD result was validated against experimental tip heat transfer data obtained from a high-speed test rig with the effect of high-speed relative casing motion. The aerothermal performance for both uncooled and cooled squealer tips was studied at two different gas-to-wall temperature ratios, 1.7 and 1.1; the reference temperature is 204 K. It was found that the location and strength of cavity vortices varied with different wall thermal boundary conditions, leading to different signatures in tip heat transfer and cooling performance. It is recommended that the experimental heat transfer data and film cooling effectiveness obtained at the near-adiabatic wall boundary condition should be corrected before their application to the tip cooling design process. It would be more reliable to match the wall-to-gas temperature ratio during the tip experimental study.

Ceramic matrix composites (CMCs) are increasingly utilized in aero-engine blades owing to their exceptional mechanical and thermal properties. However, variability in material components and processing technologies leads to dispersion in equivalent performance, potentially affecting the reliability of CMC turbine blades. Focused on unidirectional fiber-reinforced CMCs, the present study integrates numerical simulations and neural network models to investigate the influence of mesoscale geometric and thermal parameter variabilities on the dispersion of the equivalent thermal conductivity (ETC). Based on the obtained probability density function of ETC, further quantitative analysis is conducted to assess the effect on the maximum surface temperature, high-temperature area proportion, temperature variation range, and temperature standard deviation of turbine blades. The results indicate that the ETC is most predominantly sensitive to the fiber diameter. The coefficient of variation for the axial-direction ETC remains identical to the input parameters while that for the normal-direction ETC is significantly amplified under the nonlinear heat transfer features. The ETC dispersion induces a 14% fluctuation in the high-temperature area proportion at the blade surface and a maximum temperature variation over 10 K at the leading edge region.