Investigation of burnout effect in turbine blade tip leakage at transonic conditions: a numerical study

In the aviation industry, turbine blade tip leakage significantly impacts the economy due to aerodynamic losses in the turbine. The tip leakage fl ow increases when the tip surface is exposed to high heat loads from the burnout effect, contributing to nearly 30% of the total loss in the turbine stage. This study numerically investigates two-dimensional fl at tip and burnt-out tip models under different fl ow accelerations at transonic conditions. Variations in the discharge coefficient are examined for different pressure ratios across the tip gap. Flow and shockwave patterns for various blade tip geometries are obtained and analyzed. The burnt-out tip notably increases tip leakage, and a significant decrease in turbine efficiency is observed beyond a critical burnout limit. The quantified losses at different stages of blade tip burnout are used to predict the effective operational life of the blade. A correlation is developed to relate the non-dimensional tip-leakage fl ow parameters to the normalized blade-tip geometry.