Flow and Heat Transfer About the Blade Tip in a 1.5-Stage Turbine

Blade tips in gas turbines are exposed to high heat loads because of tip-leakage flow and the complex nature of the flow in and about the blade tip. This computational study, based on steady RANS with the shear-stress transport (SST) turbulence model, examines the flow and heat transfer about the tip region in a 1.5-stage high-pressure turbine under geometric and operating conditions relevant to land-based, electric-power-generation gas turbines. Parameters studied were adiabatic wall (q_w^''=0) and two isothermal-wall conditions (T_w= 1,000 K and 1,100 K). The adiabatic-wall temperatures (T_aw) obtained with the wall set as adiabatic were used to obtain heat-transfer coefficients for simulations with walls set as isothermal. Results obtained show how heat transfer modifies the flow in and about the blade tip region and how T_aw/T_w affect the distribution of the heat-transfer coefficients.