INFLUENCE OF RIBS ON INTERNAL HEAT TRANSFER AND PRESSURE DROP IN A TURBINE BLADE TRAILING EDGE CHANNEL

Convective cooling inside the internal passage of a turbine blade trailing edge is often insufficient at the sharp corner, when cutback slot cooling is not present. This study investigates the convective heat transfer and pressure drop in a simplified trailing edge internal channel. The internal passage has been modeled as a right triangular channel with a 9. angle sharp corner. Heated baseline (with no internal features) and ribbed copper plates have been examined via infrared thermography. A uniform heat flux heater is installed beneath the plates, and non-uniformities in the heat flux due to conduction is corrected by a RANS conjugate heat transfer calculation. The numerical simulations were validated beforehand by experimental results of mean velocity, friction factor, and temperature fields. Nusselt number distributions show that convective heat transfer is significantly enhanced with ribs, and closely coupled with the vortical flow structure. Heat transfer at the corner is increased by more than a factor of two with ribs, due to secondary flow towards the corner. Although the pressure loss and friction increase slightly, the overall thermal performance, represented by the average Nusselt number with respect to the friction factor, increases by a factor of two with the ribs.