Heat Transfer and Pressure Drop Measurements in a Rib Roughened Leading Edge Cooling Channel

In order to enhance convective heat transfer in internal cooling channels, ribs are often used to manipulate the flow field and to benefit from their effect on thermal performance. This paper presents results from an experimental investigation into pressure loss and heat transfer in a smooth and a ribbed leading edge channel of a gas turbine blade internal cooling system. To model the cross section of a realistic leading edge cooling channel both the suction side and the leading edge of the blade profile are designed as curved walls with constant radii. The pressure side as well as the web is approximated by planar walls. For the ribbed channel, 45°-ribs related to the flow direction are placed on the pressure and the suction side with the normalized rib height e/d_h = 0.10. Experiments have been carried out for the smooth and the ribbed channel. The flow rate was varied to cover a Reynolds number range from 20,000 to 50,000. The heat transfer has been determined using the transient liquid crystal method. Additional numerical simulations using the SST turbulence model were carried out to analyze the flow field in the channel. The computations were used for further interpretation of the experimental investigations, especially to determine the temperature field and velocity field and therefore the bulk temperature within the test section.