Experimental Investigation of Film Cooling With Ejection From a Row of Holes for the Application to Gas Turbine Blades

The adiabatic wall effectiveness and the heat transfer coefficient is determined experimentally on a flat plate downstream of a row of inclined circular ejection holes. The measuring technique provides local values in downstream direction and averaged values in lateral direction. The ejection geometry is kept constant, i.e., ejection angle β = 35 deg, spacing to diameter ratio of ejection holes s/d = 3. The range of flow parameters corresponds closely to the conditions encountered on gas turbine blades. The main flow Mach number varies from 0.3 to 0.9, the mass velocity ratio from 0.1 to 2.0. Two favorable pressure gradients in the main flow are applied and several ratios of main flow boundary layer displacement thickness to ejection hole diameter. The main flow boundary layer upstream of the ejection is laminar and turbulent.