Design and experimental and theoretical investigation of a transonic trailing edge cooled turbine guide vane

Abstract

Inlet guide vanes (IGV) of high temperature gas turbines require an effective trailling edge cooling. But this cooling influences significantly the aerodynamic performance caused by the unavoidable thickening of trailing edge and the interference of the cooling flow with the main flow. Generally the blade trailing edge losses belong to the most importantpenalties for the overall turbine stage efficiency. They are functionof the trailing edge thickness and the base pressure and may amount to 30% of the losses for cascades operating at transonic outlet Mach numbers. It is also known that the ejection of coolant flow from the trailing edge affects considerably the base pressure and thereby the trailing edge losses. Most investigations refer to coolant flow ejection through the trailing edge but the actual tendency seems to favour the ejection of the coolant from the pressure side just ahead of the trailing edge. The obvious advantage is the reduction of the trailing edge thickness. But this may be compensated by the modified pressure distribution resulting in a reduced lift of the blade.