Experimental Investigation of Cooling Jets Mixing in a Gas Turbine Cascade

摘要

This paper presents an overview of the experimental results concerning a fall coverage film cooled vane cascade investigation. Main objectives of this study were a detailed description of the cooling jets to mainstream aerodynamic mixing process and related loss generation mechanisms, together with the generation of a data set for CFD codes validation. Experimental results have been obtained in a low speed wind tunnel for linear cascade testing. The tested blade profile is typical of a real gas turbine nozzle vane. Full coverage film cooling is achieved by means of ii injection rows fed by a single internal cavity: 3 are located on the pressure side, 5 on the suction side and 3 in the leading edge region. All tests have been performed using air as coolant fluid, matching the design momentum flux ratio; this condition corresponds to an overall mass flow ratio equal to 2.5 %. A detailed experimental investigation has been performed in order to characterize the vane performances. Tests include mean and turbulent blade to blade velocity distributions, boundary layer profiles and a detailed description of cooling jet mixing process in the near hole region of the last pressure and suction side injection rows. Similar tests have been also performed on a solid blade cascade (without injection holes).