Executive Summary : | Gas turbines are used to a great extent in aircraft-propulsion, land-based power-generation, and in marine applications. The efficiency of a gas-turbine is directly proportional to the temperature of the gas at the inlet to the turbine. However, this temperature is limited by the metallurgical limit that is due to the melting temperature of the blade material. Therefore, the blades of a gas-turbine are cooled using various techniques such as film cooling, impingement cooling, pin-fin cooling in the various sections of the turbine blade. In the present proposal, the focus is on the trailing-edge portion of the turbine-blade where pin-fin cooling is employed. The trailing-edge portion is a thin and narrow converging passage that typically consists of circular short pin-fins around which the coolant flows to extract heat from the hot turbine gases through the walls of the blade. A great number of studies can be found in the literature that analyzed the various aspects of pin-fin cooling using experimental and numerical techniques. While most of the studies are limited to stationary blades, the numerical studies are limited to a large extent to Reynolds-averaged Navier-stokes (RANs) based simulation techniques. The present work, proposes to evaluate the flow and heat transfer characteristics in the trialing-edge portion of the gas-turbine blade under realistic conditions with eddy-resolving techniques such as the large-eddy simulation (LEs). In this research, it is proposed to perform LEs studies in the converging passage of the trailing-edge portion of the gas-turbine blade under realistic flow conditions. The novelty of the proposed study is the consideration of conjugate heat transfer, while the turbulent flow is resolved and the inclusion of turbine blade rotation effects into the simulation. Further, the effect of different shapes of the pin-fins will be evaluated to identify best cross-sectional shape that will provide enhanced heat transfer with lowest flow losses. The open-source computational fluid dynamics software OpenFOAM will be used to perform the simulations. As the software is open-source there are no licensing costs involved and the solver can also be tailored according to the simulation needs during the course of the project. The proposed research will have the following significance and contribution to the field of gas-turbine cooling: (1) By incorporating the conjugate heat transfer and rotation effects, the flow and thermal characteristics in realistic gas-turbine trailing-edge will be better resolved and the models thus developed will be more accurate. (2) The obtained results will be disseminated through conference presentations, peer-reviewed journal publications and by discussing and sharing the same with other interested researchers in the field, and with organizations like Gas Turbine Research Establishment (GTRE). |