Investigation of heat transfer and fluid flow over pocket cavity in the rear part of gas turbine

The pocket cavity is generated at the transition part between the low pressure turbine (LPT) and outlet guide vane (OGV) in a gas turbine engine. Because the important connection with OGV, the heat transfer and fluid flow need to be investigated and analyzed. In the present work, a simplified triangular pocket cavity is built and heat transfer and fluid flow are investigated experimentally and numerically. Liquid Crystal Thermography (LCT) is employed to measure the heat transfer over the pocket surface with Reynolds number ranging from 54,054 to 135,135. In addition, two fillets with different radii are designed to investigate the flow structures over the pocket surface. The turbulent flow details are provided by numerically calculations based on the commercial software Fluent 15.0 with a validated turbulence model. Based on the results, the highest heat transfer value is located in the downstream boundary of the pocket cavity where the strongest flow impingement happens. The smaller fillet radius presents a higher heat transfer peak value and also induces stronger recirculating flow inside the pocket cavity. Considering the design requirement in the rear part of a gas turbine, i.e., to decrease the heat transfer peak value, a larger fillet radius is recommended for practical design. The heat transfer and flow details also provide a reliable reference for gas turbine engine design.