Studies on V-shaped flow control devices to improve film cooling effectiveness for air-cooled turbines

Demand for highly efficient gas turbine systems has been increasing TIT (turbine inlet temperature) and this trend will continue for forthcoming carbon-neutral age, necessitating the turbine designers to invent new ideas for adequate cooling of the turbine vanes and blades with less cooling air. Film cooling is one of the most effective cooling methods and a vast number of relevant studies have been made on this topic for decades. Recently several attempts including ones by the present authors have been made to investigate effects of flow control devices placed upstream or downstream of the cooling holes to improve film cooling effectiveness, showing promising results for their application to real gas turbines. This study proposes a new flow control device (FCD). This device takes V-shaped geometry on a flat plate to enhance the attachment of injected cooling air to the surface and it is placed very close to a cooling hole for the thermal management of the device itself. To maximize the aero-thermal performance of V-shaped FCD, numerical optimization supported by k-means clustering (Sing and Yang [1]) are made, and several excellent new V-shaped devices are found. Film cooling performance of the optimized devices results are validated by the experiment using PSP method.