Unsteady Numerical Investigation on Film Cooling Characteristics of the Trailing Edge Cutback With Upstream Cylinder Hole

Abstract The trailing edge cutback is often applied when designing the film cooling structure of a high-pressure turbine. Previous studies have demonstrated strong unsteady film mixing process which is indeed influenced by the vortex shedding from the pressure side lip. Thus, adiabatic film cooling effectiveness on cutback rapidly declines at streamwise direction. To obtain high film cooling performance, this paper arranges a cylinder hole on pressure side upstream of the trailing edge cutback flat-plate model. The film cooling characteristics of combined configuration are investigated with unsteady numerical method. DES turbulence model has been proved to capture the vortex shedding well. The mainstream Reynold number is Rem = 360000 based on the length from inlet to lip. The total coolant-to-mainstream blowing ratio is M = 0.5 and cylinder hole is arranged at three different positions (X/H = −4, −6, −8). Firstly, film cooling performance of two configurations (cutback, cutback with a cylinder hole at X/H = −6) are compared. The results indicate that the mainstream temperature and velocity greatly reduce due to hole coolant ejection. The vortex shedding downstream of lip is weakened contributing to less film mixing on the trailing edge cutback. The lateral-averaged adiabatic film cooling effectiveness increases especially downstream of cutback. Then three combined configurations of hole at different positions show that all configurations can improve film cooling performance of the trailing edge cutback. When cylinder hole is arranged closer to lip, adiabatic film cooling effectiveness increases more.