Film Cooling With Swirling Coolant Flow on a Flat Plate and the Endwall of High-Loaded First Nozzle

This paper describes an experimental study on the film cooling effectiveness of circular and fan-shaped film cooling holes with a swirling film coolant injected through a flat plate and the endwall of a high-loaded first nozzle. The experiments were conducted using a flat plate wind tunnel and a two-dimensional vane cascade, which is designed based on the first-stage vane of an Energy Efficient Engine (E³) studied under a NASA project. The film cooling effectiveness on a flat plate wind tunnel and the endwall of the enlarged first nozzle of the E³ turbine was measured using pressure sensitive paint (PSP) techniques. The experimental results indicate that the film cooling effectiveness of a circular hole improved by increasing the angle θ of two impinging jets inside the cavity, which are used both for cooling the internal wall and generating a swirling motion in the film coolant. In contrast, it was found that there exist optimal jet angles of θ = 20° for a circular film cooling hole, θ = 5–10° for a flat plate wind tunnel test, and θ = 15° for the cascade test conducted using a fan-shaped film cooling hole. Thus the new film cooling method using swirling cooling air has been demonstrated to maintain high film cooling effectiveness even under such a complicated flow field.