Strength variation of gas cooling turbine blade pin‐fin with different array

Abstract

As an important measure of cooling, the pin fin array has been widely used in the cooling blade of turbine. However, most of the cracks in turbine blade are found near the pin fin due to stress concentration. In order to study the strength variations of pin fin in various shapes and with various longitudinal and transverse pitches, this paper establishes 10 rectangular, 3 elliptical and 1 diamond‐shaped slab models of pin fin array. The results indicate the existence of high stress area and low stress area around the pin fin. In the rectangular pin fin model, the maximum equivalent stress is detected on the side perpendicular to the load applied, the low stress area is on the side parallel to the load applied, and the high and low stress areas are semi‐elliptically distributed along their own track. For a rectangular pin fin array, the equivalent stress along each side of the bottom first increases and then decreases, with the maximum equivalent stress at the corners and the minimum at mid‐point of each side; along the height direction, the minimum equivalent stress of a rectangular pin fin array is near the ends while that of a square pin fin array is at the mid‐points. Under the same conditions, the stress of the rectangular pin fin array decreases with the decrease of the aspect ratio (h1/b). The position of the maximum stress around the elliptical pin fin array varies from the two axis ratio (a/b). When a/b is 2, the maximum equivalent stress around the bottom is at the positions with a horizontal angle of 75°/120°/255°/300°; when a/b is 1, the maximum equivalent stress is at the positions with a horizontal angle of 60°/135°/240°/315°; and when a/b is 0.5, the maximum equivalent stress is at the positions with a horizontal angle of 45°/150°/220°/330°. Under the same conditions, the stress of a round pin fin array is smaller than that of a square one. In all the analytical models, the diamond‐shaped pin fin array presents the largest equivalent stress and the highest stress concentration.