倾斜30°锥形喷孔气膜冷却的流动和传热实验研究

AN EXPERIMENTAL STUDY ON FLOW AND HEAT TRANSFER AROUND A SINGLE CONE-SHAPED FILM COOLING HOLE WITH INCLINED ANGLE OF 30°

关键词:  涡轮叶片  热效率  薄膜冷却  气体冷却  喷流试验

Key words:  Turbinne blade  Thermal efficiency  Film cooling  Gas coolinng  Jet test

摘要:

对流向倾角为３０°、锥顶角分别为１５°和３０°的锥形气膜冷却喷口射流下游的流动和传热进行了详细的实验研究，并与相同实验条件下圆孔的射流情形进行了比较，发现锥形喷口下游的速度边界层的等值线具有三种基本分布形态。随着锥形出口面积的增大，射流的穿透能力明显减弱，核心区域速度明显降低，侧向扩展范围明显增加，纵向耦合涡迅速减弱并消失，从而显著地提高了气膜冷却效率，尤其是提高了喷孔两侧流向下游位置上的冷却效率。同时，大锥顶角的高吹风比下，射流具有十分良好的贴壁效应和非常可观的冷却效率。

Abstract:

The paper reports on a detailed experimental study on flow and heat transfer in thedownstream of a cone-shaped film cooling hole with a mainstream. The jet hole with a cone-shapedapex angle of 15° or 30° was oriented so that its angle with respect to the test surface is 30°.Thelongitudinal velocity contours in the boundary layer at the downstream of cone-shaped exit have threebasic forms.Compared with circular jet,the ability of jet penetrating into mainstream and the velocityof jet cores were decreased obviously by increasinng area of jet exit, in the meantime, the lateralcovered region of jet becomes wider, and the strength of vortex is decreased. The cone-shaped holeappreciably increases the spreading of jet and decreases the strength of longitudinal vortex so that thefilm cooling effectiveness at positions laterally displaced from the centerlinne of the hole would bemuch greater than that found downstream of a circular hole. The shaped hole jet produces a successfulCoanda effect at the exit in the high blowing ratio and big cone apex angle so that it would results inhigh effectiveness.