带前缘涡轮动叶内冷通道流动换热数值模拟

在静止条件下,通过数值模拟的方法对接近真实的带前缘涡轮工作叶片腔模型内的流动与换热进行了分析.结果表明:腔内斜肋引发的三维涡对换热产生了巨大的影响,在一倍肋高范围内, Y-Z 和 X-Y 平面上都出现了肋后涡,使得此处传热系数降低;在 X-Z 平面上,第2通道产生一对方向相反的涡,第3通道只产生一个涡.两个通道中的涡都占据整个横截面,这些涡增加了通道流阻.冲击和气膜流动主导了前缘通道内的换热,冲击产生的一对涡加强了流动掺混,促进了前缘吸、压力面上的换热,而高速的气膜出流推动了这一过程.相同流量工况下,第2通道带肋表面的平均换热和局部换热都是最好的,而光滑的第1通道总压降最小,综合换热性能在各个通道中最高.随着雷诺数的增加,各通道吸、压力面的局部换热和平均换热都增强,但压降系数变化不大.

Numerical simulation of flow and heat transfer in internal cooling blade channel with leading-edge

Flow and heat transfer in approximate real model of blade channel with leading-edge was analyzed by numerical simulation at static condition.The results show:three-dimensional vortices introduced by inclined ribs lead to a great impact on heat transfer in the cavity.Within one rib height range,vortices after ribs occur in both Y-Z and X-Y cross-sections,which makes heat transfer coefficients here in decrease.In X-Z cross-section,the second channel produces a pair of vortices in the opposite direction while the third channel results in just one vortex.Vortices in these two channels occupy the whole cross-section and increase flow resistance.The impingement and film flow play a leading role in heat transfer in leading-edge channel where vortex pair induced by impingement enhances flow mixing and stimulates heat transfer on suction and pressure sides,while high-speed film flow promotes this process.In the same flow conditions,average and local heat transfer on ribbed surface of the second channel perform the best,but the smooth first channel owns the highest comprehensive heat transfer performance due to its minimum total pressure drop in all the channels.With the increasing Reynolds number,local and average heat transfer on suction and pressure sides in each channel are enhanced in contrast with little change in the pressure drop coefficient.