高压涡轮动叶叶尖非定常气热特性研究

Unsteady Investigation on Flow and Heat Transfer Characteristics of Turbine Blade Squealer Tip

本文针对高压涡轮动叶凹槽叶尖流动传热问题开展非定常数值模拟研究。结果表明,TBR模型Time Transformation方法适用于动叶叶尖非定常气热分析。压力侧泄漏流引起的卷吸涡在凹槽底部形成带状高换热系数区,机匣边界层流动使吸力侧肋顶靠近前缘区域形成局部高换热系数。随着叶尖凹槽深度增加,凹槽内流场低速区域扩大,卷吸涡尺寸也随之增大。相应地,凹槽底部的换热过程减弱,沿压力侧肋分布的带状高换热系数区域范围减小,其位置逐渐远离压力侧肋,并且在特定时刻呈现间断离散的分布特点。不同时刻,2%凹槽深度的叶尖中凹槽底部的平均换热系数相比3%凹槽深度的叶尖升高7.1%~13.5%,相比3.5%凹槽深度的叶尖升高9.6%~21.9%。

Unsteady flow and heat transfer characteristics on blade squealer tip of a high-pressure turbine was investigated by numerical simulation.Results indicate that Time Transformation method in TBR model is suitable for unsteady aerothermal analysis of turbine blade tip.The roll-up vortex caused by leakage flow from pressure side forms stripe distribution of high heat transfer coefficient at cavity floor,and boundary layer flow makes suction side squealer rim near leading edge form local high heat transfer coefficient.As cavity depth increases,flow field with low speed inside the cavity expands and the size of roll-up vortex also increases.Meanwhile,heat transfer at cavity floor weakens,the range of striped high heat transfer coefficient narrows down and its position gradually moves away from pressure side showing more discrete distribution characteristics at some instants.At different instants,average heat transfer coefficient at cavity floor of blade tip with 2%cavity depth was increased by 7.1%∼13.5%compared to tip with 3%cavity depth and was increased by 9.6%∼21.9%compared to tip with 3.5%cavity depth.