The Effects of Ribs and Tip Wall Distance on Heat Transfer for a Varying Aspect Ratio Two-Pass Ribbe
The Effects of Ribs and Tip Wall Distance on Heat Transfer for a Varying Aspect Ratio Two-Pass Ribbe
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DOI：
10.1115/1.4006584
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发表时间：
2013-03
影响因子：
1.7
通讯作者：
I. V. Shevchuk
中科院分区：
文献类型：
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作者：
I. V. Shevchuk
由于叶片从前缘到后缘的厚度不同，因此在燃气涡轮叶片中通常会发现具有不同长宽比的内部冷却通道。这些蛇形通道通常包含多个 180 度的弯曲，这些弯曲在叶片尖端区域具有锋利的边缘。 180 度弯曲对出口通道和尖端壁中的传热特性具有显着影响，其中由于弯曲中的分隔壁到尖端壁的距离，可以看到强烈的影响。本研究研究了分隔壁到尖端壁距离对于具有 2:1 入口和 1:1 出口通道的带肋双通道冷却通道的影响。使用瞬态热致变色液晶技术进行空间分辨传热测量，以实现使用平行 45 度肋的平滑肋结构。分别确定了 180 度弯曲对传热和肋引起的增强的影响，并发现弯曲效应主导弯曲附近出口通道的传热增加。还针对一系列尖端壁距离独立评估了由于弯曲和肋导致的压力损失。结果表明，较小的尖端壁距离增加了尖端壁和出口通道上的传热，但代价是增加了压力损失。建议采用最佳的尖端壁位置，在改善传热和增加压力损失之间形成折衷。
Internal cooling channels with differing aspect ratios are typically found in gas turbine blades due to the varying thickness of the blade from the leading to trailing edge. These serpentine passages often contain several 180 deg bends, which are sharp edged in the region of the blade tip. The 180 deg bend has a pronounced effect on the heat transfer characteristics in the outlet channel and tip wall, where a strong influence is seen due to the divider wall-to-tip wall distance in the bend. The present study investigates the effect of the divider wall-to-tip wall distance for a ribbed two-pass cooling channel with a 2:1 inlet and 1:1 outlet channel. Spatially resolved heat transfer measurements were made using the transient thermochromic liquid crystal technique for a smooth and a ribbed configuration using parallel 45 deg ribs. Effects of the 180 deg bend on heat transfer and rib-induced enhancements were identified separately and bend effects were found to dominate the heat transfer increase in the outlet channel near the bend. Pressure losses due to the bend and ribs were also independently evaluated for a range of tip wall distances. Results show that the smaller tip wall distances increase heat transfer on the tip wall and outlet channel but at the cost of an increased pressure loss. An optimum tip wall position is suggested, forming a compromise between heat transfer improvement and increased pressure losses.