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首页> 外文会议>The 2001 ASME International Mechanical Engineering Congress and Exposition, 2001, Nov 11-16, 2001, New York, New York >EXPERIMENTAL INVESTIGATION OF LOCAL HEAT TRANSFER DISTRIBUTION ON SMOOTH AND ROUGHENED SURFACES UNDER AN ARRAY OF ANGLED IMPINGING JETS
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EXPERIMENTAL INVESTIGATION OF LOCAL HEAT TRANSFER DISTRIBUTION ON SMOOTH AND ROUGHENED SURFACES UNDER AN ARRAY OF ANGLED IMPINGING JETS

机译：倾斜撞击射流阵列中光滑和粗糙表面上局部传热分布的实验研究

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摘要

Measurements of the local heat transfer distribution on smooth and roughened surfaces under an array of angled impinging jets are presented. The test rig is designed to simulate impingement with cross-flow in one direction which is a common method for cooling gas turbine components such as the combustion liner. Jet angle is varied between 30, 60, and 90 degrees as measured from the impingement surface, which is either smooth or randomly roughened. Liquid crystal video thermography is used to capture surface temperature data at five different jet Reynolds numbers ranging between 15,000 and 35,000. The effect of jet angle, Reynolds number, gap, and surface roughness on heat transfer efficiency and pressure loss is determined along with the various interactions among these parameters. Peak heat transfer coefficients for the range of Reynolds number from 15,000 to 35,000 are highest for orthogonal jets impinging on roughened surface; peak Nu values for this configuration ranged from 88 to 165 depending on Reynolds number. The ratio of peak to average Nu is lowest for 30-degree jets impinging on roughened surfaces. It is often desirable to minimize this ratio in order to decrease thermal gradients, which could lead to thermal fatigue. High thermal stress can significantly reduce the useful life of engineering components and machinery. Peak heat transfer coefficients decay in the cross-flow direction by close to 24% over a dimensionless length of 20. The decrease of spanwise average Nu in the crossflow direction is lowest for the case of 30-degree jets impinging on a roughened surface where the decrease was less than 3%. The decrease is greatest for 30-degree jet impingement on a smooth surface where the stagnation point Nu decreased by more than 23% for some Reynolds numbers.
机译：提出了在一系列成角度的撞击射流下在光滑和粗糙表面上的局部传热分布的测量值。该试验台被设计为模拟一个方向上的横流冲击，这是冷却燃气轮机部件（如燃烧室衬套）的常用方法。从撞击表面测得的喷射角度在30度，60度和90度之间变化，该角度可以是光滑的，也可以是随机粗糙的。液晶视频热像仪用于捕获55,000至35,000之间的五个不同雷诺数的表面温度数据。确定了喷射角，雷诺数，间隙和表面粗糙度对传热效率和压力损失的影响以及这些参数之间的各种相互作用。雷诺数范围从15,000到35,000的峰值传热系数对于撞击粗糙表面的正交射流最高。此配置的最大Nu值范围在88到165之间，具体取决于雷诺数。对于撞击在粗糙表面上的30度射流，峰值与平均Nu的比率最低。通常希望最小化该比率以减小可能导致热疲劳的热梯度。高的热应力会大大缩短工程部件和机械的使用寿命。在无量纲长度为20的情况下，峰值传热系数在横流方向上衰减近24％。对于30度射流撞击在粗糙表面上的情况，在横流方向上翼展方向平均Nu的减小最低。下降幅度小于3％。对于在光滑表面上的30度射流撞击，该减小最大，对于某些雷诺数，该点的停滞点Nu减小了23％以上。

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