Forced convection heat transfer enhancement using a self-oscillating impinging planar jet
Forced convection heat transfer enhancement using a self-oscillating impinging planar jet
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DOI：
10.1115/1.1471521
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发表时间：
2002-08-01
影响因子：
--
通讯作者：
Herr, F
中科院分区：
文献类型：
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作者：
Camci, C;Herr, F
冲击射流广泛应用于燃气涡轮机叶片内部通道的局部换热强化。静止射流阵列通常冲击内部冷却通道的表面。目前的做法是受益于存在于目标壁上的射流冲击区域附近的高传热系数。本研究表明，自振荡冲击射流配置是非常有益的，在提高传统的（固定）冲击射流的散热性能。由于振荡冷却剂射流的固有扫掠运动，除了高度升高的滞止线Nusselt数之外，冲击区的面积覆盖率显著增强。当振荡射流（Re=14，000）冲击垂直于射流轴线的平板（x/d=24孔到平板的距离）时，驻点线上的Nu数典型的增加约为70%。本文通过对交叉热线信号的三重分解，详细地解释了自激振荡射流的流体动力学结构。目前的传热增强水平表明，有可能在未来的燃气涡轮机冷却系统、旋转盘、玻璃回火/淬火、电子设备冷却、飞机除冰、燃烧室和热交换器中实施本发明的自振荡冲击射流概念。
Impinging jets are widely used in the local enhancement of heat removed from internal passages of gas turbine blades. Arrays of stationary jets are usually impinged on surfaces of internal cooling passages. The current practice is to benefit from the high heat transfer coefficients existing in the vicinity of the jet impingement region on a target wall. The present study shows that a self-oscillating impinging-jet configuration is extremely beneficial in enhancing the heat removal performance of a conventional (stationary) impinging jet. In addition to a highly elevated stagnation line Nusselt number the area coverage of the impingement zone is significantly enhanced because of the inherent sweeping motion of the oscillating coolant jet. When an oscillating jet (Re=14, 000) is impinged on a plate normal to the jet axis (x/d=24 hole to plate distance), a typical enhancement of Nu number on the stagnation line is about 70 percent. The present paper explains detailed fluid dynamics structure of the self-oscillating jet by using a triple decomposition technique on a crossed hot wire signal. The current heat transfer enhancement levels achieved suggest that it may be possible to implement the present self-oscillating-impinging-jet concept in future gas turbine cooling systems, on rotating disks, glass tempering/quenching, electronic equipment cooling, aircraft de-icing, combustors and heat exchangers.