厚壁带肋通道换热性能及温度梯度场数值研究
首发时间:2019-06-18
摘要:采用耦合传热计算方法,研究了厚壁带肋通道内壁面温度梯度的分布规律及其与换热系数的相互关系,分析了厚壁通道固体域详细的温度梯度场,同时对比了蒸汽和空气冷却时通道最大温度梯度、平均温度梯度及平均换热系数随雷诺数的变化规律。研究结果表明:通道内壁面中心线上温度梯度和努塞尔数沿流向的分布呈现正相关关系;高的换热系数变化率是引起大温度梯度值的重要原因之一;最大温度梯度出现在内壁面靠近入口处,肋片处和壁面交接处也是温度梯度较高的区域;从内壁面到外壁面,温度梯度逐渐降低,分布也更加均匀;本研究工况下蒸汽冷却相比于空气冷却在提高换热效果的同时并没有引起更高的温度梯度,进而也不会带来更大的热应力问题。
关键词: 动力机械工程 带肋通道 换热性能 温度梯度 耦合计算
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Numerical Study on Heat Transfer Performance and Temperature Gradient Distributions of a Thick-wall Ribbed Channel
Abstract:Based on the conjugate calculation approach, the temperature gradient distributions for the inner walls of the thick-wall ribbed channel and its relation with the heat transfer coefficient were studied. The detailed temperature gradient distributions of the thick-wall channel solid domain was analyzed. The variation trends of the maximum temperature gradient, the average temperature gradient and the average heat transfer coefficient of the channel with Reynolds number were compared between steam cooling and air cooling. The results indicate that there is a positive correlation between the distributions of the temperature gradient and Nu on the centerline of the channel along the flow direction. The high heat transfer coefficient change rate is one of the important reasons for the large temperature gradient. The maximum temperature gradient appears at the entrance of channel on the inner wall, the temperature gradient values near the ribs and the wall junctions are also high. The temperature gradient gradually decreases and the distribution is more uniform from inner walls to outer walls of the thick-wall channel. The steam cooling could improve the heat transfer effect but do not cause a higher temperature gradient which could bring greater thermal stress, when compared with the air cooling.
Keywords: Power mechanical engineering ribbed channel heat transfer performance temperature gradient conjugate calculation
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