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首页> 外文期刊>International Journal of Heat and Mass Transfer >Effect of oscillatory motion on heat transfer at vertical flat surfaces
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Effect of oscillatory motion on heat transfer at vertical flat surfaces

机译：振荡运动对垂直平面传热的影响

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摘要

The effect of oscillations on heat transfer at vertical surfaces is investigated and a model is developed that predicted both the transient and time average heat transfer rates. The transient behavior of the heat transfer indicates the presence of an oscillatory component superimposed on a larger steady one that does not reach zero during flow reversal. This was explained in terms of the interaction between a "quasi-steady oscillatory" mechanism near the leading edge, and a "pseudo-steady diffusive" far from it. The analysis further revealed that the time average heat transfer rate can be adequately estimated using a mixed "forced-natural" convections correlation, with the forced convection component estimated based on the time average oscillatory Reynolds number Re_v ＝ αwL/v. The agreement between the model predictions and the experimental measurements makes it applicable for predicting heat transfer characteristics and velocity fluctuations near heated vertical surfaces in presence of oscillatory motion. The model is also applicable for predicting heat transfer rates under conditions where oscillatory motion is used to achieve specificity in temperature control without affecting process residence time, such as in biomedical and biochemical applications. The modest heat transfer enhancement (< 2) due to oscillatory motion is attributed to the small convective term in the energy equation, which is consistent with previous investigations where increasing the axial temperature gradient in presence of oscillatory motion was shown to achieve much higher heat transfer enhancement.
机译：研究了振荡对垂直表面传热的影响，并建立了一个模型，该模型可预测瞬时和时间平均传热速率。传热的瞬态行为表明存在一个振荡分量，该振荡分量叠加在一个较大的稳定分量上，该流动分量在逆流过程中不会达到零。这是根据前沿附近的“准稳态振荡”机制和远离前沿的“伪稳态扩散”机制之间的相互作用来解释的。分析进一步表明，可以使用混合的“自然对流”对流相关性充分估计时间平均传热速率，并且基于时间平均振荡雷诺数Re_v ＝αwL/ v估算强迫对流分量。模型预测与实验测量值之间的一致性使其可用于预测在存在振荡运动的情况下，加热的垂直表面附近的传热特性和速度波动。该模型还适用于在诸如生物医学和生化应用中使用振荡运动实现温度控制特异性而不影响过程停留时间的条件下预测传热速率。振动引起的适度传热增强（<2）归因于能量方程中的小对流项，这与以前的研究一致，在先前的研究中，在存在振动的情况下增加轴向温度梯度可实现更高的传热增强。

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