定热流下振荡流动对对流换热的影响

对定热流下平行板间振荡层流的对流换热过程进行了解析分析。流动的振荡过程是通过压力梯度上的振荡分量来完成的。对流动过程作了一些简化假设，并着重讨论振荡频率、雷诺数、振幅等参数对对流换热的影响。结果表明，振荡使对流换热系数增加。

ApplicationOriented Study of the Effect of Pulsating Flow on Convective Heat Transfer for Uniform Heat Flux

In trying to apply Rijke tube to energy saving in Zhejiang province, we found it necessary to supplement our understanding of its mechanism. Zhejiang province has kindly funded our project on such mechanism. We now present part of our research progress on this project. Instead of the actual Rijke tube, we took two infinite flat plates as a crude model to begin with. The gap between the plates or walls was 2a; thus distance of wall from mid plane was a. The walls were assumed to be under uniform heat flux. For such a model, we took from Ref. two equations, eqs.(8a) and (8b) in our paper. For the same model, we also derived eqs.(E) and (F) in the appendix of our paper. These four equations were used in our numerical calculations. Fig.1 shows the variation of u t/u sa (dimensionless pulsating velocity) with distance from mid plane for different phase angles of pulsation. Fig.1a is for M =0.1, r =0.5 and Fig.1b is for M =10 and r =0.5, where M is dimensionless pulsating frequency, r is the pulsating amplitude of pressure gradient. When M increases from 0.1 to 10, u t/u sa is greatly reduced and the u t/u sa vs y/a curves become highly distorted. Fig.4 shows the variation of wall temperature with M .In Fig.4, the temperature is large for small M below M =0.5. Fig.5 shows the variations of h p (heat transfer coefficient for pulsating flow) and h s (heat transfer coefficient for steady flow) with time. Fig.5 shows that h p is much larger than h s . From our numerical analysis, we arrive at the following important conclusion: that convective heat transfer coefficient is much higher in pulsating flow as compared with steady flow is due to the nonlinear coupling of velocity field with temperature field.