对流槽宽高比对长方体湍流热对流系统传热的影响

摘要

This paper reports high-precision measurements of the Nusselt number Nu as a function of the Rayleigh number Ra, which in water-filled rectangular Rayleigh-B(e)nard (RB) convection cells of aspect ratio (Γx.Γy) =(1.00,0.30), (2.00,0.60), (4.00,1.20), (7.25,2.18), (14.29,4.29) and (20.84,6.25), over the Rayleigh number range 5. 0 × 105≤Ra≤5.6 × 1010 and the Prandtl number range 5. 3 ≤Pr≤7.0. The results show that, unlike the situation in the cylindrical cells, the turbulent heat transport in rectangular cells is nearly independent of the cells' aspect ratios.%采用长方体对流槽,研究以水为流体介质的Rayleigh-Bénard (RB)湍流热对流系统中,对流槽宽高比对系统湍流传热Nu-Ra关系的影响.改变对流槽的高度,使对流槽的宽高比分别为(Γx,Γy)=(1.00,0.30),(2.00,0.60),(4.00,1.20),(7.25,2.18),(14.29,4.29)和(20.84,6.25),实验参数Rayleigh数(Ra)和Prandtl数(Pr)的变化区间分别为5.0×105≤Ra≤5.6×1010和5.3≤Pr≤7.0.结果表明,与圆柱形对流槽中的情形不同,长方体对流槽中系统湍流传热的Nu-Ra关系几乎独立于系统对流槽的宽高比.