Supervised by: China Aerospace Science and Technology Corporation
Sponsored by: China Academy of Aerospace Aerodynamics
Chinese Society of Astronautics
China Aerospace Publishing House Co., LTD
WANG Mu, CHEN Yang, WANG Wei, et al. Experiment for Heat Transport and Flow Structure of a Two-Layer Thermal Convection[J]. PHYSICS OF GASES. DOI: 10.19527/j.cnki.2096-1642.1066
Citation: WANG Mu, CHEN Yang, WANG Wei, et al. Experiment for Heat Transport and Flow Structure of a Two-Layer Thermal Convection[J]. PHYSICS OF GASES. DOI: 10.19527/j.cnki.2096-1642.1066

Experiment for Heat Transport and Flow Structure of a Two-Layer Thermal Convection

  • Two-layer thermal convection exists widely in nature. In the present work, an experiment was conducted to inves- tigate the heat transport and flow structure in two-layer thermal convection. In a rectangular convection cell, two immiscible fluids, glycerol and 2 cs silicone oil, were used as the working fluids. In the lower-thin glycerol layer, the bottom boundary was subjected to a no-slip boundary condition (BC), and the interface was subjected to slip BC. The aspect ratio of glycerol layer (lower) was Γ1=10.4. The Rayleigh number and Prandtl number of the glycerol layer covered the ranges of 260 ≤ Ra1 ≤ 6 000 and 3 708<Pr1<7 000, respectively. In the upper-thick silicone oil layer, the boundary at the top was subjected to no-slip BC. The aspect ratio of silicone oil (upper) was Γ2=0.53. The Rayleigh number and Prandtl number of the silicone oil layer covered the ranges of 1.5×109Ra2 ≤ 2.0×1010 and 28<Pr2 <33. It is found that the two-layer thermal convection has different heat transfer efficiencies and flow structures in two regions. For region 1 where the heat flux is smaller than a certain value, the glycerol layer (lower) is in a stable stratified state. For region 2 where the heat flux is greater than the certain value, a cellular pattern was formed in glycerol layer and the global heat transport was sharply increased through a subcritical bifurcation. The heat transport of glycerol layer exhibits oscillatory instability at the critical Rayleigh number Ra1c=1 523, which is smaller than the theoretic value 1 708 of critical value Ra for the 2D infinite Rayleigh-Bénard convection (RBC) with both rigid BCs. It reveals that the slip BC makes the fluid become unstable easier and enhances the heat transport. A measurement with shadowgraph method was further conducted. The cellular pattern of glycerol layer, the interface and hot plumes were also studied.
  • loading

Catalog

    /

    DownLoad:  Full-Size Img  PowerPoint
    Return
    Return