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首页> 外文期刊>International Journal of Heat and Mass Transfer >Chaotic natural convection in a toroidal thermosyphon with heat flux boundaries
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Chaotic natural convection in a toroidal thermosyphon with heat flux boundaries

机译：具有热通量边界的环形热虹吸管中的混沌自然对流

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摘要

This computational study investigates nonlinear dynamics of unstable convection in a 3D toroidal shaped thermal convection loop (i.e., thermosyphon) with heat flux boundary conditions; results are compared to prior 2D simulations. The lower half of the thermosyphon is subjected to a positive heat flux into the system while the upper half is cooled by an equal-but-opposite heat flux out of the system. Water is employed as the working fluid with fully temperature dependent thermophysical properties and the system of governing equations is solved using a finite volume method. Numerical simulations are performed for varying magnitudes of heat flux (1.0 W/m~2 ≤ q" ≤ 1.0 × 10~4 W/m~2) to yield Rayleigh numbers (i.e., buoyant forcing) ranging from 2.83 × 10~4 ≤ Ra ≤ 2.83 × 10~8. Delineation of multiple convective flow regimes is achieved through evolution of the bulk-mass-flow time-series and the trajectory of the mass flow attractor. Simulation results demonstrate that multiple regimes are possible and include: (1) conduction, (2) damped, stable convection that asymptotes to steady-state, (3) unstable, Lorenz-like chaotic convection with flow reversals, and (4) high Rayleigh, aperiodic stable convection without flow reversals. For the Rayleigh numbers considered, it is observed that certain flow regimes are not accessible in toroidal simulations owing to the constraints of additional surface boundaries in a 3D system. The RMS of mass flow rate, power spectra of oscillatory behavior, dominant oscillatory frequency, and residence time are also described as a function of the buoyant forcing in the system.
机译：这项计算研究研究了具有热通量边界条件的3D环形热对流回路（即热虹吸管）中不稳定对流的非线性动力学;将结果与先前的2D模拟进行比较。热虹吸管的下半部分受到进入系统的正热通量，而上半部分被相等但相反的热通量冷却出系统。将水用作具有完全取决于温度的热物理性质的工作流体，并且使用有限体积法求解控制方程组。对不同的热通量（1.0 W / m〜2≤q“≤1.0×10〜4 W / m〜2）进行数值模拟，以得出2.83×10〜4≤的瑞利数（即浮力） Ra≤2.83×10〜8。通过体质流时间序列的演化和质流吸引子的轨迹来描述多种对流形式，模拟结果表明多种形式是可行的，包括：（1 ）传导；（2）渐近稳定的阻尼稳定对流；（3）具有逆流的不稳定，类似于Lorenz的混沌对流；以及（4）高瑞利，非逆流的非周期性稳定对流，考虑了瑞利数，观察到由于3D系统中附加的表面边界的限制，在环形模拟中无法访问某些流态，还描述了质量流率RMS，振荡行为的功率谱，主要振荡频率和停留时间。很好玩系统中浮力的作用。

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  • 作者

    W.F. Louisos; D.L. Hitt; C.L. Danforth;

  • 作者单位

    College of Engineering and Mathematical Sciences, The University of Vermont, United States,Mechanical Engineering Program, School of Engineering, The University of Vermont, Votey Building, 33 Colchester Avenue, Burlington, VT 05405, United States;

    College of Engineering and Mathematical Sciences, The University of Vermont, United States,Mechanical Engineering Program, School of Engineering, The University of Vermont, Votey Building, 33 Colchester Avenue, Burlington, VT 05405, United States;

    College of Engineering and Mathematical Sciences, The University of Vermont, United States,Department of Mathematics & Statistics, The University of Vermont, 16 Colchester Avenue, Burlington, VT 05401, United States,Vermont Complex Systems Center, Vermont Advanced Computing Core, The University of Vermont, Farrell Hall 210 Colchester Avenue, Burlington, VT 05405, United States;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Thermosyphon; Toroidal thermosyphon; Natural convection; Unstable convection; Lorenz-like chaos; Rayleigh number (Ra);

    机译：热虹吸管;环形热虹吸管;自然对流;对流不稳定;洛伦兹式的混乱;瑞利数（Ra）;

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