论文标题
混合对流流中自由振动的圆柱的流体动力和热特性
Hydrodynamic and thermal characteristics of a freely-vibrating circular cylinder in mixed convection flow
论文作者
论文摘要
混合对流流中自由振动的圆柱体的流体动力和热特性在低雷诺数下进行了数值研究。对一系列参数进行了数值研究，UR = [2.0，10]，PR = [0.7，10]和RI = [0.5，2.0]。而雷诺的数字，质量比和阻尼比是固定的。在高降低速度值的高理查森号RI = 2.0的情况下，发现了次级VIV锁定区域，其中浮力驱动的流量是非平淡的。形成一个宽阔的体内锁定区域，在流体和结构之间具有巨大的能量转移，这对于水力发电非常有意义。详细讨论了PrandTL和Richardson数量对流体动力学，结构动力学和传热的影响。对于高prandtl数量的情况，温度轮廓集中在圆柱周围，这与高平均努塞尔特值有关。通过计算平均努塞尔特数量及其在不同情况下的波动来量化对圆柱体表面传热效率的影响。使用混合对流流中的流体和结构之间的能量转移。圆柱体的横向位移与升力力之间的相角差用于支持能量转移的讨论。得出了任意拉格朗日 - 欧拉语描述中稳定的有限元公式。在各种环境中，有记录了结构动力学和涡旋诱导的振动，例如不同的速度，prandtl数字和理查森数量。还记录并讨论了结构动力学对加热圆柱体传热效率的影响。获得的数值结果与文献和已建立的经验公式非常匹配。
The hydrodynamic and thermal characteristics of a freely-vibrating circular cylinder in mixed convection flow are numerically investigated at low Reynolds numbers. The numerical investigations are conducted for a range of parameters, Ur = [2.0, 10], Pr = [0.7, 10] and Ri = [0.5, 2.0]. Whereas the Reynolds number, the mass ratio and the damping ratio are fixed. A secondary VIV lock-in region is found in the cases of high Richardson number Ri=2.0 for high reduced velocity values, in which the buoyancy-driven flow is non-trivial. A wide VIV lock-in region is formed with tremendous energy transfer between fluid and structure, which is extremely meaningful for hydropower harvesting. The influences of Prandtl and Richardson numbers on the hydrodynamics, structural dynamics and heat transfer are discussed in detail. The temperature contours are concentrated around cylinder for the cases of high Prandtl number, which are associated with high mean Nusselt values. The influence on heat transfer efficiency over the cylinder's surface is quantified via the calculation of mean Nusselt number and its fluctuation for different circumstances. The energy transfer coefficient is employed to quantify the energy transfer between fluid and structure in mixed convection flow. The phase angle difference between the transverse displacement of cylinder and the lift force is used to support the discussions of energy transfer. A stabilized finite element formulation in Arbitrary Lagrangian-Eulerian description is derived. The structural dynamics and vortex-induced vibration are documented for various environments, e.g., different reduced velocity, Prandtl numbers and Richardson numbers. The influence of structural dynamics on the heat transfer efficiency over a heated cylinder is recorded and discussed as well. The obtained numerical results match well with literature and the established empirical formula.
