重力场下平板边界层内气液两相流动数值分析

通气减阻技术因具有降低能耗和环境污染小等效果,在工程领域内得到广泛关注。为研究重力场中气相在平板湍流边界层内流动演化过程及由此产生的减阻效应,该文耦合连续表面张力(CSF)的VOF多相流模型和标准k-?湍流模型,求解非定常RANS方程,对边界层内气液两相流动进行数值模拟。通过计算结果与实验结果的对比,验证了数值方法的有效性;进而对不同通气流量和来流雷诺数下,气泡当量直径、近壁区空隙率及流动减阻率进行定量分析。结果表明:减阻效应与近壁区空隙率密切相关;来流雷诺数和通气量的提高,均能增强减阻效应。

Numerical simulation of gas-liquid two-phase flow in flat plate boundary layer under gravity field

The technology of ventilated drag reduction which can reduce energy consumption and environmental pollution gets widespread attention.In order to study on the evolution of ventilated flow and the resultant performance of drag reduction in flat plate boundary layer,the finite volume element method based on VOF model coupled with continuous surface force and standard k-ε turbulence model is adopted to solve unsteady RANS equations in this paper.The credibility of the proposed numerical method is verified by comparing the numerical results with the experimental data.Then,a series of simulations are calculated to analyze the bubble size,near-wall mean void fraction,and performance of drag reduction quantificationally under different Reynold numbers and ventilated flux.The numerical results show that the performance of drag reduction is closely related to the near-wall mean void fraction.And the performance of drag reduction increases with higher Reynold number and ventilated flux.