雷诺数对圆柱气动力和流场影响的试验研究

Experimental study on Reynolds number effect on aerodynamic pressure and forces of cylinder

通过刚性模型测压风洞试验,研究了圆柱的气动阻力、气动升力系数和风压系数随雷诺数的变化规律,从流场分布的角度分析了气动力变化的原因,并研究了雷诺数影响下的流场在圆柱轴向的相关性。结果表明:在亚临界雷诺数区域,在时间平均上流场沿模型两侧呈对称分布,雷诺数对平均阻力系数和流场影响较小,平均升力系数基本为零。在临界雷诺数区域,随着特定区域大负压区的出现,流场不再对称,出现不容忽视的平均升力和脉动升力。在超临界雷诺数区域,随着对称侧大负压区的出现,流场恢复对称状态,平均升力基本消失。雷诺数对流场的轴向相关性有显著的影响。在雷诺数较低时(亚临界区域),卡门涡在轴向上的尺度相对较大,而随着雷诺数的提高,该尺度逐渐减小,各断面流场的相关性降低。

By wind tunnel tests,Reynolds number effect on drag force coefficient,lift force coefficient and wind pressure coefficient of cylinder were measured,the mechanism of the aerodynamic force variation from the point of view of the flow field distribution was analyzed,and the correlation of the flow field in the cylinder axis direction under the Reynolds number effect was studied. Results show that in the subcritical Reynolds number regime,the time averaged flow field around the cylinder model is symmetric,the Reynolds number has little influence on the averaged drag force coefficient and flow field,and the averaged lift force is around zero. In the critical Reynolds number regime,with the appearance of large amplitude negative pressure in certain areas,flow field becomes asymmetric,and the averaged lift force as well as fluctuation lift force appears. In the supercritical Reynolds number regime,with the appearance of large amplitude negative pressure on the two sides,flow field becomes to symmetric again,and the averaged lift force disappears. Reynolds number has obvious effect on the flow field correlation along the cylinder axis. In the subcritical Reynolds number regime,the scale of the Karman vortex in the cylinder axis direction is relatively large,while the scale becomes small with the increase of Reynolds number.