百叶式风窗流场分布及局部阻力特征研究

Study on flow field distribution and local resistance characteristics of louvered windshield

为确定百叶式风窗的流场分布特征,叶片角度和有效过风面积与局部阻力系数的关系,采用CFD数值模拟的方法,对叶片开启不同角度下,风窗局部流场特征进行三维仿真研究。研究结果表明:叶片开启45°后导致局部阻力突变和风流重新分配;主流风速在风窗入口逐渐形成,随距底板高度的增加,高风速区域面积不断增加,风速峰值随风流向风窗后方移动;风窗前0.5 m区域局部阻力逐渐减小,风窗区域局部阻力先增大后减小;局部阻力做功所带来的能量损失,导致流场分布特征发生改变,在增速减压区和减速增压区与边壁的闭合区域形成上下涡流区,同时通过非线性拟合得到风窗局部阻力系数与叶片开启角度成幂函数关系。

In order to determine the flow field distribution characteristics of the louvered windshield and the relationship between the blade angle,the effective wind area and the local resistance coefficient,the CFD numerical simulation method was used to carry out the three-dimensional simulation on the local flow field characteristics of the windshield under different opening angles of blades.The results showed that after the blades were opened as 45°,the local resistance changed suddenly and the wind flow redistributed.The mainstream wind speed gradually formed at the entrance of windshield,and with the increase of the height from bottom plate,the area of the high wind speed region increased continually,and the peak wind speed moved to the rear of windshield with the wind flow.The local resistance in the region with 0.5 m in front of windshield gradually decreased,and the local resistance in the windshield region increased first and then decreased.The energy loss caused by the work done by the local resistance led to the change in the distribution characteristics of flow field,and the upper and lower vortex regions were formed in the closed regions of acceleration decompression region and deceleration pressurization region with the side wall.At the same time,the power function relationship between the local resistance coefficient of windshield and the opening angle of blades was obtained through the nonlinear fitting.