基于大涡模拟的空气绕流微细管流动特性研究

Study on The Flow Characteristics of Air Around Microtube Based on Large Eddy Simulation

在1000≤Re≤7000范围内,采用大涡模拟对空气绕流1mm微细管进行了数值研究,通过升阻力特性和时均雷诺应力分布等湍流统计特性着重研究微细管表面受力特性以及极近尾流区流动特性。结果表明,在获取空气绕流微细管湍流统计特性时,统计70个涡脱周期的时间足以获得可靠的时均统计结果;随着临界雷诺数的增大,时均阻力系数和微细管表面压差阻力变化趋势相同先减小后增大,表面摩擦阻力减小,流动分离提前;此外极近尾流区湍流脉动强度在雷诺数增大到5000后,继续增加雷诺数对极近尾流区湍流发展无明显促进作用。

In the range of 1000≤Re≤7000,large eddy simulations are used to study the air flow around the 1 mm microtube,and the turbulence statistical characteristics such as the lift-up resistance characteristics and the time-averaged Reynolds stress distribution are used to study the surface force characteristics of the microtubes and the flow characteristics in the extremely close wake region.The results show that when obtaining the statistical characteristics of the turbulence flow of the air around the microtube,the time of 70 cycles is enough to obtain reliable time-averaged statistical results.With the increase of the critical Reynolds number,the change trend of the average drag coefficient and the differential pressure resistance on the surface of the microtube is the same,which decreases first and then increases,the surface friction resistance decreases,and the flow separation advances.In addition,after the increase of the Reynolds number to 5000,the turbulent pulsation intensity in the near-wake region has no obvious effect on the development of turbulence in the near-wake region.