钝头型市域列车尾流吸气主动控制减阻研究

Study on drag reduction of blunt subway trains wake suction active control

为探究钝头外形的市域列车运行时尾部吸气控制对列车气动阻力的影响,缓解列车因提速造成的阻力增加问题,采用Realizable k-ε两方程模型的DDES数值仿真方法开展研究,通过风洞试验验证数值模拟方法后,以数值仿真得到的速度场、压力场及各节车的气动阻力分布及组成,分析吸气控制对钝头型市域尾车气动减阻的影响原因。研究结果表明:钝头型市域列车的尾车流线型表面由负压强主导,因此压差阻力占比较大,并且空气绕该部位流动时形成了2个比较明显且对称的流动分离泡,导致了尾车阻力系数尤其是压差阻力系数急剧增大,使尾车压差阻力比重最大,占整车阻力的36.71%;在列车尾部进行吸气控制能提升列车尾部中心区的压力,使尾车的压差阻力显著减小,进而实现整车减阻;在不同吸气方案下,尾车减阻率随着吸气面的增加而增加,当设置的所有吸气面工作时,对尾车的气动减阻率最高可达21.6%;列车离吸气面越远的部位减阻效果越不明显,位于尾部吸气控制上游较远的头车最大减阻率仅为1%,而中间车的减阻率为4%;随着吸气速度从0.2U提升至0.6U,尾车减阻率从17.9%提升至21.6%,整车减阻率从8.3%提升至10.3%,尾车流线型区域后方的正压区也越接近尾车流线型表面。研究结果可为钝头型市域列车主动控制的气动减阻提供参考。

To investigate the impact of tail suction control during the operation of blunt-nosed urban trains on the aerodynamic drag of the train,and to alleviate the problem of increased resistance caused by acceleration,the DDES numerical simulation method of the Realizable k-εtwo-equation model was adopted in this paper.After verifying the numerical simulation method through wind tunnel experiments,the velocity field,pressure field,and the distribution and composition of aerodynamic drag of each car obtained from the numerical simulation were used to analyze the reasons for the influence of suction control on the aerodynamic drag reduction of the blunt-nosed urban tail car.The research results show that the streamline surface of the tail car of the blunt-nosed urban train is dominated by negative pressure,so the pressure difference resistance accounts for a large proportion.Moreover,when the air flows around this part,two relatively pronounced and symmetrical flow separation bubbles are formed,leading to a sharp increase in the tail car resistance coefficient,especially the pressure difference resistance coefficient,making the tail car pressure difference resistance the largest,accounting for 36.71%of the total car resistance.Performing suction control at the tail of the train can increase the pressure in the central area of the tail,significantly reducing the pressure difference resistance of the tail car and thus achieving overall car drag reduction.Under different suction schemes,the tail car drag reduction rate increases with increasing suction surface.When all the set suction surfaces are working,the maximum aerodynamic drag reduction rate for the tail car can reach 21.6%.The further the part of the train is from the suction surface,the less obvious the drag reduction effect.The maximum drag reduction rate of the head car,which is far upstream from the tail suction control,is only 1%,while the middle car’s drag reduction rate is 4%.As the suction speed increases from 0.2U to 0.6U,the tail car drag reduction rate increases from 17.9%to 21.6%,the overall car drag reduction rate increases from 8.3%to 10.3%,and the positive pressure area behind the tail car streamline area is closer to the tail car streamline surface.The research results provide a reference for the active aerodynamic drag reduction control of blunt-nosed urban trains.