In this work,the flow surrounding the train was obtained using a detached eddy simulation(DES)for slipstream analysis.Two different streamlined nose lengths were investigated:a short nose(4 m)and a long nose(9 m).The ...In this work,the flow surrounding the train was obtained using a detached eddy simulation(DES)for slipstream analysis.Two different streamlined nose lengths were investigated:a short nose(4 m)and a long nose(9 m).The time-average slipstream velocity and the time-average slipstream pressure along the car bodies were compared and explained in detail.In addition to the time-averaged values,the _(max)imum velocities and the pressure peak-to-peak values around the two trains were analyzed.The result showed that the nose length affected the slipstream velocity along the entire train length at the lower and upper regions of the side of the train.However,no significant effect was recognized at the middle height of the train along its length,except in the nose region.Moreover,within the train’s side regions(y=2.0-2.5 m and z=2-4 m)and(y=2.5-3.5 m and z=0.2-0.7 m),the ratio of slipstream velocity U_(max) between the short and long nose trains was notably higher.This occurrence also manifested at the train’s upper section,specifically where y=0-2.5 m and z=4.2-5.0 m.Similarly,regarding the ratio of _(max)imum pressure peak-to-peak values Cp-p_(max),significant regions were observed at the train’s side(y=1.8-2.6 m and z=1-4 m)and above the train(y=0-2 m and z=3.9-4.8 m).展开更多
为了快速、准确分析螺旋桨滑流对增升装置的影响,采用实桨非定常方法(full blades method,FBM)和定常动量激励盘方法(actuator disk method,ADM),数值计算分析了前进比J=0.7、1.0,攻角α=–4°~24°工况下螺旋桨滑流对高升力构...为了快速、准确分析螺旋桨滑流对增升装置的影响,采用实桨非定常方法(full blades method,FBM)和定常动量激励盘方法(actuator disk method,ADM),数值计算分析了前进比J=0.7、1.0,攻角α=–4°~24°工况下螺旋桨滑流对高升力构型的影响。研究表明:虽然从单独螺旋桨获取的时均化激励盘载荷分布与从高升力构型螺旋桨获取的存在局部差异,但将来源不同的激励盘载荷应用于ADM计算时,所得高升力构型的压力分布、升阻力结果基本一致,全机升力系数差异不超过4.3%,阻力系数偏差小于5.4%,说明采用单独螺旋桨获取激励盘载荷对全机气动力计算影响不大,从而避免了复杂的网格生成。ADM将非定常计算转化为定常计算,在保持网格量相当(3300万)的条件下,其计算结果与FBM结果在失速前(α<20°时)基本吻合,同时计算核时约降低至FBM的1/18(170/3100)。因此ADM方法能够高效、合理评估出螺旋桨滑流对增升装置产生的影响。展开更多
基金Project(52202426)supported by the National Natural Science Foundation of ChinaProjects(15205723,15226424)supported by the Research Grants Council of the Hong Kong Special Administrative Region(SAR),China+1 种基金Project(K2021J041)supported by the Technology Research and Development Program of China RailwayProject(1-BD23)supported by The Hong Kong Polytechnic University,China。
文摘In this work,the flow surrounding the train was obtained using a detached eddy simulation(DES)for slipstream analysis.Two different streamlined nose lengths were investigated:a short nose(4 m)and a long nose(9 m).The time-average slipstream velocity and the time-average slipstream pressure along the car bodies were compared and explained in detail.In addition to the time-averaged values,the _(max)imum velocities and the pressure peak-to-peak values around the two trains were analyzed.The result showed that the nose length affected the slipstream velocity along the entire train length at the lower and upper regions of the side of the train.However,no significant effect was recognized at the middle height of the train along its length,except in the nose region.Moreover,within the train’s side regions(y=2.0-2.5 m and z=2-4 m)and(y=2.5-3.5 m and z=0.2-0.7 m),the ratio of slipstream velocity U_(max) between the short and long nose trains was notably higher.This occurrence also manifested at the train’s upper section,specifically where y=0-2.5 m and z=4.2-5.0 m.Similarly,regarding the ratio of _(max)imum pressure peak-to-peak values Cp-p_(max),significant regions were observed at the train’s side(y=1.8-2.6 m and z=1-4 m)and above the train(y=0-2 m and z=3.9-4.8 m).
文摘为了快速、准确分析螺旋桨滑流对增升装置的影响,采用实桨非定常方法(full blades method,FBM)和定常动量激励盘方法(actuator disk method,ADM),数值计算分析了前进比J=0.7、1.0,攻角α=–4°~24°工况下螺旋桨滑流对高升力构型的影响。研究表明:虽然从单独螺旋桨获取的时均化激励盘载荷分布与从高升力构型螺旋桨获取的存在局部差异,但将来源不同的激励盘载荷应用于ADM计算时,所得高升力构型的压力分布、升阻力结果基本一致,全机升力系数差异不超过4.3%,阻力系数偏差小于5.4%,说明采用单独螺旋桨获取激励盘载荷对全机气动力计算影响不大,从而避免了复杂的网格生成。ADM将非定常计算转化为定常计算,在保持网格量相当(3300万)的条件下,其计算结果与FBM结果在失速前(α<20°时)基本吻合,同时计算核时约降低至FBM的1/18(170/3100)。因此ADM方法能够高效、合理评估出螺旋桨滑流对增升装置产生的影响。
