两栖车辆绕流场数值模拟及外形优化

应用计算流体动力学理论,对两栖车辆车体模型带自由表面的粘性绕流场进行了数值模拟,得到了其粘性绕流场分布、阻力和兴波特性。在此基础上,对某型两栖侦察车外形进行了初步优化,分析比较了改进前后模型的流场特性。     

队列行驶领航车辆尾流的粒子图像测速试验研究

为了研究队列行驶时不同的车间距对领航车辆气动阻力的影响,采用风洞试验方法,分别测量了队列行驶工况下领航车辆和领航车辆单独行驶时的阻力系数.又运用粒子图像测速技术对以上工况中领航车辆尾部纵对称面内的流场进行了测量与分析.结果表明:随着车间距的缩短,领航车辆阻力值降低,降幅最大达41.66%,并且尾部流场的涡的拖曳距离、扩...     

基于Fluent进气系统流场数值模拟与结构优化

针对某车型平台上4A91S发动机进气系统结构,提出了基于CFD的结构优化方法。利用Fluent对该进气系统进行数值模拟,分析其流场特性,以发动机进气阻力最小和气体流动均匀为优化目标,改进对发动机进气阻力和流动均匀性影响大的结构因素。对比进气系统结构改进前后的流场特性,为汽车进气系统结构设计提供相应参考。     

基于流体动力学仿真的机油冷却器水道优化设计

针对某柴油机机油冷却器水道阻力较大,影响到发动机工作性能的问题,采用三维计算机流体动力学(CFD)软件对机油冷却器进行流场分析及阻力模拟。根据模拟结果,找到流体阻力大的原因,对模型进行了优化设计。对优化后的模型进行再次模拟,以确定最优方案,并对优化后样品进行阻力测试,以验证仿真结果的准确性,为后续机油冷却器的设计提供数据支持。     

高速列车通过隧道流场的三维数值模拟

应用三维粘性、非稳态不可压缩流的数学模型,对高速列车通过隧道时隧道内的压力变化、列车受到的气动阻力等问题进行分析研究,得到了隧道内的压力流场三维分布图,求出了速度、阻塞比等参数与压力、气动阻力之间的数值关系,为解决高速列车通过隧道引起的空气动力学问题提供参考。     

客车进气系统阻力的Fluent分析

利用Fluent对客车进气管路内部流场进行模拟,计算进气系统中压力损失。结果表明,利用Fluent模拟得到的结果与实验结果的误差为4.13%,能够快速、准确地计算进气管路阻力值,从而在设计之初合理评估进气系统阻力,确保进气系统设计成功率。     

摩托车及驾驶员气动特性的数值模拟研究

基于计算流体力学(CFD)的数值模拟技术,研究摩托车部件及驾驶员对整车气动特性的影响.对通过数值模拟获得的摩托车周围的流场、气动阻力系数和速度分布进行了深入分析;就风挡导流罩、驾驶员和摩托车本身的不同组合对整车气动阻力的影响进行了归纳;最后提出了一些减小摩托车气动阻力的具体建议.     

汽车底部复杂流场的主动和被动控制减阻方法研究

针对汽车底部复杂流场结构存在的问题及其对汽车燃油经济性的影响,以降低气动阻力为目标,采用计算流体动力学方法研究了侧风工况下汽车底部复杂流场的主动和被动控制减阻方法,设计了阻流板、侧裙、底部抽吸控制槽和尾部气流喷射控制槽4种减阻方案,分析了各方案对气动阻力的影响和减阻机理。研究结果表明,减阻效果与横摆角、阻流板高度、侧裙高度、底部控制槽抽吸速度和尾部控制槽气流喷射的速度与角度有关,4种减阻方案的气动阻力最大降幅分别为9.4%,10.4%,13.5%和4.7%。在实际使用过程中,宜根据汽车运行环境采用动态控制方法,以达到最优减阻效果。汽车模型风洞实验验证了本文中数值计算方法的准确性,研究结果可为汽车设计提供参考。     

某电动车底部后端的降阻研究

文章基于仿真分析的方法,针对某电动汽车的底部后端区域进行了降阻研究。研究发现,当电动汽车后端没有挡板覆盖时,后端零件的压力损失较大,使得整车气动阻力较高。通过增加后端挡板,可以有效改善底部后端的流场分布,改善整车的气动阻力。挡板的角度和高度对于挡板的气动阻力影响较大,在实际开发中需要进行优化。研究表明,当挡板角度为30°、高度为-5 mm时,对整车气动阻力的贡献量最大,整车Cd值降低了0. 005。     

某MPV车型的尾翼气动优化研究

为优化某MPV车型的气动性能,基于风洞试验结合试验设计优化方法对其尾部的尾翼零件包括尾翼本体和侧面饰板进行多参数的优化。通过在风洞试验中的优化获得了该车型尾部的气动最优造型方案,相比原始造型方案,整车阻力降低约2.9%。之后对优化前后的造型方案进行了CFD仿真,对比了优化前后的压力分布和流场的差异,分析了整车阻力降低的原因。最后通过对比整车各区和零件上的阻力变化进一步验证了阻力降低的原因,为MPV车型的尾部气动开发提供了优化方向。     

Aerodynamic Design of a Solar Road Vehicle

Solar road vehicles have very specific design requirements. This makes their aerodynamic characteristics quite different from classic sedan vehicles. In the present study, the computational model of a typical solar road vehicle was developed to investigate its aerodynamic forces and flow characteristics. Computations were performed assuming the steady viscous flow and using the Reynolds-averaged Navier Stokes equations along with the k-ω turbulence model. The obtained results indicate some important findings that are commonly not present for classic sedan vehicles. In particular, a contribution of the viscous drag force to the overall drag force is considerably larger (41 %) than it is the case for the standard passenger road vehicles, where the form drag force dominates over the viscous drag force. Surface pressure distribution patterns indicate a favorable aerodynamic design of this vehicle. In particular, larger pressure coefficients on the top of the vehicle body as compared to the bottom surface contribute to increasing a downforce and thus the vehicle traction. The airfoil-shaped crosssection of the designed cockpit canopy has favorable properties with respect to reduction of the aerodynamic drag force.     

圆顶车厢载货车外流场数值模拟及附加装置优化设计

对EQ1118GA圆顶车厢运输车进行外流场的数值模拟,通过对模型的表面压力和流场特性的分析,研究EQ1118GA运输车气动阻力产生的主要原因,以此为依据为优化其空气动力学性能设计了4种不同的导流罩,并分别对它们进行数值模拟计算,得到具有最佳减阻效果的导流罩。     

Comparative investigation on the aerodynamic effects of combined use of underbody drag reduction devices applied to real sedan

To reduce the aerodynamic drag, the performance of the underbody aerodynamic drag reduction devices was evaluated based on the actual shape of a sedan-type vehicle. An undercover, under-fin, and side air dam were used as the underbody aerodynamic drag reduction devices. In addition, the effects of the interactions based on the combination of the aerodynamic drag reduction devices were investigated. A commercial sedan-type vehicle was selected as a reference model and its shape was modeled in detail. Aerodynamic drag was analyzed by computational fluid dynamics at a general driving speed on highway of 120 km/h. The undercover reduced the slipstream area through the attenuation of the longitudinal vortex pair by enhancing the up-wash of underflow, thereby reducing the aerodynamic drag by 8.4 %. The under-fin and side air dam showed no reduction in aerodynamic drag when they were solely attached to the actual complex shape of the underbody. Simple aggregation of the effects of aerodynamic drag reduction by the individual device did not provide the accurate performance of the combined aerodynamic drag reduction devices. An additional aerodynamic drag reduction of 2.1 % on average was obtained compared to the expected drag reduction, which was due to the synergy effect of the combination.     

考虑来流偏角的汽车道路行驶阻力研究

汽车日益严苛的排放、油耗法规对准确测量和降低道路行驶阻力提出了更高的要求,气动阻力是汽车道路行驶过程中主要的阻力来源,真实道路自然风来流偏角是影响汽车气动阻力的重要因素。提出了一种基于真实道路来流偏角分布的风平均阻力系数计算方法——偏航角密度法,并和其他风平均阻力系数计算方法进行了比较,利用风洞法测量道路行驶阻力,研究了来流偏角对汽车道路行驶阻力、循环能耗的影响。研究表明,来流偏角概率密度呈现明显的区域分布特征,来流偏角显著影响汽车实际道路气动阻力、循环能耗,根据偏航角密度法,考虑真实道路来流偏角时,气动阻力、循环能耗分别最大可增加3.0%、1.6%。     

镂空式车顶扰流板关键参数对两厢车空气阻力的影响

镂空式车顶扰流板已成为一种汽车造型设计的新思路，对整车空气动力性能也有极大的影响。为了研究镂空式车顶扰流板对整车空气阻力系数的影响，基于比亚迪某款带有镂空式车顶扰流板的两厢车型，以 CFD仿真为主要开发工具，分别研究了扰流板角度、镂空通道和 D 柱扰流板的影响，并与风洞试验结果进行对标。研究发现，镂空式车顶扰流板的角度减小，镂空通道与后风挡距离减小，以及 D 柱扰流板延伸长度增大均会导致顶部尾流增大，使尾流上下匹配关系发生变化。当上下尾流匹配性更好时，空气阻力系数更低。该研究结果可为后续镂空式车顶扰流板的开发提供经验。     

轻卡外流场数值模拟及货箱优化设计

对某轻卡进行外流场的数值模拟,通过对模型的流场特性的分析,研究气动阻力产生的主要原因。将车厢高度和车厢与驾驶舱距离作为两个影响因子,采用拉丁超立方设计方法和最小二乘法创建二阶响应面模型,利用混合整型优化法进行参数优化,优化后与原型设计相比,整车气动阻力明显减小,表明该方法能有效地提高整车空气动力学性能和CFD优化效率。     

Actively translating a rear diffuser device for the aerodynamic drag reduction of a passenger car

This research aims to develop an actively translating rear diffuser device to reduce the aerodynamic drag experienced by passenger cars. One of the features of the device is that it is ordinarily hidden under the rear bumper but slips out backward only under high-speed driving conditions. In this study, a movable arc-shaped semi-diffuser device, round in form, is designed to maintain the streamlined automobile??s rear underbody configuration. The device is installed in the rear bumper section of a passenger car. Seven types of rear diffuser devices whose positions and protrusive lengths and widths are different (with the basic shape being identical) were installed, and Computational Fluid Dynamics (CFD) analyses were performed under moving ground and rotating wheel conditions. The main purpose of this study is to explain the aerodynamic drag reduction mechanism of a passenger car cruising at high speed via an actively translating rear diffuser device. The base pressure of the passenger car is increased by deploying the rear diffuser device, which then prevents the low-pressure air coming through the underbody from directly soaring up to the rear surface of the trunk. At the same time, the device generates a diffusing process that lowers the velocity but raises the pressure of the underbody flow, bringing about aerodynamic drag reduction. Finally, the automobile??s aerodynamic drag is reduced by an average of more than 4%, which helps to improve the constant speed fuel efficiency by approximately 2% at a range of driving speeds exceeding 70 km/h.     

汽车底部复杂流场数值模拟

针对汽车底部流场研究的困难，提炼物理数学模型，发展相应数值计算方法；对长安微型汽车外部复杂三维流场进行求解，计算风阻值与道路试验结果符合较好。在此数值计算结果基础上，对汽车底部复杂流场结构进行分析和研究。