车轮旋转对汽车流场影响的模拟研究

汽车车轮对汽车空气动力学特性有重要的影响。为了研究车轮旋转对汽车流场的影响,利用CFD方法,采用旋转壁面边界条件模拟汽车车轮旋转。建立了三维不可压缩雷诺平均方程,采用RNG湍流模型,利用二阶迎风差分格式获得控制体积界面上的物理量,应用SIMPLEC算法进行迭代计算．对汽车流场进行模拟仿真,并将结果与车轮静止的情况下进行对比分析。研究结果表明：汽车车轮转动对整车流场有明显的影响,特别是对汽车前后轮周围、汽车侧面和底面有很大的影响：车轮旋转情况下,车轮的上半部分受到的压力明显比静止的时候受到的压力大．但总体上会产生一个向上的气动升力：汽车在车轮旋转情况下,阻力系数和升力系数比车轮静止情况下的低。     

旋转车轮气动效应的CFD仿真和风洞实验及减阻优化研究

本文中以上汽通用公司两款车型为研究对象,运用运动参考坐标系(MRF)方法中的多重参考坐标系(MRF)方案,模拟了车轮转动,对车轮静止和转动条件下汽车的气动特性进行了CFD仿真和风洞实验。通过仿真与风洞实验结果的对比,验证了MRF方法模拟车轮转动气动效应的准确性。基于流场仿真结果分析了转动车轮气动阻力的产生机理和转动车轮对尾流结构和尾端压力的影响,探讨了车轮转动引起整车C_d变化的流场作用机理。根据流场分布特点提出车轮减阻优化方案,仿真结果表明,最优方案能显著降低C_d。本研究提供了准确模拟车轮转动气动效应的流场CFD仿真方案,分析了车轮转动相关的复杂流场相互作用机理,为车轮和尾端区域气动优化开发提供了有益参考。     

旋转车轮对汽车外部复杂流场的影响

车轮影响着整个汽车的外流场特性,车体周围的流场由于旋转车轮的存在而复杂化。通过对带有车轮的汽车模型进行数值模拟计算．比较无车轮、静止车轮和旋转车轮的计算结果,得到旋转车轮对汽车的尾涡结构、气动阻力和气动升力有重要影响。车轮在汽车外部复杂流场的数值计算中不能被忽略。     

基于CFD的尾翼对汽车稳定性数值分析

文章以一种常见轿跑车为分析对象,采用CFD计算方法对高速行驶过程中的汽车进行三维数值模拟,对车体加设尾翼装置前后的外流场进行了分析研究。考察了尾翼装置对汽车空气动力特性的影响,为实际生产提供一种高效设计手段。通过分析发现加装汽车尾翼装置可以增加车体表面压力加大车轮对地面的附着力,同时改变汽车尾部流场,降低了尾部因气流回旋造成的升力。虽然安装尾翼装置后汽车能耗会在一定程度上增加,但是可以大大提高汽车的行驶稳定性。     

汽车在环境风洞内流场的数值模拟与实验研究

为研究汽车在环境风洞内的流场特性,建立了环境风洞和整车数值模型,考虑了风洞喷口和收缩段的阻塞效应、边界层抽吸以及实验设施等对汽车流场的干扰效应,对环境风洞内汽车前方、车身和车轮周围、冷却模块以及机舱内的流场进行了数值模拟。对车身表面的静压以及车身周围和车底部的风速等进行测试,通过数值模拟结果与实验结果的对比,表明数值风洞能准确预测汽车在环境风洞内的流场特性。研究结果显示：汽车前端气流的速度分布沿着气流方向发生显著变化,越接近前端冷却模块时风速的均匀性变得越差;汽车底部气流受地面、车底和轮胎旋转等的共同影响呈现规律性的变化,车底风速沿车身纵向先增大后减小。本方法对研究汽车在环境风洞内的热气动性能以及开发数值风洞提供了新的思路和参考。     

轮辋结构对制动盘散热性能的影响分析

汽车轮辋结构直接影响着车轮区域的气流运动,进而会对车轮制动盘散热特性产生影响。为探讨轮辋结构对制动盘散热性能的影响,文章以窄轮辋、宽轮辋和全封闭轮辋三种轮辋结构为对象,从而实现对轮辋开口面积的改变,采用计算流体动力学分析了不同轮辋结构对车轮区域流场和制动盘散热性能的影响。结果表明,轮辋开口面积的大小和制动盘的散热效率成正相关,增加轮辋开口面积会增强车轮区域的气流运动,相应的制动盘散热效果呈现增大趋势。研究结果为车轮设计和制动盘散热优化改进提供指导。     

基于SIMULINK的汽车高速行驶姿态的影响因素分析

基于MATLAB/SIMULINK,以3自由度汽车非线性动力学模型为基础,建立仿真模型对汽车行驶姿态进行仿真研究,并且模拟了汽车在极限行驶工况下的行驶姿态,较低的行驶速度,适当增加侧倾转向系数可以提高汽车的操纵稳定性。前正/后负车轮外倾角可以保证汽车在高速转向/制动时保持一定的恢复横摆力矩,提高行驶安全性。改变侧倾阻尼系数对高速转向的操纵性影响不大而对行驶的平顺性有较大影响。     

CFD仿真在汽车轮辋辐板设计中的应用研究

应用计算流体动力学(CFD)的方法,在STAR-CD软件平台下对6个具有不同轮辋辐板的汽车车轮外流场进行了CFD仿真,解决了车轮接地区域网格生成的难题。探讨了辐板几何参数不同时车轮及其整车的阻力变化规律。通过对轮腔内速度矢量以及车身底部流线等试验结果的分析,总结出了辐板不同时车轮与汽车外流场的变化规律,为车轮辐板的设计提供了空气动力学理论依据。     

基于ANSYS workbench的车轮疲劳强度分析

车轮是汽车上的重要部件,它承受车身的重力、驱动力、制动力以及汽车转弯时的横向载荷,对汽车的行驶安全性、稳定性和平顺性都有着非常重要的影响。采用有限元分析的方法可以在新产品设计初期分析出车轮的强度和疲劳寿命,大大缩短设计周期。本文以14×5.5J车轮为研究对象,采用三维建模软件pro/E对车轮进行建模,利用有限元分析软件ANsYs worl出ench对车轮弯曲疲劳强度试验进行模拟,得到车轮强度和疲劳寿命的分析结果。     

主动悬架系统对汽车加速性能改善分析

针对前轴驱动汽车加速过程中质量转移而使最大驱动力下降的问题，提出了利用主动悬架系统减小汽车车轮动态载荷对其进行改善的方法，并进行了控制系统的设计。模拟分析表明，利用主动悬架系统可以有效地降低前轴驱动汽车由于质量转移而引起的车轮动载荷的改变，是解决加速过程中驱动力下降的一个比较有效的方法。     

An investigation into the mechanism of the out-of-round wheels of metro train and its mitigation measures

This paper presents an investigation into the mechanism of polygonal wear of metro train wheels through experiments conducted at field sites. The experiments comprise dynamic behaviour test of vehicle and track system, the wheel transverse wear and polygonal wear measurements, rail corrugation and rail weld joint irregularities’ measurements. Moreover, the numerical modal analysis of the wheelset is also performed. The wheel measurement results show that most wheels exhibit obvious eccentricity and polygonal wear with 5–8 harmonics. The investigation results indicate that the wavelength-fixing mechanism of the wheel out-of-roundness with 5–8 harmonics is the P2 resonance. Four measures have been proposed to mitigate the formation of wheel polygonal wear based on the field measurement results.     

Vehicle steering returnability with maximum steering wheel angle at low speeds

In this paper, an analytical model with suitable vehicle parameters, together with a multi-body model is proposed to predict steering returnability in low-speed cornering with what is expected to be adequate precision as the steering wheel moves from lock to lock. This model shows how the steering response can be interpreted in terms of vertical force, lateral force with aligning moment, and longitudinal force. The simulation results show that vertical steering rack forces increase in the restoring direction according to steering rack displacement for both the inner and outer wheels. As lateral forces due to side-slip angle are directed toward the medial plane of the vehicle in both wheels, the outer wheel pushes the steering wheel in the returning direction while the inner wheel does not. In order to improve steering returnability, it is possible to increase the total steering rack force in both road wheels through adjustments to the kingpin axis and steering angle. This approach is useful for setting up a proper suspension geometry during conceptual chassis design.     

电动轮驱动的电动汽车动力学仿真

采用自然坐标系下的整车动力学模型,模拟变速或转向过程中可能存在的变化情况,进行了四电动轮独立驱动的电动汽车仿真。仿真试验表明,在变速或转向的过程中,各轮的输出转矩可能会有较大差异。因此在此类电动汽车的设计中应当充分考虑对变速或转向时各轮的转矩加以控制,以提高操控性能。     

汽车轮速传感器仿真方法

轮速传感器测量汽车轮速信号,用于制动、发动机及变速箱等众多系统控制,是汽车最关键的部件之一。新车型开发阶段,为了对汽车制动防抱死系统(ABS)及早有效的开发验证,需要对轮速传感器进行仿真模拟。文章针对最常用的主动式轮速传感器进行测试与分析,通过设计信号调理电路,成功搭建了ABS硬件在环仿真平台,既简化了汽车开发阶段的验证与测试,又节省了开发成本。     

汽车轮胎压力监测系统中的动态天线研究

由于汽车轮胎压力监测系统(TPMS)中的无线温度压力传感器安装在轮毂上,金属的轮毂、车身以及轮毂的转动对无线传感器天线的性能影响很大,使TPMS的性能下降。针对该问题提出将无线传感器天线、轮毂、车身看作一个动态天线,建立动态天线的三维电磁场仿真模型,并将仿真得到的动态天线参数用于无线传感器天线的匹配电路设计。道路试验显示:设计的TPMS系统安装在汽车轮毂上且处于运动状态时,性能良好,说明动态天线的三维电磁场仿真模型可用于TPMS的优化设计。     

The effect of worn profile on wear progress of rail vehicle steel wheels over curved tracks

Dynamic performance, safety and maintenance costs of railway vehicles strongly depend on wheelset dynamics and particularly on the design of wheelset profile. This paper considers the effect of worn wheel profile on vehicle dynamics and the trend of wear in the wheels as a result of the vehicle movements. ADAMS/RAIL is used to build a multi-body system model of the vehicle. The track model is also configured as an elastic body. Measured new and worn wheel profiles are used to provide boundary conditions for the wheel/rail contacts. The fleet velocity profile taken during its normal braking is also used for the simulation. Wear numbers are calculated for different sets of wheels and the results compared with each other. Outcome of this research can be used for modifying dynamic performance of the vehicle, improving its suspension elements and increasing ride quality. It can also be further processed to reach to a modified wheel profile suitable for the fleet/track combination and for improved maintenance of the wheels. A major advantage of the computer models in this paper is the insertion of the wheel surface properties into the boundary conditions for dynamic modelling of the fleet. This is performed by regularly measuring the worn wheel profiles during their service life and by the calculation of the wear rate for individual wheels.     

Efficiency analysis of a multiple axle vehicle with hydrostatic transmission overcoming obstacles

Transmission configurations in off-road vehicles with multiple driven axles can be a determining factor in the obstacle surmounting capacity and also in the vehicle efficiency. An off-road articulated vehicle with four driven axles, four bogies and two modules has been considered for the global hydrostatic transmission efficiency analysis and for the vehicle functional efficiency analysis. The power flow through the transmission system has been quantified from the combustion engine shaft to each axle of the wheels. It has been done for different the operating conditions and taking into account the wheel–terrain interaction and the transmission configuration, that could lead to a forced slippage of some of the wheels. Results show the influence of the different wheels’ requirements, the transmission configuration limitations and the considered control strategy on the global transmission and vehicle functional efficiencies.     

重型越野汽车轻量化车轮设计开发

本文根据铝合金车轮在重型越野汽车上的工程应用,及其加工工艺,设计了铝合金车轮的结构型式及特性参数。并以ANSYS软件为工具,对越野汽车车轮进行受力分析,详细准确地确定了车轮的受力情况和应力分布部位,依托分析结果对车轮进行优化,达到降低车轮关键部位应力的目的。并通过实际装车试验验证,结果显示该重型越野汽车轻量化车轮产品设计的合理性、可靠性,解决了车辆轻量化的问题,提高了整车的质量利用系数。