尾随半挂车队列行进的轿车燃油经济性研究

为了精确研究队列中汽车的燃油消耗情况,以一辆轿车尾随一辆半挂车为例,对轿车队列尾随过程进行数值模拟,得到尾随过程中轿车的气动阻力系数. 建立轿车散热器-风扇一维散热模型,得到轿车风扇的功率,利用汽车行驶方程,推导得到基于气动阻力系数及风扇功率的车辆净燃油节省率公式,研究队列中尾随轿车的燃油经济性. 结果表明：发动机舱散热对尾随轿车的燃油消耗有一定影响,且间距越大影响越大;轿车的净燃油节省率随车间距的增大而减小,在间距为0.5至1.0倍轿车车长内时,轿车的净燃油节省率对间距变化最敏感.     

汽车外形对智能车辆队列行驶气动特性的影响

为了研究智能交通系统中不同外形车辆在队列行驶时的空气动力特性,以及车辆纵向间距对队列行驶车辆气动特性的影响,采用数值模拟方法对阶背式、快背式和直背式轿车5车队列分别在6种纵向间距下的气动特性了进行研究。结果表明:三种车型队列的平均减阻率大约为10%~40%,节省燃油5%~20%。阶背式轿车队列的平均减阻率最大,直背式次之,快背式最小。随着纵向间距的减小,每辆车的升力都增大,稳定性都变差。     

队列行驶车辆的空气动力特性

为了研究队列行驶时,车辆前后间距对队列行驶车辆气动特性的影响以及队列中车辆数目对气动阻力系数的影响,采用数值模拟方法分别对智能交通系统中队列行驶车辆11种不同情况下车辆的气动特性分别进行了研究。结果表明:队列行驶车辆随车间距离的缩短,阻力值降低。在固定间距下,随着队列中车辆数目的增加,平均阻力系数可降低20%—30%,阻力最低的车大致处于车队的中心位置。     

Aerodynamic drag analysis of double-deck container vehicles with different structures

To study the aerodynamic performance of a new six-axis X2K double-deck container vehicle,numerical simulation was done based on three-dimensional,steady Navier-Stokes equations and k-ε turbulence model.The results show that the pressure on the front surface of vehicle is positive,and others are negative.The maximum negative one appears as a gate shape on front surfaces.The pressure on vehicle increases with train speed,and pressure on vehicles with cross-loaded structure is smaller than that without it.The ...     

道路营运新能源汽车减碳测算

测算车辆运行碳排放,包括燃料消耗直接碳排放与电能利用间接碳排放。基于质量平衡法得出各种燃料的碳排放系数,基于火力发电煤耗量提出纯电动汽车间接CO₂排放计算方法。采集车辆运营数据与能耗数据,计算出各运输类型与各能源类型车辆CO₂年度排放量,得出电动车辆替代传统燃料车辆后的CO₂减排率。发现除大型柴油公交及中短途城际运输车辆外,电动汽车均有明显减碳效果,小型城市配送车辆减碳率最高,达48.62%。预测火电占比降低及火力发电煤耗量降低后电动汽车的碳减排量,相对于2016年,2020年将再减碳7.07%。     

Aerodynamic coefficient of vehicle-bridge system by wind tunnel test

The changes of three components of aerodynamic force were discussed with the attack angle conversion for three kinds of section models. Based on the project of Shanghai Yangtze River Bridge, the wind tunnel test was conducted to obtain its three components of aerodynamic force including 75 conditions of the construction stage, the bridge without vehicles and the bridge with vehicles from - 12 degrees to ＋ 12 degrees. For the bridge with vehicles, the drag force coefficient and the absolute value of both lift coefficient and moment coefficient were decreased by the vehicles. The test resuh shows that the bridge railing and vehicles have much influence on the three components of aerodynamic force of the vehicle-bridge system for Shanghai Yangtze River Bridge.     

Aerodynamic Analysis and Simulation of Flapping Wing Aerial Vehicles on Hovering

In order to design and verify control algorithms for flapping wing aerial vehicles(FWAVs),calculation models of the translational force,rotational force and virtual mass force were established with the basis on the modified quasi-steady aerodynamic theory and high lift mechanisms of insect flight.The simulation results show that the rotational force and virtual mass force can be ignored in the hovering FWAVs with simple harmonic motions in a cycle.The effects of the wing deformation on aerodynamic forces were investigated by regarding the maximum rotational angle of wingtip as a reference variable.The simulation results also show that the average lift coefficient increases and drag coefficient decreases with the increase of the maximum rotational angle of wingtip in the range of 0-90°.     

大型载货汽车驾驶室与货厢间隙对气动力特性的影响

以简化的大型载货汽车模型GTS为研究对象,采用RNGk-ε湍流模型和混合网格技术,分别模拟了气流流过驾驶室与货厢之间不同长度的间隙时产生的流场形态。通过分析不同间隙区域的流场形态分布和空气阻力系数的变化规律发现,间隙长度G≤55%时,对整车的气动力特性的影响较小;当G>55%时,气动力特性的变化对整车的影响逐步增大。同时研究发现,在GTS模型的驾驶室顶部加装导流罩可改善整车的气动力特性。     

微型燃气涡轮机增程式电动汽车设计

为提高纯电动轿车的适用性,弥补其续驶里程的缺陷,提出以微型燃气涡轮机作为增程器的增程式电动汽车开发方案.对主要动力总成及零部件进行分析,并根据分析确定整车参数,对主要零部件进行计算选型,在Advisor中对整车模型的可行性和燃油经济性进行了仿真验证.仿真结果表明:所提出的设计方案在纯电动模式下可以满足大部分人的需求,在增程模式下,平均每百公里等价油耗为2.02L.该设计方案提升车辆的燃料适应性,同时充分利用了电网能量,相比于传统车,燃油经济性也有很大提升.     

活性剂对水下航行体减阻特性的影响

为减小水下航行体的阻力,研究通活性剂溶液的水下航行体湍流减阻的流动特性.通过从航行体头部向航行体边界通活性剂溶液的方法,分别对不同质量浓度和不同速度情况进行减阻实验研究,并分析了不同攻角下活性剂溶液对阻力和升力的影响.实验中活性剂溶液质量浓度分别为200、400、600、800和1 000 mg/L,流速为4~10 m/s,对比分析了阻力系数.实验结果表明:在活性剂溶液质量浓度为200 mg/L时航行体减阻效果较弱,当活性剂溶液质量浓度增加到1 000 mg/L时,减阻百分比高达40.8%;在活性剂质量浓度为1 000 mg/L时,当水流速度从4 m/s逐渐增大到10 m/s,减阻百分比在12.5%和40.8%之间变化;活性剂对有攻角的航行体仍然有减阻效果并且对升力产生较小影响.     

Numerical exploration on jet oscillation mechanism of counterflowing jet ahead of a hypersonic lifting-body vehicle

Numerical investigation of a supersonic jet from the nose of a lifting-body vehicle opposing a hypersonic flow with the freestream Mach number being 8.0 at 40 km altitude was carried out by solving the three-dimensional, time-accurate Navier-Stokes equations with a hybrid meshes approach. Based on the analysis of the flow field structures and aerodynamic characteristics, the behaviours relevant to the LPM jet were discussed in detail, including the drag reduction effect, the periodic oscillation and the feedback loop. The obtained results show that the flow oscillation characteristic of the LPM jet is low-frequency and high-amplitude while that of the SPM jet is high-frequency and low-amplitude. Compared with the clearly dominant frequencies of the LPM jet, the SPM jet exhibits a broad-band structure. The LPM jet can sustain drag reduction effect until the angle of attack is 8°, and the lift-to-drag ratio of the vehicle is effectively improved by 6.95% at angle of attack of 6°. The self-sustained oscillation process was studied by a typical oscillating cycle of the drag force coefficient and the variation of the instantaneous pressure distribution,which reveals an off-axial flapping motion of the conical shear layer. The variation of the subsonic recirculation zone ahead of the vehicle nose strengthens the understanding of the jet behavior including the source of instability in the long penetration mode and the mechanism of the feedback loop. The aim of this paper is to advance the technology readiness level for the counterflowing jet applied as an active control technology in hypersonic flows by gaining a better insight of the flow physics.     

车架刚度对商用车乘坐舒适性的影响

为研究车架的刚度对商用车行驶平顺性的影响,建立整车三维(3D)有限元模型。给出了相应的加速度响应功率谱密度及均方根值的计算方法。用两种刚度的车架计算了驾驶室地板中点在4种激励情况下的加速度功率谱密度及均方根值。计算结果表明,提高车架的刚度可极大减少驾驶室地板振动加速度响应14～26Hz频带的均方根值,有效改善驾乘舒适性。     

重型商用车驾驶室空气悬置系统的匹配优化

采用虚拟样机技术建立了重型商用车驾驶室空气悬置多刚体动力学仿真模型,通过道路试验对仿真模型进行了验证,分析了其模态特性及乘坐舒适性。以驾驶室悬置元件刚度、阻尼为因子,运用正交试验技术对驾驶室悬置系统参数进行了匹配优化,结果表明,采用优化后的驾驶室空气悬置参数可使驾驶室的乘坐舒适性有一定程度的提高。     

Shock control bump optimization for a low sweep supercritical wing

Shock control bumps are a promising technique in reducing wave drag of civil transport aircraft flying at transonic speeds.This paper investigates the optimization of 3D shock control bumps on a supercritical wing with a sweep angle of 16°at the1/4 chord.A similar supercritical wing with a higher sweep angle of 24.5°at the 1/4 chord has been adopted as a baseline for the study.Numerical results show that the drag coefficient of the low sweep wing with the optimized 3D shock control bumps is reduced below that for the high sweep wing,indicating shock control bumps can be used as an effective means to reduce the wave drag caused by reducing the wing sweep angle.From the point of view of the wing structure design,lower sweep angle will also bring the benefits of weight reduction,resulting in further fuel reduction.     

全浮式驾驶室商用车平顺性分析系统开发

基于多刚体动力学理论以及虚拟样机技术，采用ADAMS软件为平台，设计开发了全浮式驾驶室商用车平顺性分析系统。给出了系统需求以及总体设计方案、功能模块设计、菜单设计以及对话框设计及模块功能的实现。最后利用所设计的系统对某款商用车进行了平顺性分析。     

大跨度双层桁架主梁三分力系数识别

采用风洞试验与计算流体力学（CFD）相结合的方法,对某公铁两用斜拉桥双层桁架主梁在?10°~10°风攻角下的三分力系数进行研究. 利用风洞试验技术测试成桥及施工阶段不同风攻角下主梁的气动力,并识别相应的三分力系数;基于标准k-ε双方程湍流模型建立三维数值计算模型,识别不同风攻角下三分力系数结果,并将其与风洞试验结果对比;结合2种方法研究雷诺数、桥面附属物和公路及铁路交通状况等因素对主梁气动特性的影响. 结果表明低风攻角下雷诺数对主梁气动特性影响较小,可忽略不计,并提出了高风攻角下识别双层桁架三分力系数最低雷诺数的建议值;桥面附属物对主梁阻力系数影响显著,下层桥面附属物有效降低了主梁升力系数;公路车辆对主梁气动系数影响较小,迎风侧列车对主梁阻力系数、升力系数影响显著,背风侧列车对主梁力矩系数影响显著.     

车辆在交叉口燃油消耗的研究

行驶在城市道路上车辆的油耗主要受行程车速、停车率和延误等交通状况的影响，本文应用汽车行驶理论分析交通状况如何影响车辆油耗，并运用模拟技术通过对油耗试验结果和调查数据的分析建立了车辆耗油与交通状况的相关模型，同时，也讨论了需进一步研究的方向。     

底部上翘角对轻型客车气动特性影响的数值模拟

用数值模拟的方法,研究轻型客车底部上翘角对其气动特性的影响规律.以某国产轻型客车1:5简化模型为研究对象,对具有不同底部上翘角的轻型客车进行了数值模拟,通过对气动阻力和气动升力的分析,得出底部上翘角度对轻型客车气动特性影响的规律.计算和分析的结论可以为轻型客车的减阻研究、造型优化和新车型开发提供科学的理论依据.     

考虑横向载荷转移的重型车辆建模研究

横向载荷转移是造成车辆侧翻的重要因素之一,在传统的计及侧倾的重型车辆动力学模型中并没有予以考虑,在对整车建模时假设簧下质量不存在侧倾角,对簧下质量单独分析时又考虑了其侧倾角,建模过程中各变量的正负号规定自成系统,没有统一的方向规定,造成对车辆的各部分受力分析不准确,本文建立的模型将横向载荷转移量作为一个变量来考虑,对整车建模时考虑了簧下质量侧倾角,统一了变量的正负号,建立了正确合理的适用于分析重型车侧倾稳定性的动力学模型。     

基于35°Ahmed模型的外流场仿真精确性与被动控制减阻研究

基于商用CFD计算软件STAR-CCM+,对常见的类车体35°Ahmed模型进行外流场仿真精确度研究,主要从网格类型、湍流模型、网格尺寸3个方面,通过对模型总压差阻力系数、局部的压差阻力系数、模型尾部斜面上方流场选定点的流速3个层级的分析,研究汽车外流场的仿真精确性, 寻找到一种可以接受并能应用于工程的仿真方法,即主体网格是四面体网格、k - w湍流模型、网格尺寸控制在较小量级的高质量仿真策略。在此基础上,通过在35°Ahmed模型尾部斜面添加凸起结构,进行35°Ahmed模型被动控制减阻技术研究,表明35°Ahmed模型的阻力主要来源于模型尾部,在模型尾部添加凸起结构,当附加板与斜面角度为30°时,有最优减阻效果。