Automobile defrosting system analysis through a full-scale model

Adequate visibility through the automobile windshield is of paramount practical significance, most often at very low temperatures when ice tends to form on the windshield screen. But the numerical simulation of the defrost process is a challenging task because phase change is involved. In this study numerical solution was computed by a finite volume computational fluid dynamics (CFD) program and experimental investigations were performed to validate the numerical results. It was found that the airflow produced by the defrost nozzle is highly nonuniform in nature and does not cover the whole windshield area. The nonuniformity also severely affected the heating temperature pattern on the windshield. The windshield temperature reached a maximum in the vicinity of the defroster nozzle in the lower part of the windshield and ranged from 9∼31°C over a period of 30 min, which caused the frost to melt on the windshield. The melting time was under 10 minutes, which satisfied the NHTSA standard. The numerical predictions were in close agreement with the experimental results. Thus, CFD can be a very useful design tool for an automobile HVAC system.     

汽车前风挡玻璃性能试验方法探究

现在汽车上常用的玻璃分为两种：夹层玻璃和钢化玻璃。前风挡玻璃主要是夹层玻璃,后挡和侧门玻璃多为钢化玻璃。尤其是前风挡玻璃,和乘员接触最近,保护作用作也最大,它与乘员安全息息相关,所以玻璃的生产前期试验验证就显得尤为重要。文章主要分析了汽车前风窗玻璃的结构,通过对比ISO,欧洲经济委员会（ECE）,中国国家标准（GB）,上海汽车（SAIC）,双龙汽车（Ssangyong）,名爵汽车（MG）,菲亚特汽车（FAIT）等试验标准,研究了前风窗玻璃的试验机理和试验方法,给出了相关的试验步骤和试验限值,对玻璃的质量控制有重大意义。     

客车前风挡玻璃粘接力计算分析

随着客车技术的渐渐成熟,人们对客车的安全系数有了越来越高的要求。尤其对于在公路上高速行驶的客车来说,安全因素是考虑的首要因素。以下针对客车前风挡玻璃在高速行驶,紧急制动情况下受力状态加以阐明。     

Automotive windshield — pedestrian head impact: Energy absorption capability of interlayer material

During accident, the interlayer of windshield plays an important role in the crash safety of automotive and protection of pedestrian or passenger. The understanding of its energy absorption capability is of fundamental importance. Conventional interlayer material of automotive windshield is made by Polyvinyl butyral (PVB). Recently, a new candidate of high-performance nanoporous energy absorption system (NEAS) has been suggested as a candidate for crashworthiness. For the model problem of pedestrian head impact with windshield, we compare the energy absorption capabilities of PVB and NEAS interlayers, in terms of the contact force, acceleration, velocity, head injury criteria, and energy absorption ratio, among which results obtained from PVB interlayers are validated by literature references. The impact speed is obtained from virtual test field in PC-CRASH, and the impact simulations are carried out using explicit finite element simulations. Both the accident speed and interlayer thickness are varied to explore their effects. The explicit relationships established among the energy absorption capabilities, impact speed, and interlayer material/thickness, are useful for safety evaluation as well as automotive design. It is shown that the NEAS interlayer may absorb more energy than PVB interlayer and it may be a competitive candidate for windshield interlayer.     

基于CFD方法的空调风管除霜性能开发

基于空调风管除霜性能开发过程,将总体性能分解到风管性能、玻璃近壁面的速度性能以及考虑温度的除霜性能。使用计算流体力学(CFD)方法,在设计前期通过稳态分析控制风管的性能及速度性能;在设计后期通过瞬态分析评估空调除霜的能力。分析结果表明,空调除霜性能目标从部件到整车均满足要求。     

商用车除霜性能提升方法研究

论述了影响汽车前风窗玻璃除霜系统性能的两个主要因素及具体要求;通过2个商用车的实际案例,分别研究如何通过优化除霜风道和提升发动机水温,从而改进前风窗玻璃表面风速分布和出风温度,最终实现除霜性能提升。     

某中体驾驶室的车身总布置设计

本文介绍了某重卡中体驾驶室车身总布置设计,首先对驾驶员A柱双目障碍角及左右后视镜视野进行校核,然后设计相应的雨刮器,并对所设计的雨刮进行运动分析、刮刷面积进行校核,校核结果均满足标准要求;最后以车身总布置图的形式将车身总布置设计及校核的其他关键参数体现出来。     

Analysis of neck fractures from frontal collisions at low speeds

Neck fracture is a major cause of death in traffic accidents. This pattern of injury normally occurs in a frontal collision or overturn of a vehicle. This study investigates the case of a neck fracture from a low-speed collision. In the examined case, the passenger in the front seat of the car fractured his neck and died. He did not have his seatbelt on when the vehicle slipped on a frozen road surface on a downward slope of a hill and impacted into the shoulder of the road at low speed. In this type of collision, an occupant’s body will be impacted by the windshield or other interior trim of the car. However, in this case, rather unusually, neither body tissue nor fiber remained although the collision involved a broken windshield. Thus, the reason for the passenger death was unidentified. This study applied the computer simulation package Madymo for analyzing the accident. The result of the simulation was that the passenger, who did not wear a seatbelt, moved forward due to inertia. The upper part of the passenger then rotated and lifted when the knee contacted with the dashboard. By evaluating the structural deformation of the vehicle at the front, we deduced that the collision velocity was 30 km/h. Through a computational experiment that was undertaken using Madymo 7.0, NIC was estimated to be 240 m²/s². This result far exceeded the threshold for neck injuries. In particular, in comparison with whiplash injuries, when the passenger’s head directly impacts the roof following a rear-end collision, the bending moment through hyperextension of the neck is greatly increased. In this study, we concluded that the manner of death was the hyperextension of the neck, as the passenger’s head contacted the roof from underneath.     

某款乘用车的俄罗斯市场适应性设计

某款乘用车出口俄罗斯市场,根据当地的市场要求,需要增加前排座椅加热、转向盘加热、前风挡玻璃除冰加热功能。介绍前排座椅加热、转向盘加热、前风挡玻璃除冰加热系统专用件设计,并据此做出专用件样件,样件在某款样车上实际试装测试,结果符合设计要求。本车型可以批量生产,出口俄罗斯市场。     

乘用车通风盖板断面设计要求

乘用车通风盖板在整车通风、排水、美观上起着重要作用,因其与前风挡玻璃、翼子板、发动机舱零部件相互配合,结构设计非常复杂,这就需要研发工程师要充分考虑通风盖板开发过程中的设计要求、法规要求、结构限制以及工艺要求和材料选择等因素,本文从通风盖板断面设计入手,重点介绍了通风盖板与对手件配合的断面设计要求。     

轿车白车身模态试验研究

通过对某型轿车4种不同状态白车身的模态试验,得到了各状态白车身的固有频率和振型,在此基础上分析了不同状态白车身结构频率分布特性及对整车NVH特性的影响。研究表明,该型轿车白车身的低频动态特性较好,局部模态特性有待改善;增加阻尼对车身模态特性有小的弱化作用;增加挡风玻璃对车身模态特性有一定改善;增加天窗对车身模态特性有较大的弱化。     

探究客车侧围结构接头焊缝间距的疲劳分析

客车在使用过程中,运行的安全性是人们最为关注的内容,同时也是保证交通运输的重要因素。而客车骨架的接头焊缝,对客车的使用质量具有重要影响。文章通过对客车侧围结构接头局部模型进行分析,提供了多种焊缝间距的疲劳性能对比结果,对焊缝间距和疲劳之间的关系进行了初步的分析判断。     

高原环境柴油机喷嘴内部流场与缸内温度场的三维数值模拟

采用广安博之等准维模型,建立柴油机高原运行工作过程模型;通过环境模拟台架试验验证了模型的可信性。将准维计算结果作为喷嘴内部气液两相流动和缸内燃烧三维模拟的初始条件,就高原低压、低温、低氧条件对喷孔内燃油流动状态与分布、缸内燃烧过程的影响进行三维数值模拟。海拔3 700m计算结果表明:与平原环境相比,柴油机喷嘴内空穴现象加剧,燃油流动速度增加,喷孔出口燃油分布不均匀度增加;缸内燃烧平均温度比平原最多高出300℃且分布不均匀,燃烧室局部热负荷偏高。研究初步揭示了高原环境柴油机性能劣化机理,为通过优化缸内喷雾和燃烧过程改善高原运行发动机性能提供参考。     

针对行人保护头部仿真分析中雨刮臂的接触设置研究

利用计算机进行有限元仿真分析,在汽车行人保护性能开发过程中有着广泛的应用。对于行人保护建模来说,风挡玻璃区域应按照实际情况对玻璃进行准确建模,然而对于风挡玻璃与雨刮器采用以往的接触设置,雨刮臂与玻璃产生穿透现象。因此为了解决穿透问题,准确模拟出其实际运动关系,对于雨刮臂与风挡玻璃之间的接触设置研究是非常有必要的。     

Study of melting phenomenon of frost and ice on the windshield

Frost and ice were accumulated on the windshield in winter. Generally to melt it, warm air using engine coolant is blown on the inner surface of the windshield, though, the time to melt is over 10 min under the lower temperature condition. In this study to shorten the melting time, the electric power systems of the heating element and the clear heating film were compared with the defroster system and the factors influencing the melting were investigated.     

提高面向中东市场乘用车的空调降温性能

某款乘用车出口中东市场,出现空调停止工作及空调降温性能不能满足当地高温环境要求的问题。经过分析并对发动机水泵、散热器、冷却风扇进行了改进,改进后的样件装车测试,空调工作不再出现停机现象,空调降温性能达到了中东地区高温环境的要求,此款乘用车可以顺利出口到中东市场。     

基于非结构化网格的汽车除霜风道数值模拟

利用基于非结构化网格的有限体积法对某一汽车风道进行了数值模拟,根据模拟结果对原型风道进行几何优化及计算.计算结果表明,优化后的风道各出口流量分配合理,压力损失明显降低,前挡风玻璃上的气流速度大小分布合理.利用热球风速仪测量了安装改型风道的样车前挡风玻璃上的气流速度.测量结果表明,与原型风道相比,改型风道样车前挡风玻璃上的气流速度明显增大,且分布更为均匀.     

中型汽车空调设计

对中型汽车空调系统的结构，功能及选型，空气循环方式，送气状态等进行了详尽的描述。此空调系统结构合理，性能先进，实现了中型汽车冬季采暖，除霜，夏季制冷，降温，除湿，使乘员有舒适的工作环境和良好的风窗视野，减轻乘员的疲劳，保证行车安全。     

3-D numerical and experimental analysis for airflow within a passenger compartment

People use cars so frequently that they always consider the air-conditioning, and thermal comfort of the driver and passenger when buying a new car. Therefore accurate simulation of the thermal performance of automobile air conditioners to improve human comfort has become increasingly important. In order to improve the thermal comfort of passengers, 3-D flow motion and thermal behavior within vehicles must be analyzed. In this paper, a numerical simulation was used to investigate thermal behavior in a vehicle. Because air temperature at an air vent is related to the cooling capacity of the air conditioner, the cooling capacity was calculated using ɛ-NTU (effective number of transfer unit) theoretical equations. Using the air temperature relationship between inlet and outlet vents as boundary conditions, a 3-D unsteady κ-ɛ turbulent model was used to give a transient analysis simulation of the temperature field and flow conditions in a vehicle’s passenger cabin. Cooling cycle analysis and conjugate heat transfer analysis at the inside surface of the cabin’s ceiling, floor and sides were also considered. The predicted temperature distributions in the vehicles passenger cabin were in good agreement with those obtained experimentally.