汽车空调车室内气流和温度场的数值模拟

运用稳态不可压缩雷诺平均N-S方程,k-ε湍流模型,采用有限容积和交错网格将计算区域进行离散,对汽车车厢内三维空气流场和温度场进行了数值计算,考虑了太阳辐射和人体散热对速度场和温度场的影响。结果表明人体散热对气流的流场和温度场有较大的影响,太阳辐射对流场影响较小,但对温度场有较大的影响。研究结果为客车内气流组织的优化设计和舒适性提供了数据支持。     

高速列车客室内部流场计算流体动力学数值模拟

针对高速列车的车厢内温度场和流场进行CFD模拟分析,对车内热舒适性做出评价。本文计算得出列车车厢在4500m3/h的送风量和18℃的送风温度下,车厢内的平均温度约为24.9℃,PMV值介于0~1.0,车厢内的热环境为中等舒适状态。车厢内的空气龄较小,乘客区气流分布较为合理。部分区域,如行李架和车厢后部,存在温度偏高和空气龄较大的现象。     

置换通风条件下送风速度对污染物浓度分布的数值模拟

在置换通风条件下,建立了高大空间简化物理模型和污染物浓度控制方程,设定了相应的边界条件,以数值模拟的方式分析了送风速度对空间内速度场和污染物浓度场分布的影响。采用有限容积法对控制方程进行离散化,通用微分方程离散过程中,采用规则的结构网格进行网格划分。研究结果表明,当送风速度很大时,在热源附近形成的涡流越强烈,使热气流与周围空气的混合扩散作用增强,容易失去置换通风的效果;随着送风速度的增加,污染物浓度分布的高度随之增加,但掺混也会随之增强,采用置换通风对大空间室内污染物进行控制时,其送风速度应以0.25m/s为宜。     

采用近流线网格对NOx生成过程的数值研究

应用Fluent软件对某电厂450t/h四角切圆锅炉的燃烧过程进行数值模拟研究。通过对满负荷进行模拟计算,得到了炉内流场分布、温度场分布和各组分场分布。结果表明:ICEM所划分的近流线网格及所选择的计算模型能够满足炉内流动的计算要求;燃烧器射流区域氮氧化物大量生成,由于主燃区整体处在还原性气氛下,NO浓度会逐渐减少,随着燃尽风的给入NO浓度会有微量的升高,计算得炉膛出口处NOx与现场测量值非常接近。     

内隔断布置情况对地板送风房间空气品质影响的数值模拟分析

利用CFD对室内存在不同形式内隔断的地板送风办公房间进行了数值模拟,研究其速度场、温度场及污染物浓度场;分析了内隔断的存在对室内空气品质的影响。研究结果表明,在办公桌靠近送风口侧设置的隔断,能够在一定程度上阻挡由送风口处送出的冷风直接抵达人体脚踝处,有助于改善人体脚寒的情况。但围合型隔断的存在将导致隔间内形成涡流,使人体周围的气流速度增大,并影响CO2的扩散,不利于其顺利排出。     

洗涤器进气管角度优化数值模拟

运用数值模拟软件研究进气管角度对洗涤器内气流均匀性的影响;在不同进气管入口角度下进行洗涤器速度场三维稳态数值模拟,根据气流速度分布均匀性,找到最佳的进气管入口角度,从而使实际洗涤器内可不用安装气流分布板,并使进一步降低设备阻力成为可能;模拟结果表明,无论进气管形状如何变化,总存在着一个使洗涤器内流场较均匀分布的最佳入口角度,其范围在8°～18°之间.     

医护人员走动对ICU病房内气流分布的影响

考虑到ICU病房内医护人员走动的情况,运用FLUENT软件,采用动网格方法对某ICU病房内医护人员进行走动程序的设置,并对医护人员走动所引起的气流变化进行数值模拟。研究结果表明,ICU病房内医护人员的走动主要对医护人员尾部区域有一定影响,影响区域约为人体3倍身宽,使尾部区域气流速度以及颗粒物浓度较大,并且其气流速度与医护人员走动速度几乎保持一致;医护人员走动对病患区域影响较小,当医护人员接近病患时和在ICU病房内呼吸机和药品桌等医用设备附近时,由于走动引起的气流带动医用设备的颗粒物扬起扩散至病患附近。     

部分流低温液氮泵性能及流动特性仿真研究

对部分流低温液氮泵进行了外特性及内流场特性的数值模拟研究。通过两种数学模型及不同计算方法的对比,以扬程的预测差异为依据,确定了采用SIMPLEC压力耦合方式标准湍流模型最为精准,扬程偏差在4%以内。泵内流场的分析可知,泵的速度流场分布与部分流泵的设计理论相符;模拟的叶片头部的负压区验证了实验中的零压头现象。     

上海地铁A型车车厢体空调气流组织的模拟研究

利用计算流体力学软件对地铁A型车厢空调系统在不同工况下的温度场和速度值进行了数值模拟,就其所涉及的风口尺寸、位置、型式以及气流组织等方面定性地进行了比较分析,提出了一个优化方案,为车厢内气流分布的优化设计提供参考。     

街道峡谷内细微颗粒物扩散特性的DPM数值模拟

应用离散相模型(DPM)对城市中典型的街道峡谷内细微颗粒污染物浓度场进行了模拟,计算湍流模型选择标准k-ε双方程模型.计算结果表明,城市风场作用于街谷内导致涡旋流动,进而影响颗粒物的扩散分布.背风侧壁面颗粒物的浓度场呈现明显的"爬墙效应".不同几何结构影响颗粒物的浓度场,递增型街谷模型更有利于颗粒污染物的扩散.     

The actual threat posed by unrestrained rear seat car passengers

A statistical analysis of the threat posed by unrestrained rear seat car passengers to restrained drivers and front seat passengers was published in 2002. This was based on Japanese accident data from 1995 to 1999, and the conclusions have been checked using corresponding accident data from Great Britain. The law in respect of the use of seat belts and other restraint systems was less strict in Japan than in Great Britain between 1995 and 1999, so an earlier period had to be studied. The results suggest that the risk of death to a front seat car occupant is increased by about three-quarters by the presence of an unrestrained rear seat passenger behind them, a much smaller increase than was claimed by the Japanese researchers.     

小型民用客机座椅舒适性设计研究

目的研究一种机载小型民用客机座椅及其舒适性设计。方法通过对现有小型民用客机座椅的现状进行调研,建立小型民用客机座椅舒适性分析模型。结论指出小型民用客机中座椅及其组件的设计除了需要满足相应适航规章的要求与航空座椅人机工程学的要求外,还需在最大限度保证乘客乘坐安全的前提下,尽可能从座椅的造型、色彩、结构、材料等内容上,为乘客提供生理及心理两方面的舒适性感受。为此,研究给出了相应的设计方案。     

Vakuumbeschichtung von PET‐Folie mit Solar‐Control‐Schichten

Solar control coatings as an integrated part of automotive glass are increasingly used in a growing number of car models of all classes of the European car manufactures. The advantages of that solar control laminated glass are an increased reflection in the near infrared spectral region, which results in a reduction of heat gain of about 50 % in the cabin caused by solar radiation, an increase of passenger comfort and the safe of fuel for air conditioning. One process for the production of solar control coatings is the magnetron sputtering onto optical grade flexible PET‐film. The performance of these coatings as well as technological issues of the deposition process are presented.     

Passenger seating position and the risk of passenger death or injury in traffic crashes

OBJECTIVE: To estimate the association of passenger seat position with the risk of death and serious injury for passengers in traffic crashes. METHODS: Using 1993-2000 data from the National Highway Traffic Safety Administration's Crashworthiness Data System (CDS), the risk ratio for death and serious injury was estimated for rear seat passengers compared with front seat passengers in motor vehicle crashes. RESULTS: The adjusted risk ratio for death of passengers in the rear seat in a crash was 0.61 (95% confidence interval (CI) 0.46-0.81). Rear seat passenger position was also associated with a decrease in the risk of death and serious injury compared with the front seat passenger position: risk ratio=0.67 (95% CI 0.57-0.78). CONCLUSION: We estimated that the rear seat passenger position may reduce the risk of death in a motor vehicle crash by about 39% and reduce the risk of death or serious injury in a crash by 33%, compared with the front seat passenger position. If the associations that we report are causal, sitting in the rear seat, compared with the front seat, may prevent about 4 in 10 passenger deaths, or 3 in 10 passenger deaths and injuries, that might otherwise occur.     

空调客车车内空气品质控制系统的设计

客车空调注重满足人体热舒适的要求,对空气的清洁度重视不够,车内空气的污染物严重地影响乘员的健康。开发传感器准确、快速地测定空气的污染物,通过电子控制系统改善车内空气品质势在必行。介绍传感器的结构、原理及应用,并设计空调客车车内空气品质电子控制系统。     

PARTICULATE CONCENTRATION IN AUTOMOBILE PASSENGER COMPARTMENTS

An experimental study of the dust concentration in automobile passenger compartments was conducted to understand how driving conditions and a vehicle's ventilation system can affect cabin air quality. The results of this study are essential for designing appropriate cabin air filters and developing proper test procedures.

The particle size distribution of atmospheric contaminants entering the vehicle's passenger compartment through air registers and in the occupants' breathing zone was measured using an optical particle counter. The concentration and size distribution of aerosol in the cabin was found to be dependent on traffic conditions, road surface, environmental conditions (e.g., weather) and ventilation mode. In all cases over 90% of the particles were smaller than 1 µm. The vehicle's HVAC system (evaporator core) reduces the concentration of aerosol entering the car interior, especially larger particles. Commercial vehicle ventilation filters decrease particle concentrations in a driver's breathing zone for all particle sizes. However, the reduction in the submicron particle range is not sufficient to substantially improve air quality in the passenger cabin.     

Speed as a measure of driver risk: Observed speeds versus driver and vehicle characteristics

This investigation was performed to determine relationships between driver and vehicle characteristics and freely chosen speeds of cars on a two lane road with little commercial or residential development. Speed is taken as a measure of a driver's willingness to expose himself to risk of accident, in the same way that short freeway headways were interpreted in an earlier study. A total of 6638 passenger car speeds were measured by radar while each oncoming vehicle was simultaneously photographed. Driver and vehicle characteristics were derived from the photographs, both by direct observation (vehicle type, driver sex, presence of front seat passengers, seat belt use) and from the car license plate through the use of State vehicle registration and driver licensing files. The State files provided the car mass and model year and the owner (usually driver) age, sex, and recorded accidents and violations. Higher speeds were observed for younger drivers, drivers with prior accidents and convictions, newer cars, heavier cars and cars with no passengers.     

R1234yf整车汽车空调泄漏扩散研究

新能源电动汽车热管理系统与传统乘用车不同,对采用热泵空调系统并利用液冷冷却电池的新能源电动汽车,制冷剂充注量比传统汽车空调增加了400～800 g.若使用可燃制冷剂,泄漏扩散至乘员舱,燃烧风险将增大.本文通过数值模拟对R1234yf制冷剂在蒸发器破损泄漏随送风进入乘员舱后的浓度变化过程和最高浓度进行了动态监测.结果表明...     

Method to evaluate the effect of safety belt use by rear seat passengers on the injury severity of front seat occupants

Although the effectiveness of seat belts for reducing injury to rear seat passengers in traffic accidents has been well documented, the ratio of rear-seat passengers restrained by seatbelts remains lower than that of drivers or passengers in front seats. If passengers in rear seats do not wear seat belts, they may sustain unexpected injury to themselves when involved in accidents, and also endanger front occupants (drivers or front seat passengers). This paper focuses on the tendency of front seat occupants to sustain severer injuries due to forward movement of passengers in rear seats at the moment of frontal collisions, and evaluates the effectiveness of rear passengers' wearing seat belts in reducing injuries of front seat occupants. Since the occurrence of occupant injuries depends considerably on the crash severity, we proposed to use pseudo-delta V in regression analysis to represent velocity change during a collision when analyzing statistical accident data. As the crash severity can be estimated from pseudo-delta V, it becomes possible to make appropriate estimations even when the crash severity differs in data. The binary model derived from the ordered response model was used to evaluate the influence on the injury level based on pseudo-delta V, belted or unbelted status, gender and age. Occupants in cars with a hood in the case of car-to-car frontal collisions were extracted from the statistical data on accidents in Japan. Among 81,817 cars, where at least one passenger was present, a total of 6847 cars in which all passengers sustained injuries and which had at least one rear seat passenger aboard were analyzed. The number of killed or seriously injured drivers is estimated to decrease by around 25% if rear seat occupants come to wear seat belts. Also, the number of killed or seriously injured passengers in front seats is estimated to decrease by 28% if unbelted rear seat occupants come to wear seat belts. Thus, wearing of seat belts by previously unbelted rear seat passengers is considered effective in reducing not only injuries to the rear seat passengers themselves but also injuries to front seat occupants.     

Individual factors affecting the risk of death for rear-seated passengers in road crashes

We studied the effect of age, gender, use of restraint systems and seat position on the risk of death for rear-seated passengers of cars involved in road crashes. The data source was the Spanish register of traffic crashes with victims compiled by the Government's General Traffic Directorate. Data for crashes recorded from 1993 to 2002, inclusive, were studied. We used a matched cohort design to analyze all 5260 rear-seated passengers in vehicles occupied by two or three rear-seated passengers for accidents in which at least one of these passengers was killed. Conditional Poisson regression with death as the dependent variable was used. An increased risk of death was observed for females and children aged <3 years. For passengers aged 25 years and older, the risk increased with age. The use of restraint systems and central and right-side seats was associated with a lower risk. These results should be considered in research focused on passenger fragility and strategies to prevent injury and death.