厢式货车飞翔导流罩仿真设计

随着中国汽车的飞速发展,我国汽车保有量呈明显上升状态,但目前汽车能耗依然居高不下,尤其高速公路上的厢式货车耗油量更是惊人,而气动阻力系数又是决定货车阻力大小的重要因素。     

基于3Dmax的高速公路厢式货车导流罩的仿真设计

为了有效减少厢式货车在高速行驶时的气动阻力.提出了基于3Dmax建模的高速公路厢式货车导流罩设计.以高尔夫球表面的凹坑设计为思路,以改进类似设计的弊端为目标,运用3Dmax建模设计导流罩.对该模型进行分析模拟后.结果表明该设计对高速行驶中厢式货车的减阻效果显著,具有广泛的应用前景.     

一种货车尾部的飞翔导流罩仿真设计

为了有效减小厢式货车在高速行驶过程中的气动阻力,提出了基于3Dmax建模的高速公路厢式货车导流罩设计,命名为飞翔导流罩。以高尔夫球表面的凹坑设计为设计思路,以改进类似设计的弊端为目标,运用3Dmax建模设计此导流罩。对该模型进行分析模拟后,结果表明该设计在高速行驶厢式货车的减组中,具有广泛的应用前景。     

导流罩对冰箱冷凝风机噪声的影响

为研究不同的导流罩对冰箱冷凝风机噪声的影响,利用数值模拟的方法对风机在不同导流罩下的流动特性进行仿真,得到不同导流罩下风机后缘涡流的分布,获取风机出口的湍流强度的变化特性,并进行相关的分析。通过试验验证表明,使用封闭式导流罩时风机在较宽频带上的噪声都较使用半开式导流罩时高;封闭式导流罩下风机出风湍流强度更高,衰减速度更快,噪声也更大;使用半开式导流罩时风机无论单独测试还是装机测试都可获取更低的噪声。同时,通过数值模拟和测试的方法分析半开式导流罩的宽度对冰箱冷凝风机出口的湍流强度以及冰箱噪声的影响,得到风机噪声最低时的导流罩宽度。冰箱冷凝风机在半开式导流罩下产生的湍流强度较低,相应的冰箱噪声也较低。     

导流罩对空调器室外机噪声的影响

为了明确导流罩对空调器室外机噪声的影响,利用数值模拟的方法对室外机内部气体流动进行了计算,研究了室外机出风口相对湍流强度的变化,分析了导流罩宽度、导流罩导弧对室外机噪声的影响。通过计算分析和试验验证,表明空调器室外机导流罩的宽度存在一个最佳值使室外机的噪声最小。同时,根据导流罩导弧对室外机噪声影响的规律设计出双导弧导流罩,经过试验验证分析,表明双导弧导流置与目前普遍使用的导流罩相比具有更好的气动性能,能进一步降低空调器室外要的噪声。     

厢式货车导流罩改进设计及气动优化

采用在圆弧板导流罩后缘处横向开缝的方法改善其减阻性能,并使用CFD方法完成了对加装该型导流罩的厢式货车的三维流场数值模拟及单/多目标气动优化.优化过程中,在给定货车行驶速度的前提下,以开缝位置、宽度为优化变量,将整车阻力作为优化目标进行单目标优化,并以此为基础,使用混合遗传算法,实现对阻力及气动噪声的多目标优化.研究表明,该方法可有效改善导流罩处绕流状况,能够在合理噪音范围内提供更优的减阻效果,具有一定的理论和实际应用价值.     

不同导流罩下高速电梯轿厢外缘气动特性分布规律的数值模拟

在高速电梯中,轿厢运动阻力剧增,各类涡流损失加剧,给系统经济性、安全性和舒适性带来隐患。文中为分析轿厢外缘流场的气动特性,建立计算流体力学数值模型,采用弹性光顺结合局部重构方法动态生成网格,对加装不同形状（三角形、梯形、椭圆形和车头形）导流罩的高速电梯轿厢进行了模拟。结果表明：加装导流罩可以有效改善流场分布,降低轿厢阻力系数;不同导流罩形状对电梯轿厢外缘的气动特性影响差异显著;与传统对称形导流罩相比,车头形导流罩的效果最好,其减阻比例高达80.21%。     

尾部减阻装置对厢式货车尾部流场的影响

为了降低某厢式货车的气动阻力,基于气动减阻机理设计了9种新型的尾部气动减阻装置。采用数值模拟的方法研究了尾部气动减阻装置对厢式货车尾部流场的影响,对比分析了安装9种尾部减阻装置的厢式货车的气动阻力系数、速度分布、压力分布及湍动能分布等流场特性,并对两种较好减阻装置的结构参数进行优化。研究结果表明:安装9种尾部减阻装置后整车气动阻力系数均有降低,降幅最大为7.96%,获得了较好的减阻效果。尾部减阻装置主要是通过减弱尾部涡流,增大尾部气压,从而来降低压差阻力。     

橫风作用下导流罩高度对受电弓气动特性影响

建立接触网-受电弓-导流罩-列车整体模型,基于分离涡模拟方法,研究了橫风作用时不同导流罩高度下受电弓非定常气动特性,分析了涡量、流线、气动荷载等的变化规律.结果表明:导流罩高度为100 mm时分离涡向橫风背风侧偏转显著,导流罩高度增加为400 mm时对受电弓下部杆件、车体连接处等作用增强;导流罩高度为200 mm时横风作用产生的绕流场偏转的效应明显得到改善,流场分布在纵向呈较好的对称性,其阻力系数的增幅远小于受电弓所受横向力的降幅,同时大幅降低了倾覆力矩和侧偏力矩,故在恶劣的风环境下采用200 mm高度的导流罩是可取的.研究结果对横风作用下导流罩高度对受电弓气动特性的影响研究具有重要意义.     

风区运行机车气动阻力研究

采用计算流体力学方法对机车气动阻力系数的影响因素进行了数值模拟。结果表明:在无挡风墙与土堤式挡风墙下,机车气动阻力随侧滑角的增加,先增大后减小;无挡风墙下,侧滑角β=0.43时,阻力达到最大;土堤式下,侧滑角β=0.52时,阻力达到最大;相同挡风墙高度下,土堤式下的气动阻力系数最大;相同运行环境下,当侧滑角小于0.6 rad时,土堤式的减阻效应比其他挡风墙差;当侧滑角在0.51~0.81 rad之间时,随着路堑深度的增加,机车的气动阻力系数越来越小;低路堑下,路堑坡角变化对阻力系数的影响与侧滑角有关。     

Experimental study on synthetic jet array for aerodynamic drag reduction of a simplified car

This paper describes an experimental parametric study of synthetic jet array actuation to reduce the aerodynamic drag of a threedimensional simplified car. By using two configurations of an Ahmed body with 25° and 35° slant angles, we performed wind tunnel tests under different conditions of synthetic jet array. Several parameters, namely, jet location, jet direction, jet momentum coefficient, jet driving frequency, and number and position of activated jets within the actuator array, were considered. The total aerodynamic drag coefficients were compared, and the rear wake flows were studied by using the data obtained from rear surface pressure distribution and flow visualization tests. Results of the parametric study show that the aerodynamic drag exhibits different behavior depending on the location of the jet for each slanted model. Jet direction, jet momentum coefficient, and jet driving frequency affect only the amount of change in the aerodynamic drag. The distribution of the activated jets also affects jet efficiency.     

Optimum nose shape of a front-rear symmetric train for the reduction of the total aerodynamic drag

For a high-speed train, the same power car is used as the first car and as the last car in a reverse direction simultaneously. Therefore, the previously optimized nose shape, considering only the first car position, is not well adopted in the last car position of a front-rear symmetric train in view of the aerodynamic drag. The three-dimensional nose shape optimization of a front-rear symmetric train is conducted to minimize the total aerodynamic drag of the entire train using CFD. The 3-D nose model is constructed by the vehicle modeling function with the optimized area distribution to minimize the micro-pressure wave. It is revealed that the total aerodynamic drag of the optimum shape for the entire train is reduced by 23.0% when compared to that of the conventionally optimized shape only for the first car of the symmetric train.     

安装实心轮胎对叉车性能的影响

轮胎是叉车的主要组成部分，多数叉车采用弹性较好的充气轮胎。以实心轮胎代替充气轮胎，叉车的动力性能和制动性能略有降低，但仍符合有关标准的要求；另外，可改善叉车的平稳性。     

赛车空气动力学套件设计与气动特性研究

FSAE赛车的空气动力学特性对其动力性、燃油经济性、操纵稳定性及制动性有重要影响.文中依据大赛规则设计了FSAE赛车空气动力学套件,基于CFD方法对比分析了3种不同参数的尾翼组合方案的气动特性,确定了最优的尾翼组合方案,根据最优方案的尾翼参数对前翼的参数进行了匹配;研究了有、无空气动力学套件的赛车的空气动力学特性,安装空气动力学套件后,赛车的气动升力系数由0.28下降到-1.19,气动阻力系数由0.44变为0.68,下压力显著增加;基于MATLAB对有、无空气动力学套件的赛车在特征赛道上的性能进行了计算,结果表明:赛车加装空气动力学套件后有效提高了过弯速度,推迟了刹车点,提高了圈速,有效提高了赛车的操纵稳定性和动力性.     

Investigation on aerodynamic drag of Korean high speed train (HEMU-430X) due to roof apparatus for electrical device

To explore the need for a roof apparatus for an electrical device, such as a pantograph cover or additional cover, the total aerodynamic drag of HEMU-430X, which is a high-speed train developed in South Korea with a maximum speed of more than 400 km/h, was experimentally analyzed using wind-tunnel testing. Experimental models were selected to a 1/20-scale, 5-car HEMU-430X model and three types of pantograph covers (A streamlined type and two wedge types), along with an additional cover. The experimental Reynolds numbers were 370000–620000. The aerodynamic drag of each car was simultaneously measured using load cells. First, the aerodynamic drag of each car without any roof apparatus was analyzed as the baseline model. Second, according to the variations in the three types of pantograph cover configurations, the aerodynamic drag of each car with pantograph covers was compared with the aerodynamic drag of the basic model. Third, the aerodynamic drag of each car with a pantograph cover and additional cover was compared with the results of the baseline model and baseline model with the pantograph cover. Finally, the aerodynamic drag due to the roof apparatus for an electrical device was investigated and analyzed.     

尾缘厚度对压气机叶栅气动性能的影响研究

针对不同尾缘厚度对压气机叶栅气动性能影响的问题,采用尾缘对称加厚的方法,在保证弦长、最大厚度、最大厚度相对位置、前缘半径、安装节距和安装角等参数不变的条件下,使尾缘厚度相对于弦长在0.1%~8.0%范围变化。根据Baldwin-Lomax模型建立了压气机叶栅二维湍流流动模型,并对模型近壁面进行了网格加密处理,通过隐式多重网格法加速计算的收敛,利用NUMECA软件,对叶型原型和对称加厚尾缘叶型的总压损失系数、叶型气流转折角和升阻比进行了数值计算。研究结果表明,尾缘厚度在一定范围内增大时,气流转折角减小,升阻比呈先增后降的趋势,而尾缘厚度较大时,推迟了叶型失速的出现,但尾迹损失和总压损失系数较大。