Parametric Optimization of Wheel Spoke Structure for Drag Reduction of an Ahmed Body

The wheels have a considerable influence on the aerodynamic properties and can contribute up to 25%of the total drag on modern vehicles.In this study,the effect of the wheel spoke structure on the aerodynamic performance of the isolated wheel is investigated.Subsequently,the 35°Ahmed body with an optimized spoke structure is used to analyze the flow behavior and the mechanism of drag reduction.The Fluent software is employed for this investigation,with an inlet velocity of 40 m/s.The accuracy of the numerical study is validated by comparing it with experimental results obtained from the classical Ahmed model.To gain a clearer understanding of the effects of the wheel spoke parameters on the aerodynamics of both the wheel and Ahmedmodel,and five design variables are proposed:the fillet angleα,the inside arc radius R1,the outside radius R2,and the same length of the chord L1 and L2.These variables characterize the wheel spoke structure.The Optimal Latin Hypercube designmethod is utilized to conduct the experimental design.Based on the simulation results of various wheel spoke designs,the Kriging model and the adaptive simulated annealing algorithm is selected to optimize the design parameters.The objective is to achieve the best combination for maximum drag reduction.It is indicated that the optimized spoke structure resulted in amaximum drag reduction of 5.7%and 4.7%for the drag coefficient of the isolated wheel and Ahmed body,respectively.The drag reduction is primarily attributed to changes in the flow state around the wheel,which suppressed separation bubbles.Additionally,it influenced the boundary layer thickness around the car body and reduced the turbulent kinetic energy in the wake flow.These effects collectively contributed to the observed drag reduction.

The Effect of Lateral Offset Distance on the Aerodynamics and Fuel Economy of Vehicle Queues

The vehicle industry is always in search of breakthrough energy-saving and emission-reduction technologies.In recent years,vehicle intelligence has progressed considerably,and researchers are currently trying to take advantage of these developments.Here we consider the case of many vehicles forming a queue,i.e.,vehicles traveling at a predetermined speed and distance apart.While the majority of existing studies on this subject have focused on the influence of the longitudinal vehicle spacing,vehicle speed,and the number of vehicles on aerodynamic drag and fuel economy,this study considers the lateral offset distance of the vehicle queue.The group fuel consumption savings rate is calculated and analyzed.As also demonstrated by experimental results,some aerodynamic benefits exist.Moreover,the fuel consumption saving rate of the vehicle queue decreases as the lateral offset distance increases.

应用模型的智能轮胎垂向力估计算法

垂向力在车辆控制中起着重要作用,也是智能轮胎中的重要参数。本文中提出了一种传感器和物理模型结合的垂向力估计算法。根据加速度曲线特征分析了内衬层加速度信号与轮胎接触角的关系,通过有限元仿真验证了接触角估计算法的可行性;使用环模型建立接触角-垂向力的关系,利用轮胎试验验证关系的准确性。利用有限元模拟智能轮胎,比较垂向力的预测值与仿真值,结果表明使用传感器与轮胎模型结合的方法可以快速准确地进行垂向力估计。

Aerodynamic Characteristics of Isolated Loaded Tires with Different Tread Patterns: Experiment and Simulation

The current research of tire aerodynamics mainly focus on the isolated and simplified tread tire.Compared with the real complex pattern tire,the tread pattern structure and deformed profile of a loaded tire has a greatly influence on tire aerodynamic drag.However,the mechanisms of the isolated loaded tires with different tread patterns effects on the aerodynamic drag are subjects worthy of discussion.The purpose of this study is to experimentally and compu-tationally investigate the aerodynamic characteristics of three tires 185/65 R14 with different patterns under loaded.A wind tunnel test model was first established using three-dimensional(3D)printing with a ratio of 1:1,and the pres-sure coefficients C_(p) of the three tires with different patterns are measured.The paper then conducted computational fluid dynamics(CFD)simulations for analyzing the pressure and flow characteristics.The accuracy of CFD simulation is verified by comparing the simulation results with the test results of pressure coefficients C_(p),and they are of good consistency.While,the general analysis of pressure coefficients C_(p) results of the three tires indicates high-pressure area on the windward surface,and occurrence of low-pressure area on the leeward surface,the pressure coefficients C_(p) of all three tires decreased firstly and then increased along in the air flow direction.The authors finally analyzed the effect of tread patterns on the flow field around the tire and revealed the differences between flow characteristics and aerodynamic drag.The results show that,angle of tire lateral groove has great effect on the flow field characteristics such that;the more the angle of lateral groove agrees with the air flow direction,the less the flow separation and flow vortices,and a minimum observable aerodynamic drag.The research provides a guidance for the design of low aerodynamic drag tires,and helps to illustrate the impact of tire aerodynamics on the car body in the future.

用有限元模拟分析优化宽基轮胎的成型工艺和设计

宽基轮胎是近年来应用和发展较快的一种新型轮胎。在载重汽车用宽基轮胎替代并装双胎的普通轮胎,具有改善车辆与地面的附着性和耐磨性等多项性能的潜在优势。但是,宽基轮胎在成型制造过程中,很容易出现胎面变形和应力分布不均匀的现象。本文研究的目的是应用数值分析技术仿真模拟宽基载重汽车充气轮胎的成型制造过程,进而指导优化轮胎的施工设计。首先,应用有限元分析技术模拟385/55R22.5规格轮胎的成型制造过程,包括四个阶段:分别是成型主鼓部件贴合、辅助成型鼓部件贴合、半成品胎坯成型和最后的胶囊硫化机硫化定型过程。其次,为了解决435/50R19.5规格轮胎生产中存在的实际轮胎结构与理论设计的轮胎结构在材料分布方面的差别,根据轮胎施工设计仿真模型的分析结果,提出曲面鼓成型半成品胎坯的方法,并且确定了曲面鼓的设计参数。在本文中,我们给出了收集轮胎材料的方法、测试过程、分析方法、试验结果和相关数据的统计。最后,通过试验检测结果对仿真模拟模型的准确性进行了验证。