Research On The Effect Of Lateral Wind And Longitudinal Spacing On Trucks In A Platoon

With the rapid development of economy of our country, the highway freight volume, highway freight turnover is on the rise and more and more trucks are coming into service. Related statistics show that the highway freight volume and highway freight turnover in our country had reached 35.45 billion tons and 6.47 trillion ton-km, in 2015, which account for the total quantity about 78.7% and 35.8%, respectively. Meanwhile, the amount of truck in road transport industry had reached 14.5336 million at the end of 2014, about 5.5% of national motor vehicle ownership. How to improve the fuel economy and reduce harmful exhaust emission of trucks is becoming the hot point in the research.Trucks travel in a platoon can effectively reduce the fuel consumption and increase the road capacity. Related studies have shown that with suitable longitudinal spacing in a platoon, trucks can averagely save fuel over 10%, which is helpful to enhance economic performance of transportation and has great application potential. However, most of the studies were conducted without considering the lateral wind. Undoubtly, it will produce a certain influence on the results. So, this paper shows the research on the effect of lateral wind and longitudinal spacing on trucks in a platoon.Lateral wind and longitudinal spacing has different effects on trucks in a platoon. In this paper, the simulation model with a proportion of 1:1 in reference to the Volvo truck was created by using Solidworks. For the purpose of simulation experiments go smoothly, the model was appropriately simplified, but retains the rearview mirror, fuel tanks and other parts which have large effects on air resistance of model. The XFlow, which is based on the Lattice Boltzmann method, was used as the numerical simulation software. XFlow can generate particle automatically, don’t need to mesh. Besides, it can realize efficient parallel, and the boundary condition processing is simple and the result of simulation is precise.Firstly, in order to analyze the effects of different lateral wind on the single truck, the simulation experiments were done which would provide comparison for the experiments of two trucks and three trucks platoon. The yaw angle of lateral wind variation range was 0 to 45 deg, the speed of truck was 25m/s. For the platoon who included two trucks or three trucks at speed 25m/s, the combined action of different longitudinal spacings and different lateral wind was studied. The longitudinal spacing of two trucks ranges from 0~30m, the yaw angle of lateral wind in the range of 0~20 deg. Relative to the two trucks platoon, the way of spacing changes between three trucks becomes more complicated. So, for the sake of exploring the effect of middle truck position on average drag coefficient of three trucks platoon, the simulation experiments were simulated without lateral wind, in which the spacing between trucks was unequal. Then on this basis, the effects of different longitudinal spacings and different lateral wind on three trucks platoon was simulated, and the longitudinal spacing ranges from 1~28m, the yaw angle of lateral wind in the range of 0~20 deg. According to the simulation results, the fuel-saving rate of trucks was also calculated.The calculated result show that the average oil-saving rate of two trucks and three trucks platoon were 8.93% and 15.01% respectively, which is obvious for truck. Then the mechanism of aerodynamic drag of truck and the rule of drag coefficient of trucks in platoon was analysed from velocity field and pressure field, which may provide the theoretical basis for later related research.