A Study On Underhood Thermal Analysis Of Vehicle Platooning

Automobile industry has made great progress under the bloom of economy these years.The increasement of automobile lead to serious issues,such as energy crisis,emission pollution and traffic congestion.Platooning is a driving mode of Intelligent Transportation System,in this mode,multiple vehicles form a platoon of different driving distance,the vehicles can be controlled by the computer and communication equipment through speed sensor and position sensor.Platooning can not only improve the road capacity,reduce road congestion,but also reduce the aerodynamic force of the vehicle,so as to reduce the fuel consumption and exhuast emission.In this paper,numerical simulation is used to study the underhood thermal character of platooning.In this paper,a 1:1 truck geometric model is adopted,details and some accessories is simplified.A simulation on point of maximum torque is carried out,then a road test is carried out to validate the simulation.After the validating,the paper focus on the study of platooning.Assuming the platoon is running at a speed of 90km/h.First,a single truck simulation is finished to be compared with the truck in the platoon.The velocity field and pressure field of the single truck is analyzed.The parameters such as cooling air flux and coolant temperature of the coolant are monitored for comparison with the truck in the platoon.Then,the underhood thermal characteristic of the following truck in two truck platoon is studied.The study found that,compared with single truck driving,when traveling in a platoon,the aerodynamic force of both front and following truck is reduced,and the aerodynamic force of the following truck is always smaller than that of the front vehicle,which affect the fuel consumption and heat released by the cooling system.The flux of the cooling air of the following truck also decrease compare with single truck.The temperature in underhood of the following truck and the temperature of the coolant are also higher than that of the single truck,and the influence is greater when the distance is less than 0.4 times the length of the truck.Finally,the underhood thermal characteristic of the following trucks in three truck platoon is studied.The speed and truck distance are the same to the two truck platoon.The study focus on the aerodynamic force,the cooling air and the temperature change of the following truck in platoon.The aerodynamic force change of three truck platoon is more complex than a two truck platoon.The flux of the cooling air of the following truck decrease compare with single truck.The flux of the cooling air of the middle truck is slightly larger than that of the rear car.With the increase of driving distance,both the flux of middle truck and the rear truck show the trend of decreasing first and then stabilizing.The study find the underhood temperature and coolant temperature of following truck increase in a platoon,which has a greater influence when the driving distance is less than 0.6 times the truck length.The study indicate that the temperature of the following truck is always higher than that of the single truck,and a shorter driving distance leads to a higher temperature,especially when the distance is shorter than 0.4 times the truck length,the coolant may reach its boiling point.Consequently,when setting a truck platoon,a shorter distance means a smaller value of fuel consumption,but as the truck getting closer to each other,such as a distance shorter than0.4 times of length,both the fuel consumption and the underhood environment should be considered carefully.