Numerical Simulation Of Wind-induced Vibration Characteristics Of Side Skirts Of Trucks

With the rapid development of the expressway and the continuous increase on the speed of automobiles,trucks have become the main means of transporting goods between cities.However,the aerodynamic problems that accompany them have become increasingly prominent.When trucks are driven by natural wind In the case of complex crosswinds or artificial wind conditions resulting from intricate road conditions,the skirts located on both sides of the truck container are subjected to alternating loads,and the skirt is connected to the container due to the long distance traveled by the truck.At the same time,it is easy to produce fatigue damage and threaten the safety of driving.Therefore,it is of great significance to analyze and study the effect of the aerodynamic load acting on the truck skirt under different working conditions and the structural response of the skirt.The causes of the skirt vibration include uneven road surface,mechanical vibration of the automobile itself,and wind-induced vibration.The cyclic load caused by wind-induced vibration is the main cause of fatigue damage at the skirt joint.This paper proposes a comparative analysis method of bidirectional coupling and unidirectional coupling to study the wind-induced vibration of the skirt under different working conditions.The research contents include the basic research on the wind-induced vibration of panel,the analysis of wind-induced vibration characteristics of the skirt with or without side wind,and influence of different operating parameters on wind-induced vibration characteristics of skirts.This paper uses Fluent to calculate the flow field and Transient Structure to calculate the solid field.Both of them realize the coupling and co-simulation data exchange under the System Coupling module.Firstly,the two-dimensional cylinder is selected as the basic model to study the flow mechanism of the cylinder flow at different Reynolds numbers.It is found that in the subcritical region,with the increase of the Reynolds number,the wake flow characteristics around the cylinder become more and more unstable.At the same time,regular vortex shedding will also present a corresponding single vortex shedding frequency.Afterwards,a simple fluid-structure coupled numerical simulation was performed by means of one-way coupling and twoway coupling.The calculation results show that when the fluid flows through the solid surface of the bluff body,the boundary layer separates,resulting in the periodic alternating detachment of vortices on both sides of the bluff body.Therefore,the flat plate at the wake is continuously affected by the vortex shedding,and pressure difference between the two sides of the flat plate generates a pulsation load,resulting in the solid structure being affected by the alternation.Secondly,based on the establishment of different fluid domains under different lateral wind conditions and the setting of different boundary conditions,the numerical simulation analysis of the truck skirt in the presence or absence of cross wind conditions is carried out.Under the condition of no side wind,this paper compares the flow field structure,the pressure distribution on the skirt surface and the displacement response of the skirt structure obtained by the one-way coupling and bidirectional coupling methods to summarize the reasons for the differences between the two methods and find the best numerical solution method for fluidsolid coupling.Under the strong side wind conditions,this paper analysis the wind-induced vibration of truck skirt based on the change of flow field and response of solid structure by analyzing the structure of the flow field inside and outside the skirt,the surface pressure distributions on the windward side and the leeward side which is combined with the results of the modal analysis of the skirt and the displacement response of the skirt structure.At last,this paper studies the influence of different operating conditions on the windinduced vibration characteristics of the skirt.Under the condition of no side wind,the changes of the distribution of the pressure on the skirt and the response of the structure under different driving speeds were investigated,and the influence of the driving speed of the truck on the wind-induced vibration characteristics of the skirt was analyzed.For strong side wind driving conditions,the lateral wind speed is mainly changed.The flow field under three working conditions is numerically simulated to obtain the influence of the lateral wind speed on the wind-induced vibration of the skirt.This paper compares the influence of driving speed and lateral wind speed on wind-induced vibration characteristics of skirt wind.The results show that under no-wind conditions,the amplitude of the skirt doubles with the increase of the vehicle speed,which means that the vortex shedding generated by the protrusions passing through the bottom of the truck has little effect on the skirt vibration and is mainly affected by the strength of the wind field.Under the strong side wind conditions,the low frequency amplitude of the skirt structure is an important index to measure the size of the skirt deformation.The change of the speed of the side wind has greater influence on the deformation of the skirt structure than the change of the speed of the skirt.