Research On The Optimal Matching Of Cooling And Dust In Heavy Commercial Vehicle Underhood

Because the power of commercial vehicles is increasing now,the temperature in the engine cabin also increases with the increase,in order to meet the temperature requirements in the engine room.Need to choose large diameter,large air volume fan.On the other hand,the engine cabin design is becoming more and more complex,and the arrangement becomes more compact,which makes the flow resistance of the cooling air in the engine room become larger,which causes the fan outlet air not to bypass the engine well along the axial direction,but to spread directly to the rear of the engine around,and the part leading to the ground will cause dust.Dust is easy to float in the air to cause environmental pollution,when dust particles are sucked into the radiator,resulting in a decrease in heat dissipation capacity.Therefore,it is of great practical significance and economic benefit to solve the problem of heat dissipation and dust raising in engine cabin of heavy commercial vehicle.Based on aerodynamics theory and DPM technology,this paper studies a commercial vehicle with severe dust raising,and improves the structure of engine cabin to optimize the matching of dust and heat dissipation by analyzing and comparing the flow field and temperature field in engine cabin and the number of raised particles.First of all,the force analysis of the particles on the ground is needed,and the influence of cooling air flow on the particles is mainly considered in this paper.It is mainly affected by gravity,air drag force and other secondary lift force on dust particles,and the basic theory of computational fluid dynamics includes basic control equations,turbulence models and so on.After that,the dust degree of commercial vehicles is determined by experiments,and the dust simulation test is carried out on the commercial vehicles with serious dust,and the minimum speed of the fan leading to dust is measured;when the fan speed reaches 1300r/min,it can already produce serious dust.When the fan speed is 1300 r/min,the maximum wind speed on the ground is 5.25 m/s.Secondly,the whole vehicle is simplified and meshed;the boundary conditions of the internal flow field are set and the parameters of the DPM and solver are set.This fan speed is simulated to capture the wind speed at the bottom of the vehicle to form a cloud map,comparing the test results with the simulation results,the trend of the bottom wind speed and the maximum wind speed are basically consistent with the experimental test.Through the simulation calculation,the details and performance parameters of the engine cabin flow field are obtained,such as the bottom wind speed cloud map,the flow field trajectory map,the cabin pressure cloud map,the velocity vector and the intake mass flow rate of the radiator.The structure and layout of the parts in the engine cabin are improved by comparing the flow field details and performance parameters in the engine cabin,by increasing the distance from the fan to the engine 60 mm、 extending the air retaining ring 50 mm and adding the 10 degree flow guide plate the left and front sides of the engine oil bottom shell.The optimization not only ensures the heat dissipation performance in engine cabin,but also optimizes the dust control.Finally,the optimized effect is verified by experiments.By driving on the dusty road surface,the dust before and after optimization is compared,and the dust caused by the optimized cooling air flow is obviously improved.The heat balance experiment was carried out in the engine cabin,and the surface temperature of the parts in the engine room was not increased compared with the original state after optimization.Experimental surface,by changing the structure and layout of engine room parts,effectively solve the fan cooling air flow caused by the dust problem and the engine room heat dissipation problem matching research.