Research Of Internal Flow Characteristics Of Underhood For Heavy-duty Truck Based On Layout Of Cooling Modules

With the development of the modern automotive technology，the work load of theengine is getting stronger day by day.The problem about the overheat of the enginecompartment is getting worse. The characteristic of the air flow in the engine’s compartmentwas closely related to the resistance of the air flow and heat emission of the enginecompartment. This article determines on the CFD method to make a simulation of a heavytruck’s flow field characteristics.This article focus on cooling module position change of condenser, intercooler, watertank, radiator and fan. which affect on air flow and cooling of the engine compartment. Thisarticle has made an simplification of a heavy truck’s complicated geometric model. In thepre-processing software Hypermesh, a high quality grids has been divided. And also, thedivision, the solving and the Post-processing of the Calculation results is finished under thestar-ccm+,which is a general heat flow analysis program. During the process of thesimulation, the condenser, the intercooler and the radiator used porous media. The fan iscalculated and analyzed under the MRF Reference Coordinate System. The flow region ofthe simulation model includes truck external air flow field coupled with the enginecompartment air flow field and the water tank radiator which is full of cooling water. The airflow field and fluid flow field are coupled with interface.This article study about the simulation when the truck is climbing under a high ambienttemperature of40℃and when the engine has a maximum torque force. Under thesecircumstances,the truck’s speed is low, And the engine is prone to be overheated. After thecalculation of the original model truck, the speed and the temperature distribution which isdescribe the flow Situation of the engine compartment has been got.Based on the processingresults，we analyzed the engine compartment’s internal flow structure,characteristic of the flow and distribution pattern of the temperature. The temperature of the radiator’s outletwater pipe reached109.02℃.The radiator is overheated. In this article, analysis has beencarried out to find out if the arrangement of the cooling modules has any effect on the flowand temperature field.Several possible improvements of the cooling modules arrangementhave been brought out. They also use the same boundary conditions to make analysis.Three improving cases have been brought out to change the arrangement of the coolingmodules, which are in the original truck model. The3rd case contains5small solutions.Each of the cases is analyzed and the results are compared. Through the results, we are goingto see whether the change of the cooling modules has any effect on the flow structure. Andalso, we compared the temperature field distribution under these cases. We monitored thecooling air flow which flow through the radiator and the outlet water pipe’s temperature.Theresult shows the1st case and the3rd case has a good performance in heat elimination.However, the2nd solution’s arrangement is not conducive to heat elimination. Aftercomparing the best arrangement of the cooling modules in the1st and3rd case, the coolingair flow increase by6.7percent compared with the original model.At last,we analyze the radiator’s cooling performance under the condition when theengine is working at the maximum torque. We get the inlet and outlet water pipe temperaturevariations on a graph as a function of time.We use the average value as the balancedpoint.And we compare the value with the the simulation value. The relative error is9.5%.Itis accepted in engineering.