Underhood Thermal Analysis And Improvement Of A Bus With Rear Engine Compartment

With the development of the automobile industry, the increasing requirements ofthe automotive power, economy and comfort made the engine power increased. Theengine components number increasing made the cabin space is more crowded whichgive the engine compartment cooling a serious challenge. In this p aper, according to apassenger car cooling water boil and cabin overheating with low-speed and heavyload in hot weather, we have a study in temperature and flow field for enginecompartment using the Computational Fluid Dynamics method, then found out theoverheating zones and the reasons causing the cabin overheated. Then proposed someimprovements and solve cabin overheating problem successfully. The main work inthis paper includes:Firstly, we created engine compartments and passenger car CAD model usi ngthree-dimensional modeling software. Then use the commercial software meshing andcalculations. Before the calculation, we should calibration the CFD model withexperimental data to ensure reliability of the CFD model. Then for the worstconditions of the passenger car we have a simulation of the cabin temperature fieldand flow field. According to the temperature and velocity field in the cabin, we findout the reasons causing the cabin overheated and propose three improvements: A) adda guiding device in the cabin stairs; B) increase the open area on the top of back cover;C) remove the grill on the back cover.Secondly, according to the three improvements we have made seven differentcombinations. They are A, B, C, AB, AC, BC and ABC. After that we m odified theCAD models and did a simulation for each combination. By comparing thetemperature field of the improved model and evaluate the improvement program’seffect using evaluation methods. Final we get the best improvement program.In a word, the research work of the passenger cabin thermal management canprovide some reference suggestions for the passenger car design.