| The geometric parameters of automotive cooling-system components play a vital rolein engine cooling. As one of the most important cooling components, the parameters ofcooling fan will affect the fluid field of the engine cabin, thereby affect the performance ofthe engine cooling. In order to ensure the engine in the best operation condition, higherrequirements to the performance of cooling fan are put forward by automobile enterprises.Fan characteristic got from the traditional duct experiment has great difference with thatgot from real situation, due to the surroundings of the fan is different. Generally, evaluationof the performance of cooling fan will be more accurate and authentic by investigating thefluid field characteristics of cooling fan with different parameters working in the enginecabin.Based on the consideration above, this thesis mainly use numerical simulation methodto research the characteristics of cooling fan with different parameters in a simplified heavytruck. The impact of various geometry parameters of the cooling fan on its coolingperformance, flow field and temperature field of engine cabin are analyzed. Here, coolingfans with different number of fan blade and rotating speed are mainly researched. Thecooling fan included by heavy truck is first simulated (the number of fan blade is9, rotatingspeed is1400rpm). In the process of simulation, Hyperworks is used for previous surfacemesh generation, and STAR-CCM+is used for volumetric mesh generation, establishingthe simulation models, numerical calculation and post-processing. Particularly, during thenumerical calculation porous medium model is adopted to simulate condenser, intercoolerand radiator. As the major research object, cooling fan is simulated by MRF model.In order to analysis the influence of the engine cooling fan of heavy-duty truck on thetruck cabin flow field characteristics and thermal performance much more effectively, atthe time of calculation, extreme operating condition is selected as computational condition.Therefor, in the numerical calculation, ambient temperature is set as40℃whichis the wretched temperature supported by study vehicle under maximum torque workingcondition. Besides, other thermal boundary condition is set by experiences.During the experiment, the water temperature of the inlet water pipe and out waterpipe of the radiator is monitored through the temperature sensor and data collector.Numerical simulation with the same calculation condition as the experiment is done.Comparing the water temperature got from the simulation with that of experiment, it can befound the error between simulation and experiment is8.3%.On the basis of analyses of simulation results and experimental verification, theimpact of cooling fans with different number of fan blade and rotating speed on the fluidfield of engine cabin in heavy duty truck are mainly studied. The study details:(1) The impact of cooling fan with different fan blade number on the fluid field ofengine cabin. Cooling fans with number varying from7to10is simulated respectively, inthe simulation, the study truck is under maximum torque working condition, and rotatingspeed of cooling fan is fixed at1400rpm. The optimal fan blade number is obtained afterdiscussing the influence of fan blade number on fluid field and heat transfer of engine cabinthrough analyzing static pressure distribution of the cooling fan, vorticity distribution andvelocity distribution in Y=0section.(2) The impact of cooling fan with different rotating speed on the fluid field of enginecabin.Cooling fan with different rotating speed varying from1400rpm to1900rpm iscalculated, during the calculation, the fan blade number of cooling fan is fixed at9which isthe optimal number obtained from the previous calculation.In order to achieve moreconvincing analysis result, aforementioned calculation is calculated again in which theheavy truck is under idling condition. The optimal rotating speed of cooling fan is gainedfrom the simulation result. To gain the optimal rotating speed of cooling fan, comparativeanalyses of velocity distributions and temperature distributions in Y=0section of thesimulations truck under maximum torque working condition and idle condition are performed. Furthermore, the power consumed by the cooling fan is also considered at thetime determining the best rotating speed of the cooling fan.In conclusion, the numerical simulation method about the engine cabin of heavy dutytruck adopted here will provide an effective research method for truck factories to designand match appropriate cooling fan. Besides, the flow field simulation results, data andconclusions in this thesis can offer sufficient support for data and adequate theoretical basisfor truck factories to design and match appropriate cooling fan. |
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