| The car cooling system is an important auxiliary system in the whole vehicle.It is one of the systems to ensure the car can run stably.It must ensure that the engine or other components are in a suitable temperature range,and whether the whole vehicle can operate efficiently and economically.Critical impact.However,with the increasing engine power,the application of new technology makes more and more parts need to be arranged in the engine compartment.The thermal load in the engine compartment is increasing and the installation space is increasingly compact.How to change the layout conditions and reasonable Under the premise of controlling energy consumption,improving the heat dissipation efficiency of the radiator is a hot spot in the field of radiator research.In this paper,the combination of numerical simulation and experiment is used to systematically and deeply discuss the flow and heat transfer of a certain SUV model radiator and its front-end cooling module,aiming at not changing the front-end cooling module and radiator arrangement.Under the premise,the heat dissipation efficiency of the radiator of the vehicle is enhanced,and the temperature uniformity of the flat tube of the radiator is improved.The main work of the thesis is as follows:(1)The mathematical model for establishing the louvered radiator includes: heat-dissipating flat tube,water chamber,main board,and cover plate.Explain the theoretical basis for the simplification of the louver fins by the theory of porous media.According to the parameters of the louver fins,the values of the fins are numerically determined.Calculation and simplification;put the radiator assembly into the front-end cooling module(condenser,intercooler,fan assembly)and radiator bracket,bumper,front anti-collision beam,upper and lower air intake grille,body,tire Analyze the heat transfer and flow characteristics of the radiator in high-speed climbing and low-speed and heavy-load conditions in the real vehicle operating environment;(2)The simulation results of the model show that: 1 due to the structure of the vehicle body and the arrangement of the front-end cooling module,the airflow velocity difference between the engine compartment and the radiator bracket is large,and the airflow leaks rapidly after the air flows through the intercooler and the condenser;Under high-speed conditions,the external flow velocity distribution of the entire front-end cooling module is more evenly distributed.The highest external flow velocity is at the outer edge of the fan blade under low-speed conditions;2 the higher air intake under high-speed climbing conditions makes the radiator external The air flow field is more uniform.The fan arrangement under low speed conditions has a greater impact on the heat dissipation performance of the radiator than the high speed condition;the coolant flow distribution in the radiator flat tube is not uniform,and the coolant flow rate near the lower flat tube is larger than the upper flat tube,low speed.And the high-speed working condition reaches the peak flow at the flat tube 50;the unevenness of the external air flow field and the internal coolant flow field of the radiator causes the temperature distribution on the outer surface of the radiator flat tube to be uneven,low-speed and high-speed working conditions.The lower maximum temperature area appears in the lower right corner of the radiator,the low speed working condition reaches 117 ° C,and the high speed working condition reaches 103 ° C;(3)Conducting a real vehicle test on an SUV in an environmental simulation test room.The test results show that the temperature distribution of the radiator measuring point is not uniform,and it is more obvious under low speed and large load conditions.The highest measuring point temperature and the lowest measuring point The temperature difference is about 14 °C;at the same time,the maximum temperature of the radiator in the low-speed working condition fluctuates due to the cut-off and recovery of the air-conditioner,and the temperature of the radiator in the high-speed working condition is stable;the comparison between the test point data and the simulated measuring point data shows the temperature trend of the measuring point Basically,the simulation error is between-5% and 3%,and the model can be considered as a substitute for the experiment for subsequent optimization studies;(4)Explain the principle of field synergy.The field synergy principle is used to analyze the temperature field and air velocity field of the radiator coolant.It is found by the formula that the heat dissipation efficiency of the radiator depends not only on the air temperature and flow rate,but also on the surface temperature of the radiator flat tube and the air between the flat tubes.The degree of synergy of speed;the heat sink studied in this paper is discretely coupled to the flat tube temperature-coolant flow-air flow surface,and the relationship between the surface temperature of the flat tube of the radiator,the flow rate of the coolant in the flat tube and the air flow between the flat tubes is found in the air.When the flow rate is the same,the temperature of the flat tube increases as the flow rate of the coolant increases.For a flat tube of the same flow rate,the temperature of the line with a large air flow rate is low;(5)Under the premise that the cooling module at the front end of the radiator is not modified,the radiator is optimized to improve the heat dissipation efficiency of the radiator.The optimization scheme is as follows:(1)Optimize the structure inside the radiator water chamber,specifically distribute the coolant flow between the flat tubes,distribute more coolant to the area where the external air flow rate is large;2 adjust the fan position,try to make more Air passes through the area where the heat sink temperature is high.Finally,after optimization,the surface temperature uniformity of the radiator flat tube is improved,and the heat dissipation efficiency of the radiator is enhanced. |
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