Research Of Coupled Simulation Method Of Engine Cooling Water Jacket

Nowadays，with the engine development towards high power and high speed, thethermal load is gradually increased，which thermal intensity have greatly affected thedurability, reliability and economy of the engine. Therefore, people more and more payattention to the study of the engine heat transfer. Test and simulation methods were used toresearch the topic of heat transfer in water jacket of a four-cylinder turbocharged gasolineengine. The coupled method of one-dimensional simulation and three-dimensional numericalcalculation was used to solve the coolant flow field and temperature field in the, water jacketand the temperature field of engine block. The engine cooling performance and thermal loadwas evaluated. The coupled simulation method which is suitable for the research wasstudied.Before solving the temperature field, according to the experimental prototype geometricstructure and parameters, the intake and exhaust system, fuel supply system, turbo system,cylinder and crankcase modules were set up using GT-POWER software, the valve timing,combustion model and heat transfer model parameters were set, then a complete virtualengine model was built up. With debugging and solving the model, The engine performanceparameters were gotten in the postprocessing. The one-dimensional model. was verified bythe test data which were gotten from the engine calibration test of full load characteristics.Simulation results were in good agreements with experiment value. On this basis, gastemperature and heat transfer coefficient parameters in cylinder were brought out as heattransfer boundary conditions for solving3D temperature field. The data which would be setout to3D simulation were achieved and implemental.The test platform of engine temperature field was established. The selection of thetemperature measurement instruments and seal methods were discussed. After that, the testmethod and the position of measurement points were determined. The test points on cylinderblock were arranged on the cylinder liner wall both on the intake and exhaust sides and inthe middle zone of the connection between the two cylinders. The test points on cylinder head were arranged between two cylinders, and in the bridge zone between the intake andexhaust valve of each cylinder. The temperature values of the test points were measuredwhen the engine was under the full-load characteristics condition, load characteristicscondition and idle condition respectively. The temperature field distribution characteristicsand heat load value of the heated parts were gotten under different working conditions. Thecooling capacity of the water jacket was estimated to be good and the thermal load of theheated parts met the design requirements. Test results provided a basis for verifying thecoupled simulation method.Numerical simulation method of solid-liquid conjugate heat transfer was used to solvethe temperature field of the engine. Using per-processing software ANSYS ICEM CFD toget the grid of solving region, the division-assembly methods was applied. Liquid areas andsolid areas were defined in different cell sizes, in which the key-part grids should beincreased the density. One layer of prism grid was set off as the boundary layer in the fluidzone near the wall to increase the accuracy. The whole grid was input into FLUENTsoftware and the boundary conditions to solve the flow field and temperature field were setup. Finally, the flow field and the temperature field were solved. The temperature fielddistributions were gotten under the maximum torque speed and the rated speed full-loadcondition. The analysis on the results showed that the cooling system design was reasonableand the heat loads of the parts were permitted. By comparing the calculate results with thetest data, they were matched well and the deviation was small.Through the research of experiment and simulation calculation, the cooling ability ofthis engine was found good and the heat load results achieved the design requirements.Using the test data to verify the simulation calculation values, the deviation of them wassmall, which proved the coupled simulation method was practicable and accurate.