Performance Simulation And Optimization Of Small And Strengthen Gasoline Engine Transverse-flow Cooling System

In order to meet more and more stringent emission regulations,the degree of downsizing and boosting of engines improves,leading to gradual increase of the thermal load in the cylinder head bridge area,resulting in higher requirements about the performance of the engine cooling system.In this paper,a small downsizing gasoline engine with three cylinders is used as the research subject.This gasoline engine is top-down designed and meets the emission regulations based on this engine,research on the performance optimization of the transverse-flow cooling system is conducted with the one-dimensional and three-dimensional co-simulation and optimization projects are proposed.The laws about the structure optimization of the transverse-flow cooling jacket are summed up to provide reliable basis for the design and optimization of the new transverse-flow cooling system.The main contents are as follows:Firstly,according to the distribution of the water cooling system loop,one-dimensional cooling system model is built.The 1.0T engine cooling system is evaluated and the flow rate,pressure drop,basic parameters of transverse-flow cooling water jacket is obtained based on it.Secondly,the main research object concludes cylinder cooling and head water jacket.The three-dimensional CFD calculation model is established.According to one-dimensional cooling system calculation,the pressure,flow filed and heat transfer coefficients of transverse-flow cooling water jacket are analyzed.Results show that in the three-dimensional computation,pressure drop of the engine water jacket is 60.5kpa,which is higher than aim of cooling system.The preliminary design of cross flow of the water jacket pressure drop is large.Uneven distribution problems exist in the cylinder water jacket flow field.Moreover,in response to these problems,optimization projects are proposed,such as increasing the height of the inlet and outlet of the water jacket,arranging guide structures and adjusting the holes of gasket and water baffles and so on,aiming at reducing the pressure loss as much as possible with the improvement of the flow rate and transfer coefficient in critical areas of cylinder head and block water jacket.The last optimization projects pressure drop decrease to 41.6kpa.Based on the best optimization project,transverse-flow jacket CFD calculation is conducted and the flow-pressure drop curves are obtained,which is used as the boundary condition parameter in the one-dimensional computation.The optimized one-dimensional cooling system is calculated.Results show that pressure,flow rate and temperature of optimized transverse-flow cooling system meets the design requirements.Finally,first generation prototype of this gasoline engine is manufactured and tested.Test of this prototype is done based on the bench of gasoline engine.Results show that this prototype meets the design requirements of the power and economy performance,verifying the optimization design method of the transverse-flow cooling system in this paper.