Research And Optimization Design Of The Intake Port For Gasoline Based On CFD

In recent years,with environmental and energy issues increasingly prominent,energy conservation and emission reduction have become the focus of today,reducing vehicle fuel consumption and improving engine thermal efficiency have become the focus of major automotive manufacturers.A lot of research results shows,the complete combustion of the air-fuel mixture in the engine has a decisive influence on the thermal efficiency of the engine.Therefore,improving the combustion quality of the air-fuel mixture in the engine is the main way to improve the thermal efficiency of the engine.Engine inlet ports is an important part of the engine intake system,its design affects the intake air charge and the formation of combustible mixture of the engine,the performance of the inlet ports will affect the propagation of flame combustion and the formation of oil-gas mixture in the engine.Therefore,an excellent engine intake ports design will effectively improve the engine's fuel economy.The main research content is as follows:Based on CFD,the finite element model of an intake port of a gasoline engine was established,through the ports steady flow test,the accuracy of the established three-dimensional steady-state calculation model was verified,and the relationship among ports evaluation parameters.At the same time,partial load tests were performed to verify the effect of the tumble flow ratio on fuel economy.The results shows,the established three-dimensional steady calculation model can accurately simulate the flow coefficient and the tumble ratio by numerical simulation method,the simulation results provide the basis for the optimal design of the engine intake,the increase of the tumble ratio can improve the fuel economy of the engine,but at the same time it will also have a certain influence on the flow coefficient.Analysis of geometric parameters affecting air flow in cylinder based on CFD.Among them,the deflection angle influences the turbulent kinetic energy of the airflow in the cylinder.As the deflection angle increases,due to the guiding effect,the flow in the direction of the exhaust valve at the valve disc is increased,thereby increasing the tumble ratio.Increasing the throat angle can reduce the loss of momentum at the throat and improve the circulation performance,but it also weakens the guiding ability of the throat and the combustion chamber and causes the air flow to “bump” at the cylinder wall.The choice of airway deflection angle and throat angle has a great influence on the flow state of the gas entering the cylinder.Therefore,this paper mainly optimizes the ports deflection angle ? and throat angle ?.Finding the law through the optimization of the deflection angle ? and throat angle ? in the three-dimensional steady-state calculation model,there is a positive correlation between deflection angle and tumble flow ratio;throat angle is negatively correlated with tumble ratio within a certain range.While increasing the tumble flow ratio,the flow coefficient will decrease accordingly,thereby affecting the intake air charge and reducing the engine power output.The goal of this paper is to optimize the air intake based on the EMO,design the parameters of the deflection angle and throat angle,the decrease of the flow coefficient is reduced as much as possible or even unchanged while increasing the tumble ratio.In this paper,Latin hypercube sampling and response surface methodology(RSM)are used to fit the approximate model of the engine inlet,application NSGA-II to optimize deflection angle ? and throat angle ?,determine the optimal design by comparing the flow coefficient and tumble ratio.Research shows:The optimized intake ports can increase the tumble ratio while keeping the flow coefficient unchanged.The results of an optimized design to improve the tumble ratio in the end,the optimization results in this paper provide some ideas for improving the fuel economy of the engine.