The Characteristics And Control Study Of Oil Liquid Sloshing In Automotive Fuel Tank Under Different Working Conditions

With the increasing awareness of energy crisis and environmental protection,automobile is gradually transforming from the mode of energy consumption to the mode of energy conservation and emission reduction,and governments and automotive OEM are increasingly demanding emission indexes for automobiles.In addition to automobile exhaust emissions,the emission performance of fuel system has been highly valued in recent years.To meet the higher emission index of fuel system,the characteristics of oil liquid sloshing,the volatilization characteristics of evaporative emissions based on the area of free oil liquid surface and the control technology of oil liquid sloshing have been explored and studied under different working conditions in this work.The main research contents are as follows:1.Theoretical study about oil liquid sloshing in fuel tank.The characteristics of oil liquid sloshing are briefly described under variable working conditions.The rectangular cavity model is established in inertial and motion coordinates,and the basic equations and boundary conditions are introduced in the process of oil liquid sloshing.Combining with the research content,the VOF simulation method is determined.The equivalent model of mass-damp-elastic about oil liquid sloshing and the basic equation of oil liquid horizontal sloshing under constant acceleration are described,and the equations of free oil liquid surface and hydraulic pressure distribution are obtained.2.The finite element models of three-dimensional fuel tank with oil liquid filled are created.Combining with the principle of accuracy and economy about model creation,the three-dimensional model of solid geometric and the finite element mesh of fuel tank are created separately by Pro/E and Hypermesh.The grid model data is shared with Fluent.The VOF method is used for the filling of oil liquid,the imposition of constraints and the setting of initial conditions in the model of three-dimensional fuel tank.At the same time,the simulation method is verified by different mesh sizes and different step time.Finally,the accuracy of the simulation data is verified by test.3.The study about the characteristics of oil liquid sloshing in fuel tank under the different influencing factors.The characteristics of oil liquid sloshing are studied from the views of fuel tank placement,fuel tank shape,the filling ratio of oil liquid,automobile acceleration,automobile acceleration duration and internal pressure of fuel tank based on different 3D finite element models of fuel tank.The pressure of oil liquid sloshing at the center point and on the centerline,the velocity of mass and volume are the main characteristic parameters of oil liquid sloshing under the same working condition.Comparing the parameters of oil liquid sloshing under the same working condition,it can be seen that fuel tank shape,the filling ratio of oil liquid,automobile acceleration and automobile acceleration duration have significant influence on the characteristics of oil liquid sloshing.The rectangular,elliptical and triangular fuel tanks are optimized respectively,and the heart-shaped fuel tank is proposed.It is found that the heart-shaped fuel tank is the best shape to suppress the pressure fluctuation of oil liquid sloshing at the center point and on the centerline.The larger the filling ratio of oil liquid is,the greater the pressure of oil liquid sloshing is,and the smaller the pressure fluctuation of oil liquid sloshing is.The greater automobile acceleration is,the greater the pressure of oil liquid sloshing is.The longer the automobile acceleration duration is,the greater the pressure of the oil liquid sloshing is,and the greater the pressure fluctuation of oil liquid sloshing is.4.The study about the characteristics of oil liquid sloshing in fuel tank with baffles of different structures.The characteristics of oil liquid sloshing are studied from the views of different baffle structure,size,shape,spacing,number and placement based on different 3D finite element models of fuel tank.The straight-line shape,arc shape,multi-segment line shape,multi-arc shape,corrugated shape and eccentric arc shape baffle is put forward in the process of research.Different placements include plane symmetry,translation symmetry and origin symmetry are proposed.Comparing the pressure data of oil liquid sloshing at the center point and on the center line under different factors and the pressure contours of oil liquid sloshing,it can be seen that the baffles with few holes,high baffles,corrugated baffles,small spacing baffles,double baffles and the baffles of central plane symmetry are helpful to suppress the pressure of oil liquid sloshing.5.The study about evaporative emission based on free oil liquid surface area in the process of oil liquid sloshing.The influence of fuel tank with different shapes,the filling ratio of oil liquid,baffle shapes and external factors on evaporative emission during oil liquid sloshing are studied under the same working condition.The concept of time-area value is proposed to the characteristic parameter of evaporative emissions.Comparing the data of free oil liquid surface area and time-area value under different working conditions,it can be seen that each baffle could attenuate the amplitude of free oil liquid surface area.Evaporative emission could be reduced under the combined action of inertia force and gravity.Heart-shaped fuel tank,less oil liquid filling ratio,corrugated baffles and small spacing baffles are the most conducive to reducing evaporative emission.6.The discussion of control technology about oil liquid sloshing in fuel tank.The technology schemes of passive and active control of oil liquid sloshing in fuel tank are described,and a new concept of active fuel tank is put forward.According to the passive control technology of oil liquid sloshing,control technology about mechanical energy absorbing and hydraulic,the device of oil liquid sloshing and energy recovery and reuse are invented.According to the active control technology of oil liquid sloshing,control technology about longitudinal and vertical rotation are invented.Among them,the active control technology of vertical rotation could satisfy the suppression of oil liquid sloshing in fuel tanks of different shape and different directions.Finally,the control technology and future development of fuel tank are prospected.