Study On Control Of Fuel Sloshing In Fuel Tank About A Passenger Vehicle

With the application of low-noise engines and low-noise transmission systems,the fuel tank sloshing noise,which is one of the sources of noise inside the vehicle,has an increasingly prominent influence on the ride comfort of the vehicle.In this paper,the problem of fuel sloshing noise of a newly designed passenger car fuel tank is studied.The subjective evaluation is used to evaluate the noise caused by the fuel sloshing in the fuel tank of the new passenger car and benchmarking vehicle.And the driving condition and fuel tank filling level of the vehicle with the most serious fuel sloshing noise are determined.On this basis,the vehicle interior noise,the near-field noise of the fuel tank and the vibration test of the fuel tank side and the vehicle side of the vibration isolation cushion were carried out.Through the comparative analysis of the test results,the reasons for the large noise caused by the fuel sloshing in the fuel tank of newly designed passenger cars are found.Finally,the measures of installing anti-wave baffle in the fuel tank and partially improving the structure of the fuel tank are taken to effectively restrain the fuel sloshing.The research work and main conclusions of the thesis are as follows:(1)Subjective evaluation of the fuel tank sloshing noise of 4 kinds of driving conditions and 4 kinds of fuel filling level for the new car and its benchmarking vehicle.The results show that the benchmarking vehicle has no obvious fuel sloshing noise in any driving condition and fuel tank filling level.And the newly developed car has the most severe sloshing noise when the creeping driving condition and the 100% fuel tank filling level.(2)For the newly developed car and its benchmark car,the vehicle interior noise,the fuel tank near-field noise and the vibration isolation cushion fuel tank side and body side vibration are tested under the creeping condition and 100% fuel filling level of the fuel tank.The test results show that the vibration of the fuel tank body and the vibration isolation performance of the vibration isolation cushion of the newly developed vehicle are the main reasons for the large fuel sloshing noise.(3)Based on Fluent software,a two-phase three-dimensional flow field simulation model of fuel tank sloshing of new car fuel tank was established,which simulates the fuel sloshing of the new car during creeping driving conditions and fuel tank 100% fuel filling.The result shows that the fuel inside the fuel tank has a sharp sway during deceleration and acceleration state of the vehicle,and the impact on the fuel tank wall is large.On this basis,the fuel tank wall pressure obtained by the three-dimensional flow field simulation is used as the excitation force,and the vibration of the fuel tank body is analyzed.The results show that the vibration acceleration at the installation position of the left front vibration cushion of the fuel tank is the largest,the right front is the second,the right rear is the smallest.And the simulation results are consistent with the trend of the vehicle road test results.So the above numerical simulation method can be applied to the scheme comparison of the subsequent fuel tank structure improvement.(4)Combined with the above test and simulation results,the fuel tank structure is improved from the buffer fuel sloshing and the rigidity of the tank.According to the fuel tank structural characteristics,two kinds of anti-wave baffle are designed.And the better structure of anti-wave baffle with better anti-sloshing effect was selected through three-dimensional flow field simulation of fuel sloshing and vibration simulation of fuel tank structure.Finally,the improved fuel tank is installed on the whole vehicle for road test.The results show that the near-field sound pressure level is significantly reduced about improved fuel tank;in the left front vibration isolation cushion installation position where the original fuel tank vibrates the most,the vibration acceleration is reduced to the original 40% of the fuel tank.The above results show that after the fuel tank structure is improved,the fuel sloshing is effectively suppressed,which can effectively reduce the fuel sloshing noise inside the vehicle.