| FSCC events require naturally aspirated internal combustion engines to be fitted with a restrictor valve with a circular cross-section between the throttle and the internal combustion engine for the purpose of limiting power.As the artery of the internal combustion engine,changes in its structural parameters can have a direct impact on the efficiency of the internal combustion engine in terms of inflation,intake resistance and the exit mass flow rate of each manifold,thus affecting the dynamics and emissions of the internal combustion engine.The design and optimisation of the intake system structure is therefore particularly important in the case of intake restriction.In this paper,the structural design and numerical simulation of the intake system of the CBR600,an internal combustion engine for FSCC vehicles,is investigated in order to address the unstable dynamics of the car in the FSCC competition.Firstly,based on the understanding of the current situation of the intake system at home and abroad,the fluid flow characteristics of the intake system are analysed.Combined with the overall layout of the racing car,the structural parameters of the air intake system were selected based on the dynamic effects and energy losses of the air intake system.Secondly,a one-dimensional simulation model of the whole internal combustion engine was established by using GT-POWER and combined with the bench experiment to complete the model verification.The influence of the radius of curvature of the intake elbow,the length of the intake manifold and the volume of the pressure stabilisation chamber on the power performance and inflation performance of the internal combustion engine was analysed,and the basic determination of the main structural parameters of the intake system was completed.On this basis,a three-dimensional model of the intake system including the restrictor valve,intake elbow,pressure stabilising chamber and intake manifold is established and analysed by numerical simulation to obtain pressure and velocity vector diagrams of the restrictor valve with different expansion and retraction angles.The optimum chamber structure is determined by comparing the inlet and outlet mass flow rates of the intake manifold and the optimum chamber structure;the transient simulation of the optimum intake system is carried out using UDF to verify the rationality of the intake system model.Based on the above research,the main structural parameters of the intake system restrictor valve,the radius of curvature of the intake elbow,the length of the intake manifold,the volume and the structure of the pressure regulator chamber of the FSCC vehicle internal combustion engine CBR600 are determined,and finally the intake system is completed.3D solid printing and whole machine assembly and road test.The test results show that the power and torque of the internal combustion engine are both 3% to 6% higher than those of the school in 2020. |
