Study On The Calculation And Control High Pressure Common Rail System For Marine Diesel Engine

In marine common rail system,rail pressure has a direct effect on injection quantity,and the quantity shows great difference with different pressure waves.A better control of rail pressure will greatly improve performance of the diesel engine.It's analyzed in this thesis to improve rail pressure control strategy of marine common rail system from two aspects of control model and method,including the finite element method of fuel flow,optimization of rail pressure control strategy,and test of simulation for the rail pressure control strategy.In the finite element method section,a three-dimensional model of the flow in the RT-flex marine common rail was built based on Fluent.With the use of SIMPLE and UDF,the pressure wave propagation rule and threedimensional distribution was shown through the simulation result.The causes of rail pressure fluctuation are analyzed through spectrum analysis and feedback boundary simulation,and the necessity of the optimization of common rail model is verified through the influence of rail pressure fluctuation with volume model and three dimensional model.In the optimization section,the common rail model is optimized based on the conclusion of the finite element method section.The high frequency fluctuation is considered through the use of a sectional model of common rail.The control method of rail pressure is also optimized by using PSOPID,which is a self-adaptive PID controller,in order to meet the need of the control during the whole process.In the test section,the sectional model and PSO-PID are tested based on the process of variable speed.It can be shown from the difference between engineering tuning PID control and PSO-PID under the condition of variable speed and different disturbances,that the rail pressure fluctuation under the control of PSO-PID shows a better result.The results show that PSO-PID has obvious advantages in the aspects of the whole rail pressure fluctuation,the control of crests and troughs and the tracking performance of rail pressure,and PSO-PID will also reduce the workloads.