Simulation Study on the Process of Pressure Wave Propagation for High-Pressure Common Rail Diesel Engine

In this paper, pressure fluctuation in a high-pressure common rail system has been investigated through numerical simulation method. By establishing a three-dimensional (3D) model and one-dimensional (1D) simulation model of a high-pressure common rail system validated by the experiment, three essential parameters (needle lift, injection pulse width, and the pressure in common rail) of the common rail system were investigated, and their effects on pressure waves’ characteristics were evaluated with a 1D model. Combined with the results of the 3D simulation, the pressure wave generation, propagation, and fuel flow vector in high-pressure pipelines are studied. The results illustrated how each geometric parameter affects the pressure fluctuations. The pressure waves mainly include the expansion wave generated by the fuel injector spray and the compression wave generated during the fuel supply, and the pressure waves are reflected and superimposed in the process of propagation. Due to the continuous conversion of fuel kinetic energy and pressure wave energy, the fuel pressure distribution in the high-pressure pipeline changes with time, and in the process of the conversion between fuel kinetic energy and pressure wave energy, energy loss is inevitable.