Study on combustion model parameters of high pressure common rail diesel engine under transient operation

Simulation and optimization tests can be carried out on the control strategy of high pressure common rail diesel engine in HIL (Hardware in loop). The high-precision real-time engine model is the key part of the HIL tests. The regularity for the change of the characteristic parameter in instantaneous conditions in the Wiebe´s functions of the combustion model should be known so as to set up the HIL of diesel engine´s transient operation. Therefore, the incylinder pressure, the inlet air flow and the fuel injection control parameters were tested under the instantaneous conditions when the load of a high pressure common rail diesel engine at rated speed of 1500r/min increases to 100% from 30%. The combustion heat release rate of each circle was simulated during the loading process with three combined Wiebe´s functions. With the parameters under steady-state conditions as the initial values, the four characteristic parameters were illustrated through a nonlinear regression equation, the regularity for the change under instantaneous conditions was analyzed, the empirical equation for selecting Wiebe´s functions were derived, and the regularity of heat release under instantaneous conditions was forecasted, so that the real-time model under instantaneous conditions will be more accurate than before.