Research On Numerical Simulation Of Performance And Fuel Injection Control For Two-Stroke Kerosene Engine

Due to the low viscosity, low flash point, high volatility and easily firing, the inconvenience of gasoline appears in its transportation and usage. With the martial background, more and more vehicles and instruments are required for low volatile fuel as a single source in order to improve the safety, reduce the pressure of logistics support and minimize the number of instruments which use more than one kind of fuel. Nowadays, some gasoline engines installed on special vehicles partially use kerosene as a substitute fuel. Compared with the high technology in foreign countries, the Chinese kerosene engine technology gets behind in the international competition. So it needs far more researches and studies to apply the kerosene engines on vehicles, to keep engine running smoothly and gradually make the engine by ourselves in China.According to the requirements of some national deference pre-research project, the paper mainly included the data procurement from prototype engine, the simulation of kerosene engine working cycle numerical model, the research of modeling and controlling of fuel-injection system and the design of fuel-injection control system and fuel calibration system. And the mainly accomplished work and innovations are as follows:(1) In order to get the important testing data needed by the validation of engine numeric model and the mean value model, the engine data-acquisition system was built up based on the LabVIEW. Through the engine bench-test, many key data such as the pressure data within the combustion chamber were obtained. And then the mean mechanical-loss pressure of the prototype engine was figured out.(2) The numeric model of kerosene engine was built in the paper. The numeric simulation calculation was done based on the GT-Power Software. Through changing the compression ratio, air-fuel ratio, advance angle of ignition, intake pressure and temperature, a series of numeric simulations were accomplished. The paper analyzed the kerosene engine performances and knock characteristics in the different configurations and parameters. The variable law of the performance of kerosene engine was studied and theoretical basis for the kerosene was proposed in the parameters optimizing match.Due to the calibration strategy within the different working situations, the numeric simulation was applied, the air-fuel ratios within the different working situations were got and the kerosene engine initial fuel-injection MAP was figured out. So the period of the design of electric fuel-injection controller was reduced and thereby the work efficiency was highly improved.(3) Based on the mechanism modeling and testing modeling methods, the mean value model of two-stroke kerosene engine was suggested. Meanwhile the fuel-injection control model of two-stroke kerosene engine was also built up. In order to accurately control of the fuel-injection in both the stable state and transient state, the oil membrane compensation control strategy was introduced. In the paper, the linear variable parameter state-space model and the fuel-injection impulse width model in both the stable state and transient state were proposed. And the simulation validation was applied on the control of fuel injection in these states. The simulation results show that the fuel-injection control based on the linear variable parameter state-space model is able to meet the accurate controlling requirements, so the strong theoretical basis is supplied in the design of kerosene engine control system.(4) In order to achieve the accurate fuel injection in kerosene engine, the kerosene engine fuel-injection controller was designed based on the Freescale 16 embed microcontroller including the design of hardware circuit and control software. The designed controller has many advantages such as the ability of anti-electromagnetic interference, self-protection and running stably. In order to monitor the controller data in-time, the computer monitor software and engine calibration software were designed based on the Visual C++6.0. This software could read, display and amend the data of fuel-injection in the MAP and also save the data and analyze after tests.(5) The engine half-physical simulation test was accomplished. The simulation results show that the designed fuel-injection electric control unit can cover the requirements of engine performance. The electric control unit has high ability to resist the electromagnetic interference. Also the electric control unit is able to work stably in certain electromagnetic interference environment. And the fuel-injection calibration system also has strong functions and works stably.(6) The prototype fuel-injection electric control unit was tested on the engine testing board. And the test shows that this electric control unit could satisfy many work states such as start, idle, rapid speed up and stable working conditions. The designed electric control unit could work stably and the hardware and software of electric control unit are also well performed with high ability of anti-electromagnetic interference.The updated fuel-injection electric control unit was tested on the real engine testing board. And the testing results shows that the initial kerosene MAP from numeric optimizing calculation could be well performed in the stable-state running of the kerosene engine. The control strategy of fuel-injection model could satisfy the engine testing controlling requirements in both the stable state and transient state with good control performance.Meanwhile, the testing results shows that when the kerosene was applied in the test the performance of power was declined a bit due to the heat value of the mixture decreases, the atomization effects of the fuel become worse, and so on.