An Empirical Study On Influence Of Injection Parameters On Mixture Formation And Performance Of Diesel Engine

Injection parameters plays a decisive role on fuel spray atomization, thus affect the mixture formation and combustion of diesel engine. Using numerical simulation method to analyze the influence law of injection parameters on fuel spray atomization, mixing and combustion process, has very important significance to optimize the combustion process, improve engine performance and reduce emissions.This paper use three-dimensional simulation software FIRE to establish a type of combustion simulation model of diesel engine, then the spray and combustion process was numerically calculated, the change rule of temperature field and concentration field in cylinder can visually reaction the influence of injection parameter on mixing and combustion process. Characterization of mixing and combustion process parameters(turbulent mixing rates, beam penetration distance, fuel evaporation rate, etc.) were analyzed to study the influence of injection advance angle, injection pressure and injection nozzle diameter on fuel spay atomization, mixture formation and combustion process. Some factors of affecting the diesel engine performance and emissions were analyzed to put forward the corresponding optimization strategy.The results showed that the injection advance angle, injection pressure and nozzle diameter have very significant effect on the spray combustion process. As a basis for change rules of flow field in cylinder and engine performance, put forward the corresponding injection parameter optimization strategies. Increasing injection pressure or reducing nozzle diameter, the oil droplet average diameter decreases, the contact area with air increases, fuel evaporation rate is accelerated, the oil and gas mixing speed, it is easier to form mixture, combustion temperature and pressure in cylinder increases, the generated NO increases, the SOOT decreases; increasing fuel injection advance angle, ignition delay period becomes longer, the more mixture is formed, the maximum combustion temperature and pressure rise, the generated NO increases while the SOOT decreases. Appropriate injection advance angle will improve diesel power and economy performance.Use the influence law of injection advance angle on diesel engine performance in the simulation results, to determine the best injection advance angle range. Through experimental test, verified the influence of injection advance angle on diesel engine performance, the simulation model can effectively reaction mixture combustion law of diesel engine, and solved the confidence problem of three-dimensional flow field simulation. Combining simulation and experimental test, the optimum interval of injection advance angle can be effectively obtained, with a guiding significance for actual calibration and optimization work.