Research On Numerial Calibration Of Fuel Injection Parameters For Diesel Engine

Emission control regulations became stricter, while petroleum resource decreased day by day, in order to reduce the fuel consumption of diesel engine and control its emissions in current emission control regulation limit, maybe high-pressure common-rail injecting system will have to be used in diesel engines. For different cases, this system can obtain better dynamical performance, fuel economy and emission behavior at the same time by choosing the optimum injection parameters. Here injection parameters include injection pressure, injection duration and injection advanced angle. At present, to get the optimum injection parameters, namely injection parameter calibration, engine tests are mainly used. But this method costs heavily, and is difficult to test for extreme environment calibration even by paying enormous expense. At the same time, it's unusable for new designed engine, which has not been made out. So it's quite a meaningful work to dredge up new way for injection parameter calibration, such as getting the optimum injection parameters with simulation analysis method. In this paper, one high-pressure common-rail diesel engine with injection parameters unknown was illustrated, based on one-dimensional whole engine simulation, and injection parameters were figured out.One high-pressure common-rail diesel engine was taken as the template, its geometrical structural and performance parameters were used to found the simulation model. With the model, cases for different speeds and different loads were calculated. For the simulation, one-dimensional unsteady fluid flow theory and diathermanous theory were mainly used as the system info. In addition, Zeldovich model was used for nitrogen oxides approximate calculation, Nagle and Strickland-Constable model was used for soot approximate calculation. Taken dynamical performance, fuel economy and emission behavior as target, with optimizing tool of software GT-POWER, injection parameters under normal environment were obtained after simulation analysis, then a map of injection parameters was built. Further more, cases for extreme environment were analyzed, and the result indicated that performances of diesel engine were deteriorated heavily by extreme high temperature and extreme low pressure. In order to reduce the bad influence with engine structure unchanged, one way, that advancing the injection angle, shortening the injection duration and decreasing injection mass properly, was brought forward.It's quite difficult to calibrate injection parameters. Traditional method by engine tests is not only expensive, but also difficult to satisfy the precision, especially for extreme environment condition, just the working condition will be hard to set. However, numerical calibration method of injection parameters, which was introduced in this paper, can finish the same work as engine test and improve the precision with low costs. In addition, it can also calibrate a pattern engine, which provides one consult for new engines.