저속디젤기관의 연료분사계통 시뮬레이션에 관한 연구

Abstract

Diesel invented the compression-ignition engine in 1892. Since that time these engines have continued to develop as our knowledge of engine processes has increased. So, nowadays they play a dominant role in the fields of automobiles, ships and some prime movers. But now worldwide concerns with global climate and environmental protection changed the trend of diesel engine researches to solve the problems how to reduce the pollutant emissions from diesel engines to meet the restrict emission regulations by the IMO(International Maritime Organization).

There are several method that reduce the emission. First of all, the fuel injection system of a diesel engine has taken more important place in understanding of diesel combustion process with combustion chamber, and has taken one of the most important part to prevent environmental pollution by exhaust gas from diesel engine. From this point of view, many investigations have been carried out to solve this problem, such as adopting higher injection pressure and shortening the injection duration by the higher injection rate, etc. Owing to this effort there are considerable improvement to solve pending issues.

But these researches are mainly on the high speed diesel engine or spark ignition engine, therefore it is worth while to study the low speed diesel engine for ship's use to compare the results which was well known for general trend by the previous researches.

In this study the analysis was carried out by simplifing and modeling the injection phenomena and dividing into three parts comprising of fuel injection pump, high pressure pipe and fuel injection nozzle in the fuel injection system of a low speed diesel engine. A computer simulation model was developed using the Runge-kutta method to solve the equations for each part(fuel injection pump, high pressure pipe and fuel injection nozzle) and the method of characteristics to analyze the unsteady flow in the fuel injection system considering cavitation and variation of fuel density and bulk modulus. Applied was the constant pressure condition at the nodes in the high pressure pipe.

Comparison was commenced between the calculated data and experimental data of pressure and injection quantity at the fuel oil distributor in fuel injection system for the training ship hanara. In the work presented here, the results of a new model which was developed about low speed diesel engine was similar trend to earlist works in the high speed engines. Simulation results about the effect of the high pressure pipe diameter, length, sac volume and efflux coefficient was also analyzed.