A Study on enhancement of the turbulence around the spark timing by auxiliary injection during the compression process

Abstract

It has been found in a previous study that enhancing the turbulence intensity at the beginning or middle of the compression process and generating the strong turbulence at the end by the compression effect is desirable in order to create and maintain the high level of turbulence around the spark timing. This study aims at analysing and evaluating the auxiliary injection method for inducting the pressurized air at the beginning of the compression process to enhance the level of turbulence around the spark timing. An electronic solenoid valve is fitted to the auxiliary injection device for the purpose of active control of the in-cylinder turbulence characteristics. The level of in-cylinder turbulence with the auxiliary injection increases by about 40 per cent compared with a conventional engine. A desirable distribution of turbulence around spark timing with lower levels of turbulence around the spark plugs and cylinder wall and with a higher level near the half-radius of the cylinder is obtained by the auxiliary injection. Furthermore, the conditions suitable for injection are identified with respect to injection direction, injection pressure and injection timing.