Research on the Fundamental Property of Flanged Spark Plug and Application to Natural Gas Engine

Abstract

Spark ignition characteristics of flanged spark plugs have been studied experimentally. Experiments were performed using a constant volume combustion chamber and a natural gas engine. Flanged spark plugs were made by remolding spark plugs on the market. The minimum ignition energy was employed to evaluate the ignition characteristics of the flanged spark plugs. It was found that the flanged spark plug reduces the minimum ignition energy. It was observed by schlieren photography that the shock wave was reflected by the flanges concentrated on a flame kernel. This fact suggests that the adiabatic compression due to the shock concentration reduces the minimum ignition energy. There is little effect of the flange on the flame speed, although it is well known that the existence of flanges prevents the initial growth of the flame kernel. It was found that, in actual engine test, the ignition probability is increased and the lean limit is extended.