Abstract:Experimental study on the effects of Ar-O2 atmosphere on ion current characteristic of natural gas in an SI engine was conducted. Engine fueled by natural gas was modified base on an inline two-cylinder diesel engine. Air was replaced by oxygen and argon (with higher specific heat ratio) mixture as engine intake gas. Results show that the ion current strength increase significantly under Ar-O2 atmosphere compared with air. When argon percentage is 79% or lower, the eigenvalue of ion current is corresponding very well with combustion characteristics calculated by pressure. Ion current can detect knock reliably, but it is insensitive to knock’s intensity.
