Gas Sampling Valve for Measuring Scavenging Efficiency in High - Speed Two - Stroke Engines

Measurement of short-circuiting and its effect on the controlled autoignition or homogeneous charge compression ignition combustion in a two-stroke poppet valve engine

“…In the history of developing and improving two-stroke engines, researchers had long recognised the issue of short-circuiting during the scavenging process in twostroke engines and resolved to measure the shortcircuiting and scavenging efficiency through liquid simulation techniques in a model engine 11,12 and through the gas visualisation technique in motored engine operation. 13,14 Although some other methods for the measurement of the scavenging efficiency of a port scavenged two-stroke engine had also been tried, [15][16][17] the first widely used experimental method to measure the short-circuiting was proposed by Jante 18 using the distribution of the gas velocity measured by the pitot tubes first in motored conditions, and then it was further developed for measurement under firing conditions. 19 Another experimental method for measurement of the scavenging efficiency was postulated in the late 1940s based on measurement of the oxygen concentration 20 and implemented in 1985 to determine the effect of the engine design on the scavenging, trapping and charging efficiencies.…”

Experimental investigation of scavenging in two-stroke engines using continuous CO2 sampling

“…Experimental scavenging studies can be categorized in multiple ways, for example engine-based studies or model-based ones. [13][14][15][16][17] based on the nature of the test bed; firing 11,[18][19][20][21] or non-firing studies based on the nature of engine operation; visual 13,14,19,20 or non-visual studies based on the observation tools used; dynamic 14,22,23 or static investigations 15,24 depending on whether the piston is moving or not; and sampling [25][26][27][28][29][30][31][32][33][34] or non-sampling studies based on the drawing (or lack thereof) of gas samples from the engine. Rizk 24 provides a good classification of various investigation methods used in experimental scavenging studies.…”

“…Previous tracer sampling-based studies. [25][26][27][28][29] have mostly relied on synchronized electromagnetic or camactuated sampling valves to draw cylinder and/or exhaust samples at appropriate times during gas exchange, that is intermittent sampling. The potential challenges with such studies are: (1) to obtain representative composition samples because of the heterogeneity of the scavenging mixture and (2) to obtain sufficient quantities of the samples that they can be analyzed by an emissions analyzer.…”