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A new measuring technique of gas stream velocity has been developed, based on the phenomenon that the path of an electric discharge moves downstream under the influence of the gas stream. A probe (a thin conductive wire grounded by a resistance) is placed at a fixed distance downstream from the electrodes. When the discharge path arrives at the probe, the probe voltage rises rapidly. By means of measuring the time interval elapsing between the beginning of the spark and the rising of probe voltage, the stream velocity can be determined by the formula, U = Kℓ/τ, where K is a constant. As the result of preliminary tests, it was confirmed that the constant K is independent of distance ℓ, intensity of turbulence, temperature, and pressure of flowing gases, and depends only on the electrode spacing. The digital measurement of the time interval can be made easily.

In a 2-stroke cycle crankcase-scavenged gasoline engine, the compositions of cylinder gas and exhaust gas were investigated by analysis of the sampled gas extracted from the cylinder and exhaust pipe. As is well known, the combustion process taking place in a 2-stroke cycle gasoline engine has cycle-by-cycle variations. In this study, a new method controlling the operation of the sampling valve was applied, which enabled us to select cycles showing the same peak pressure and to extract a combustion gas produced by the similar combustion process. From these data the following were confirmed: 1. For estimating the composition of combustion gases, simple equations of combustion reactions are available. 2. The most reliable values estimating the scavenging properties may be calculated from the change of O2 concentrations of sampled gases before and after scavenging. 3.