Technical Paper
A New Digital Method for Measuring Gas Flow Velocity by Electric Discharge
1969-02-01
690180
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.