Fast-response Simultaneous Measurement of Concentration and Velocity in Mixing of City Gas and Air.

This paper presents a fast-response simultaneous measurement method of velocity and concentration in the mixing of air and city gas mainly composed of methane. The measurement of city gas concentration and fluctuation utilizes the absorption of a laser light by methane in the mixture. A hot-wire anemometer is used to measure velocity. It is shown that the effect of the change in the thermal conductivity of the mixture on a hot-wire anemometer signal can be compensated by using the measured city gas concentration at the same time and location. This method is applied to the simultaneous measurement of concentration and velocity as well as fluctuation in a coaxial flow of city gas and air.