Employment of temperature waves superposition in method of absolute measurement of gas flow velocities down to the sub 1Â m/s range

Due to specific metrological properties, the problem of measurement of gas flow velocities down to the sub 1 m/s range comprises a distinct metrological challenge. One of the measurement methods used in this range of flow velocities is the method based on investigation of the propagation of heat waves generated in the flow. Such method does not require calibration and provides measurements of minimal invasiveness. This study presents a new variant of this method implementing two transmitters of temperature waves connected in series and a single detector. The main principle of the method is based on the phenomenon of superposition of temperature waves. The method may find its application especially in mobile measurement devices, micro flow meters and measurement circuits based on MEMS technology.