Acoustic flowmeter for the measurement of the mean flow velocity in pipes

This paper proposes a new technique for measuring the gas flow velocity ave raged along the finite length of a pipe as well as over its cross-sectional area. Unlike the conventional gas flowmeters, the proposed technique explo its the one-dimensional plane waves that propagate uniformly across the pip e cross-sectional area. When a fluid flows along the pipe, the plane waves are superposed with the flow field such that the positive-going and negativ e-going plane wave components undergo the change of their wave numbers. Suc h wave number variation due to the mean flow velocity has provided a major motivation for developing a new way of measuring the mean flow velocity in the pipe, which is referred to as the acoustic flowmeter. To examine the fe asibility of the developed flow velocity measurement method, including its theoretical backgrounds, experimental setups are illustrated in this paper. Detailed experimental data for the flow velocity range of 2-27 mls reveal the linearity of the proposed acoustic flowmeter and its salient environmen tal robustness for the different acoustic pressure patterns in the pipe and , furthermore, for different velocity profiles over the pipe cross-section area. (C) 2001 Acoustical Society of America.