The analysis and results of a continuous wave ultrasonic densitometer

This paper investigates an ultrasonic densitometer capable of measuring the densities of liquids. Lynnworth originally proposed an ultrasonic densitometer operating in pulse-echo mode. This instrument makes use of the phase velocity of a torsional elastic wave pulse traveling in a noncircular waveguide immersed in a liquid to indicate the density of the liquid under investigation. In this paper a second mode of operation is proposed by making use of a continuously excited torsional wave to reveal liquid density. An important advantage of this mode of operation is the larger cross-sectional dimensions possible without sacrificing performance degradation which might result from wave dispersion. The theory of this mode of operation is described and used to construct a densitometer. Densities of a few liquids are measured and compared to the theoretical values.