Kim J O, Bau H H, Liu Y, Lynnworth L C, Lynnworth S A, Hall K A, Jacobson S A, Korba J A
Centre for quality Eng. and Failure Prevention, Northwestern Univ., Evanston, IL.
IEEE Trans Ultrason Ferroelectr Freq Control. 1993;40(5):563-76. doi: 10.1109/58.238110.
A solid corrosion-resistant torsional waveguide of diamond cross section has been developed to sense, online and in real-time, the characteristics of the liquid in which it is submerged. The sensor can measure, among other things, the liquid content of a bubbly medium, the density of adjacent pure liquids, the equivalent density of liquid-vapor mixtures or particulate suspensions, a suspension's concentration, and the liquid level. The sensor exploits the phenomenon that the speed of propagation of a torsional stress wave in a submerged waveguide with a noncircular cross section is inversely proportional to the equivalent density of the liquid in which the waveguide is submerged. The sensor may be used to conduct measurements along distances ranging from 20 mm to 20 m and over a wide range of temperatures and pressures, e.g., from the cryogenic temperature of liquid nitrogen, -196 degrees C, up to hot pressurized water at 300 degrees C and 7 MPa. A self-calibrating three-zone sensor and associated electronics have also been developed to compensate for any sensor inaccuracies due to operation over a wide range of temperature.
