Parallel strip waveguide for ultrasonic flow measurement in harsh environments.

Wetted ultrasonic transit time flow meters typically consist of one or more pairs of transducers, containing piezoelectric elements, which alternate between transmitting and detecting an ultrasonic pulse. Typical piezoelectric materials and the adhesives used to attach the piezoelectric element in such devices can be damaged by hostile environments, such as extreme temperature, potentially limiting possible applications of ultrasonic flow measurement techniques. We have investigated a design for a flow meter with an integrated thermal buffer waveguide consisting of five parallel stainless steel strips.

Sound speed and density characterization of milk adulterated with melamine.

Milk contaminated with melamine resulted in an important health hazard that affected many babies in China recently. Ultrasonic characterization of adulterated milk may detect gross levels of melamine contamination. Sound speed and density measurements were made in skim milk as a function of melamine adulteration.

Extensional bundle waveguide techniques for measuring flow of hot fluids.

A bundle of acoustically slender metal rods, each thin compared to wavelength, tightly packed within a sheath, and welded closed at each end, provides a dispersion-free waveguide assembly that acts as a thermal buffer between a transducer and the hot fluid medium the flow of which is to be measured. Gas and steam flow applications have ranged up to 600 degrees C. Liquid applications have ranged from cryogenic (-160 degrees C) to 500 degrees C and include intermittent two-phase flows.