Liquid-solid phase transition detection with acoustic plate mode sensors: Application to icing of surfaces

Abstract

Abstract An acoustic plate mode (APM) device operating at 158 MHz has been used to monitor liquid-to-solid phase transitions. Shear-horizontal plate modes propagating in a quartz plate probe the phase of a medium in contact with the plate. When liquid contacts the device, viscous damping of the APM is the dominant means of energy transfer, with the resulting APM attenuation serving as a measure of liquid viscosity. When the liquid freezes, acoustic energy is mechanically coupled from the plate into the adjacent solid, leading to a dramatic increase in APM propagation loss. Because effective coupling of acoustic energy from the plate into the adjacent medium depends on continuity of shear displacement across the solid/ solid interface, the magnitude of the propagation loss is an indication of the intimacy of contact between the solid and the APM surface. Possible applications of this sensor include a monitor for airplane wing icing.