Viscosity measurement using laser generated ultrasonic wave application

The major problem in measuring the viscosity of a molten fluid product is the extremely hot and corrosive environment which is often found in a manufacturing environment. Previously reported work has been limited to measuring an average viscosity value across a cross-section of fluids using attenuation measurements. In this work a non-contact method for the in-situ monitoring of viscosity of liquids/melts at extreme temperatures was demonstrated. The basic technique involves measuring the shear wave reflection coefficient characteristics between the liquid and a solid interface. The shear wave reflection coefficient is a function of the product of the liquid density and viscosity. It is also a function of the elastic properties of the solid. If the elastic properties are well characterized, then the density-viscosity product can be determined. The density can be determined from the compressional wave reflection coefficient.