Physical and Electrical Characterization of Non-newtonian Multiphase Fluids Using Bimorph Piezoelectric Cantilever

Determination of fluid properties in situ in processing facilities is, at times, very challenging due to varying conditions and different design requirements that require individual sensors or transducers. In some processing installations, fluids are subjected to adverse environments such as high pressure or low temperature, which requires sensors that account for such conditions. The study analyzed theoretically and experimentally a biomorph composite cantilever sensor driven by the piezoelectric ceramic layer to determine the viscosity and density of different fluids as a function of frequency. The study was conducted under room temperature where excitation of the piezoelectric transducer has generated resonance frequency as a function of impedance and admittance while the cantilever is immersed in a fluid. A finite element analysis was run to model the cantilever behavior while immersed in a water. Results showed a damping behavior as opposed to the harmonic oscillation in air. This study followed an oscillating sphere rigid model, which considers the cantilever tip as an oscillating sphere. This model introduced a fluid damping coefficient and an added mass, fluid attached to the vibrating tip, to account for fluid effects when the cantilever is immersed in a fluid. The results indicated that the model predicts the resonance frequency for given fluid viscosity. The predicted viscosity provided a close agreement until 60 mPa.s but didn't provide a good agreement with the measured data at high viscosity data, which might be due to incorrect composite materials and geometrical correction factors. The measured quality factor was found to change shape as a result of dissipative losses due to fluid viscosity. On the other hand, frequency damping was found to be as a result of fluid density. Upon completion of this study, the sensor will be used to test the viscosity of a multiphase fluid system in situ under semi-frozen conditions.