Nonintrusive In-Line Rheometry Using Ultrasonic Velocity Profiling
Yuji Tasaka, Taiki Yoshida, Yuichi Murai
Abstract
We present a new approach to realize nonintrusive in-line rheometry without measuring the pressure difference along the pipe, which is required in conventional methods that insert pressure probes in the pipe. The rheometry utilizes unsteadiness of target pipe flows reflected by spatiotemporal velocity information. The quasi-instantaneous rheological properties were estimated by inverse analysis of the equation of motion, which governs unsteady one-directional pipe flows, in the frequency domain. To evaluate applicability of the present in-line rheometry as “viscometry”, a numerical experiment was performed using solution of pulsatile pipe flows with different viscosities and frequencies. The limitations of the viscosity measurement range considering the thickness of the viscous layer formed on the pipe wall are discussed. We demonstrated the utility of our method on a laboratory pipe loop facility with viscous silicone oil as the test fluid. Finally, we quantified the time variation of the viscosity due to transient temperature variation of the fluid.