Non-linear and unsteady flow analysis of flow in a viscous flowmeter

Abstract

An experimental and theoretical investigation has been undertaken on a viscous flowmeter, with both steady and unsteady flow. The steady flow analysis quantifies the nonlinear effects of entry and exit losses, development length effects and compressibility effects. The steady flow analysis and experiments show that the pressure drop has a quadratic response to flowrate, but that for practical applications a linear approximation will lead to an error of less than 1%.The unsteadyflow experiments show that it is necessary to integrate the instantaneous flow over a whole number of cycles, in order to obtain reliable values of the mean flow. An analysis of unsteady viscous flow has been used to show how the instantaneous pressure difference measured across the viscous flowmeter can be analysed to give the instantaneous volume flow rate.

Development of slit-type pressure differentiator using an isothermal chamber

“…Next, the flow rate transfer dynamic characteristics of the laminar flow element are considered. Numerous studies on flow rate dynamic characteristics in narrow pipes and thin slits have been conducted [8]. When thin slits are used as a laminar flow element, the dynamic characteristics can be evaluated by a dimensionless quantity called the Womersley number W n , which presents the ratio of frequency f to the viscosity µ [9].…”

A concentration measurement system for binary gas mixtures using two flowmeters

“…Experiments were conducted in order to clarify the changes in coefficient α l . The coefficient is affected by the gas properties related to the pressure loss at the inlet length, the developing flow in the entry length and the effects of compressibility, those are nonlinear to flow velocity, but could be linearized in equation ( 4) [9]. The flowmeters were calibrated with critical nozzles (Hirai Co. Ltd) and the uncertainties are less than 0.2% authorized in Japanese calibration service system (JCSS) accredited laboratories.…”

Detection of turbulent error by helicity in an ultrasonic flowmeter

“…Various experimental and numerical methods are available to study transient pipe flow. Stone and Wright (1994) and Kalpakli (2012) applied a fast pressure transducer to study the characteristics of unsteady flow in a pipe, but the sampling area was limited by the installation. Islek (2004) and Sumida and Senoo (2015) used laser Doppler velocimetry (LDV) to extract undeveloped turbulence information.…”