Ultrasonic flow meter

About: Ultrasonic flow meter is a research topic. Over the lifetime, 3243 publications have been published within this topic receiving 29772 citations.

Coriolis mass flow rate meter having a substantially increased noise immunity

Abstract: Apparatus and accompanying methods for use therein for a Coriolis mass flow rate meter which is substantially immune to noise, and more particularly, to such a meter that is substantially unaffected by noise that occurs at substantially any frequency different from a fundamental frequency at which the flow tube(s) in the meter vibrate Specifically, the meter relies on measuring mass flow rate by determining the phase difference that occurs between real and imaginary components of the discrete fourier transform (DFT) of both the left and right velocity sensor waveforms evaluated at the fundamental frequency at which the flow tubes vibrate The fundamental frequency is located, during an initialization operation, by providing a power spectrum, determined through use of the DFT, of one of the sensor signals and then selecting that frequency at which the magnitude of the power spectrum reaches a maximum value In addition, the frequency at which both velocity sensor signals is sampled is readjusted in response to any change in the phase of one of the velocity sensor signals, as transformed using the DFT, in order to assure that the sampling frequency always remains substantially equal to a pre-defined integer multiple of the fundamental frequency Furthermore, the meter, through use of the numerical value of any such phase change, also provides a density indication which is also substantially immune to such noise

Development and evaluation of an ultrasonic ground water seepage meter.

Abstract: Submarine ground water discharge can influence significantly the near-shore transport and flux of chemicals into the oceans. Quantification of the sources and rates of such discharge requires a ground water seepage meter that provides continuous measurements at high resolution over an extended period of time. An ultrasonic flowmeter has been adapted for such measurements in the submarine environment. Connected to a steel collection funnel, the meter houses two piezoelectric transducers mounted at opposite ends of a cylindrical flow tube. By monitoring the perturbations of fluid flow on the propagation of sound waves inside the flow tube, the ultrasonic meter can measure both forward and reverse fluid flows in real time. Laboratory and field calibrations show that the ultrasonic meter can resolve ground water discharges on the order of 0.1 microm/sec, and it is sufficiently robust for deployment in the field for several days. Data from West Neck Bay, Shelter Island, New York, elucidate the temporal and spatial heterogeneity of submarine ground water discharge and its interplay with tidal loading. A negative correlation between the discharge and tidal elevation was generally observed. A methodology was also developed whereby data for the sound velocity as a function of temperature can be used to infer the salinity and source of the submarine discharge. Independent measurements of electrical conductance were performed to validate this methodology.

The Dependence of Ultrasound Doppler Bandwidth on Beam Geometry

Abstract: .4bstrmt-The output spectrum of ultrasound Doppler flowmeters contains information about flow parameters such as degree of turbulence, flow velocity gradient, and direction. This information can be extracted if the effects of the sound beam geometry on the Doppler spectrum can be understood and controlled. Equations for calculating the Doppler output signal bandwidth caused by constant velocity flow through the waist of focused transducers and through the intermediate and far field of unfocused transducers are derived and experimentally verified in this paper. The results presented show how to minimize the bandwidth caused by beam geometry and thus maximize the accuracy of flow parameter estimation. It is also shown that the angle between flow and beam can be estimated from the Doppler bandwidth if the velocity gradient in the range cell is small enough and if flow is laminar.

Theoretical Analysis of the CW Doppler Ultrasonic Flowmeter

Abstract: The widespread application of ultrasonic techniques for the measurement of pulsatile blood flow has been hampered by the lack of a detailed theoretical understanding of the Doppler ultrasonic flowmeter. A general model for the Doppler flowmeter based upon stochastic considerations of the scattering of ultrasound by blood is introduced in this paper. The model characterizes the back- scattered ultrasound as a Gaussian random process and the expression for the autocovariance function is derived. For the CW Doppler flowmeter, the power spectral density function is computed, and its significance is emphasized: measurement of blood flow velocity corresponds to estimation of the average frequency of the Doppler power spectrum.

The accuracy of the bubble meter method for gas flow measurements

Abstract: The bubble meter technique is an absolute method of measuring the volume flow rate of gases. It requires accurate standards of mass and time only and is simple in application. This paper describes the method, examines its potential accuracy and derives criteria for design. It is found that errors may be kept below ±1% for flows between 0.1 and 1000 cm3 sec-1, while the error may be reduced to ±¼% for flows between 0.1 and 100 cm3 sec-1. Modifications to extend these limits are discussed.