Theory and Measurement Techniques

This paper investigates the effects of non-identical ultrasonic transducers on reciprocity and zero-flow calibration in transit time flow meters. According to the theorem of reciprocity, there should not be any difference between the up-and downstream acoustic times of flight in a zero-flow situation. This would thus eliminate zero-flow estimation drifts. The flow meter is modeled as a one dimensional system with equivalent electrical circuits and simulated with simulation program with integrated circuits emphasis. The work shows that variations between the two transducers cause false estimates of flow and indicate which parameters have the largest influence. It indicates that reciprocity holds only for identical transducers. Ó

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“…From the time of the pulses' flight, the direction of the flow, its velocity and the velocity of sound in the fluid can be estimated [1]. Fig.…”

Section: Introductionmentioning

confidence: 99%

Apparent transducer non-reciprocity in an ultrasonic flow meter

Deventer

Delsing

2002

Ultrasonics

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“…A propagation delay corresponds to a modification of distance, so if we measure the delay and knowing the speed of sound, we can evaluate how far the particle moved, and as we know the delay between the pulses, we can compute the speed of the particle [4]. This measurement principle is illustrated in Figure 3.…”

Section: Ii2 Measuring Flow Ratementioning

confidence: 99%

Estimation of thermo-hydrodynamic parameters in energy production systems using non-stationary signal processing

Birleanu

Ioana

Șerbănescu

et al. 2010

2010 Conference Record of the Forty Fourth Asilomar Conference on Signals, Systems and Computers

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Abstract-In order to control water flow in power generation systems, obtaining precise information about the parameters of the flow is important. The construction of such systems, as well as the operating conditions, impose the use of non-intrusive techniques. The use of ultrasounds allows solving this problem in a simple and elegant manner. The technique consists in sending a signal to be affected by the flow without sensibly interacting with it, and then extracting the desired parameters of the flow from the received signal. The paper first presents how the acoustic wave is altered by the propagation in the liquid environment, and then it studies the means to analyze the received signal in order to obtain from it information about two important parameters of the flow -the temperature of the water and the flow rate. Polynomial phase modeling is used, for obtaining a good estimation of the propagation times. Keywords:Non-intrusive measurement, ultrasounds, temperature and flow rate estimation, polynomial phase modeling.

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“…Air-coupled ultrasonic transducers are used in many application areas, including gas flow measurement [1][2] and non-contact inspection of materials such as paper, foam, and composites [3][4][5][6]. In a conventional ultrasonic transducer assembly, often comprising of a thickness mode piezoelectric transduction element, the impedance mismatch between the active piezoelectric element and the load medium limits the efficiency of the transducer.…”

Section: Introductionmentioning

confidence: 99%