SU115993A1 - Ultrasonic device for measuring the flow rate - Google Patents

Description

The proposed ultrasonic device for measuring the flow rate in a pipeline is of a known type of devices of the same purpose, containing two piezoelectric elements arranged along the pipeline, periodically switched from transmission to reception, and a phase meter determining the phase shift between the signals emitted and the received signal characterizing the desired flow rate. A significant drawback of the known devices is the dependence of their readings on the parameters of the medium — temperature and density.

In order to eliminate the influence of these parameters, thereby improving the measurement accuracy, a two-channel transducer synchronously switched to the specified phase meter is connected: synchronously switching the piezoelectric elements and converting the output voltages of the phase meter to signals that are inversely proportional to the corresponding phase shifts and supplied to the totalizer.

The drawing shows the diagram of the proposed device.

Electrical oscillations (with a frequency of 300 kHz from generator 1 are transmitted to radiating piezoelectric element 2, which converts them into ultrasonic vibrations and guides through the pipe wall to a controlled medium. Passing through a fluid note, ultrasonic oscillations are received by the second piezoelectric element 2 and again converted into electrical oscillations In order to increase the sensitivity and stability of the device, piezoelectric elements 2 by means of switch 3 are periodically switched from transmission to reception, resulting in ultrasound oscillation stems are guided alternatingly downstream and upstream.

Electrical signals from the output of piezoelemite 2 y-silica in amplifier 4 and do not come with the switching frequency of the phase meter 5, to which also the voltage p is applied:; generator /. At the output of the phase meter, constant voltages are obtained proportional to the phase shifts:

No. 115993-2 -

U, K, and u2,

where: Ll and (/ 2- voltage at the exit of the phase meter, Dsr1 and phase shifts when the signal passes through the flow against

him, K - coefficient of proportionality.

The resulting voltage, which is the difference between the voltages f / i and f / 2 and characterizes the flow velocity in known devices, depends, however, not only on the magnitude of this velocity, but also on the speed of sound, i.e., on physical parameters environment (density, temperature).

The exclusion of the influence of the speed of sound in the proposed device is based on the subtraction of values inversely proportional to the phase shifts. To do this, a two-channel transducer 6 is introduced into the device, which provides for obtaining a hyperbolic dependence of the output quantity on the input.

The voltages f / i and t / 2 at the output of the phase meter 5, as mentioned above, are proportional to the phase shifts, i.e.

J - and 17 g, LG 2

   C-V where: C - the speed of sound in the environment,

V is the flow rate of the latter,

KI - coefficient of proportionality.

These voltages are fed to the input of a two-channel converter 6, the channels of which are periodically connected to the phase meter 5 synchronously with the switching of the piezoelectric elements 2. The output of the voltage converter (or current), which is inversely proportional to the input voltage, can be achieved using nonlinear mechanical elements elements of the relevant profiles and other known methods.

At the output of converter 6, the signals are obtained:

„AH. K, (C-v) jr. (C-V)

 f / i to, and kg

the difference of which is:

i.e., the value is proportional to the flow velocity and does not depend on the physical parameters of the medium (temperature, density, etc.).

The summing device 7 can be graduated in units of speed or flow.

Subject invention

An ultrasonic device for measuring the flow rate in a pipeline, containing two piezoelectric elements located along the pipeline and periodically switched from transmission to reception, and a phase meter determining the phase shift between the emitted and received signals, in order to eliminate the influence of physical parameters ( temperature and density) of the medium; measurement accuracy; a two-channel transducer is connected to the output of the phase meter; it is switched synchronously with switching of the piezoelectric elements and converts output April voltage signals in phase meter is inversely proportional to respective phase shifts and supplied to a summing device.