SU917092A1 - Device for hot-wire anemometer graduation - Google Patents

Description

(S) DEVICE FOR GRADING A THERMO-ANEMOMETER

This invention relates to measurable. technical equipment, namely, devices for calibration of thermoanemometers.

A device for calibrating a hot-wire anemometer, consisting of a measuring circuit with a hot-wire anemometer, setters of velocity and gas flow temperature, a data processing unit ij, is known.

The closest in technical essence to the proposed property. . a device for graduating a thermryemometer containing a flow parameter setting unit, a sensitive element included in a bridge circuit, to the supply diagonal of which an alternating electrical signal source is connected, and the measuring diagonal is connected through an AC amplifier, detector, low-pass filter, DC amplifier with a recorder 23) The disadvantage of this device is 4to, it has a significant measurement error associated with the temperature change being investigated th gas stream.

The purpose of the invention is to increase accuracy and speed.

To achieve this goal, the device for the calibration of the hot-wire anemometer is equipped with an analog-digital

10 by a converter, a computing unit, and at least two conversion circuits connected between the output of the AC amplifier and the analog-to-digital converter,

15 connected via a computing unit with the recorder's output, while the source of the alternating electrical signal is made as a source of a polyharmonic signal, through

Claims (2)

20 which is connected to a DC amplifier in series with a polyharmonic source and to the supply diagonal of the bridge circuit, each of the conversion circuits consisting of a bandpass filter, a tuner, a low pass filter, and a DC amplifier. The drawing shows the structures on the scheme of the calibration of the hot-wire anemometer. The measuring circuit contains an adjustable source of 1 rectangular pulses, included in a bridge circuit with a sensing element 2. An alternating current amplifier 3 is connected to the measuring diagonal of the bridge circuit, to which conversion circuits from series-connected detector k, low-pass filter 5 and amplifier 6 are connected. nnogo current. In addition, conversion circuits are connected to the output of the ac amplifier 3, each of which consists of series-connected band-pass filters of detectors 10–12 and low-pass filters of amplifiers 16–18 of direct current. Conversion circuits are connected via an analog-to-digital converter 19 to a computing unit 20, having at its output a recorder 21, calibrated according to measured pairs | tram The sensing element 2 of the hot-wire anemometer is blown by the gas flow from the setpoint 22 of speed and temperature. A DC amplifier 6 is connected by a feedback circuit with an adjustable source of rectangular pulses T and recorder 2. A device for calibrating a hot-wire anemometer works as follows. A source of 1-square pulses creates a polyharmonic signal at the output of an electrical circuit with a sensitive element 2 of a hot-wire anemometer. AC amplifier 3 is used to amplify the voltage from the measuring diagonal of the bridge resistance. Band-pass filters serve as a selection of different harmonics. Detectors 10 and 11 and low pass filters 13–15 pick out these harmonic envelopes in narrow frequency bands cut by band pass filters. Low voltage filter voltages are fed after dc amplifiers 1618 to analog-to-digital converter 19 and further to computing unit 20. In computing unit 20, the incoming signals are processed in accordance with the data on the calibration dependences of the amplitudes of the harmonics on the measured parameters. Registrar 21 records information about the measured parameters V (speed) and T (temperature). . The conversion target, consisting of a series-connected detector k, a low-pass filter 5 and a DC amplifier 6, which is connected to the controlled square pulse generator 1, maintains the temperature of the constant sensor 2 ,. A device for calibrating a hot-wire anemometer improves the accuracy and reliability of measuring the speed with a hot-wire anemometer under the CONDITIONS of changing the temperature of the gas stream, thereby expanding its scope. In addition, the device makes it possible to measure simultaneously the velocity and temperature of the gas stream with one sensitive element. The invention The device for the calibration of the hot-wire anemometer, containing a flow parameter setting unit, a sensitive element included in a bridge circuit, to the supply diagonal of which an alternating electrical source is connected. The signal is dialed through an AC amplifier, detector, low-pass filter, DC amplifier with the recorder and covered by a feedback circuit, which is designed to increase accuracy and speed. equipped with an analog-to-digital converter, a computing unit, and at least two conversion circuits connected between the output of an AC amplifier and an analog-to-digital converter connected via a computing unit with the output of the recorder, while the source of the alternating electrical signal is a polyharmonic source, and the DC amplifier is connected in series with the source of the polyharmonic signal and with the supply diagonal of the bridge circuit. each of the conversion chains consists of a bandpass filter, a detector; low pass filter and dc amplifier. Sources of information taken into account during the examination 17092 1. Bradshaw P. Introduction to turbulence and its measurement. World, 197, with. 208-209. 2.Strickert N., Hitzdraht und HitxfiImanemometrie. VEB VERLAGTECHNIK, BERLIN, 197t, c, 173 (prototype).