SU1377622A1 - Method of determining temperature - Google Patents

Abstract

This invention relates to a technique for measuring temperature. The purpose of the invention is to improve the accuracy and improve the spatial resolution in determining the temperature of the medium. With a change in temperature, the length of the sound wave passing through the medium changes, and hence the diffraction divergence of the wave. The ratio of the amplitude of the spherical wave to the amplitude of the plane wave arriving at the receiver is an unambiguous function of temperature. 3 il ..

Description

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The invention relates to a technique for measuring temperature and can be used to measure the temperature of gaseous media up to 5,000 K.

The purpose of the invention is to increase the accuracy and improve the spatial resolution in determining the temperature of the medium.

The essence of the invention is to conduct. With a change in temperature, the length of the sound wave passing through the medium changes, and hence the diffraction divergence of the wave. The ratio of the amplitude of the spherical wave to the amplitude of the plane wave S arriving at the receiver is an unambiguous function of temperature.

Fig. 1 shows a diagram of a device 5 implementing the proposed method in Fig. 2 — the dependence of the ratio of the amplitude of a spherical wave to the amplitudes of a plane wave on the distance between the emitter and receiver and on the speed of sound. In Fig. 3, the temperature of the medium versus A: AJJ amplitudes of spherical and plane waves at a reference temperature; A and A are the amplitudes of the spherical and plane waves at the measured temperature,.

The device contains a series-connected synchro generator 1, a generator 2 modulating-p: pulses, a modulator 3, an ultrasound OBOD radiator 4, an ultrasonic receiver 5, an amplifier 6, a trigger 7, keys 8-11, filling generators 12 and 13, amplitude detectors 14 and 15j digital indicators 16 and 18, analog-to-digital converters 17 and 19.

The device works as follows about

The synchronous generator 1 generates sync pulses with a repetition period T, which are fed to the input of the trigger 7 and the generator 2 of modulating pulses, which in each case has rectangular pulses of duration

These pulses arrive at the first input of the modulator 3. Depending on the position of the trigger 7, keys 8 and 10 are open and keys 9 and 11 are closed or vice versa. Accordingly, the second input of the modulator receives signals from the output of the generator 12 of the filling oscillations with a frequency F, through the key 8 or from the generator 13 of the oscillations filling

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Nen with a frequency of F through the key 9. Moreover, F 5 F ,. From the output of the modulator 3, the radio pulses are fed to the ultrasound emitter 1, which radiates an ultrasonic radio pulse to the medium under study. Frequencies F ", F are chosen such that at frequency F, a spherical ultrasonic wave is emitted, and when F is flat, the Ultravoltage receiver 5 receives an ultrasonic pulse, converts it into an electric one, which is amplified by amplifier 6 and fed to the inputs of keys 0 and 11. The radio pulse, depending on the position of the trigger 7, passes through the key 10 or 11 and goes to the input of one of the amplitude detectors 14 or 15 "From the output of the amplitude detector, the signal goes to the input of analog-to-digital converters 17 and 19, from the output of which digital information the amplitude of the signal applied to the corresponding digital indicator 16 or 18. Each of syn- hroi1u pulse varies mode radiation of ultrasonic waves. The mode of emission and amplitude measurement of spherical waves alternates with the mode of emission and amplitude measurement of plane ultrasonic waves. Measurements are carried out at known and measured temperatures of the gaseous medium; the readings of indicators 16 and 18, respectively A, A and A, A, are recorded. The temperature of the gas is judged by the dependencies (Fig. 3). The device uses ultrasonic rectangular transducers with 4x2 mm sides. The distance 7 between the converters is A mm. Dependence of the ratio of the average pressure P of a spherical wave to the average pressure P of a plane. waves from distance Z and -speed C of ultrasound in air at a frequency of F 250 kHz (FIG. 2), calculated from the Relay integral for 42 mm rectangular transducers, shows that the amplitude of a spherical wave with a change in the ultrasound velocity (gas temperature) at a fixed the distance between the transducers varies significantly. If at a known temperature (290 K) we denote it by Hell, then the normalized amplitude of the spherical wave A / A varies in the range from 0.433001 to 1 when the temperature changes from 290 - 5600 K. On this basis, the temperature dependence is shown in FIG. gas (air) as a function of the amplitude ratio A / Ad / A / A, from which the gas temperature is determined. The repetition period of the clock pulses (T) is. The modulating pulse generator produces pulses with a duration of, which is selected from the condition

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The value of the ultrasound velocity in the gas at the maximum temperature. For air at a temperature of 5600 K 1500 m / S; 8 μs This condition excludes the possibility of the occurrence of standing waves between the emitter and receiver. The frequencies of the signals generated by the oscillators 12 and 13 of the filling oscillations (F 250 kHz and F 1.25 MHz) are selected from the conditions of radiation by an ultrasonic emitter of spherical and plane waves, respectively. The ultrasonic emitter, in the mode of radiation of spherical waves, is excited by a radio pulse with a filling frequency F, 250 kHz in the first thickness mode, and in the mode of emission of a Flat wave with a filling frequency F of 1.25 M, in the fifth thickness

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fashion The amplitudes of the received ultrasonic radio pulses at the measured temperature of both spherical and plane ultrasonic waves are normalized to the corresponding amplitudes at a known gas temperature in order to eliminate temperature measurement errors due to different transmission coefficients of the electroacoustic path at different frequencies P. and F, as well as due to change 1

no acoustic impedance of gas with a change in the temperature of the medium. Therefore, the device is invariant with respect to changing measurement conditions.

Claims (1)

Invention Formula The method of determining the temperature by sounding the medium by sound waves, characterized in that, in order to increase the accuracy and improving the spatial resolution, the medium is probed with flat and spherical sound waves, the measurement of their amplitudes and the temperature of the medium are determined from the ratio of the measured amplitudes. a 12 g, MP ttm t sum that O.CH U, S ejS 0.7 g, S 0.3 A I tPuf.S A j