Open AccessHigh-precision nuclear-quadrupole-resonance thermometer for aerohydrodynamic research
Author(s) -
Т. М. Ткаченко,
Y. Pilkеvych,
V. Mileikovskyi
Publication year - 2020
Publication title -
ventilâcìâ, osvìtlennâ ta teplogazopostačannâ
Language(s) - English
Resource type - Journals
eISSN - 2664-5769
pISSN - 2409-2606
DOI - 10.32347/2409-2606.2020.35.34-40
Subject(s) - comparator , thermometer , signal (programming language) , amplifier , band pass filter , spectrometer , physics , materials science , electrical engineering , voltage , optoelectronics , optics , computer science , engineering , cmos , quantum mechanics , programming language
In hydroaerodynamics, there are problems that require increased accuracy of temperature measurement. An example is the measurement of excess temperature at the periphery of turbulent jets. Unlimited temperature increase on the axis of the jet to increase the accuracy of measurement is impractical due to non-automodeliness by the Archimedes number. To do this, it is possible to use the phenomenon of nuclear quadrupole resonance. The device for exact measurement of temperature in the range from 0° C to +200 °C is offered. Using the LabView graphic programming package, a virtual model of an automatic thermometer based on nuclear quadrupole resonance in КClO3 was built. The temperature sensor is a superregenerative spectrometer with automatic monitoring of the center of the absorption line of the thermometric substance, consisting of the actual superregenerator, bandpass filter, comparator, DC amplifier and modulating voltage generator. The circuit that switches the supergenerator to the mode of continuous generation and output of information on the display contains a single vibrator, a buffer stage, a microcontroller and an indicator. From the output of the superregenerator, the absorption signal is fed to the bandpass filter, and then to the comparator. After the comparator, a voltage equal to the input voltage difference is amplified by a DC amplifier. This signal controls the resonant absorption frequency through the feedback circuit. The frequency of the sensor polling is determined by a single vibrator, the oscillations of which are synchronized with the clock generator. Measuring uncertainty in the range above changes from 0.02 K to 0.002 K It has been shown that either a manual frequency measurement method or a regenerative mode must be used to reduce the measurement uncertainty up to 0.002 K in the range. This improved automatic device is more complex, because of requirements of special measures to eliminate parasitic amplitude modulation. To increase the temperature range and precision, it is possible to find other thermometric substance, such as Сu2O crystals.