Thermodynamic temperature measurement device and method for synchronous measurement of multiple acoustic resonance frequencies

Abstract

The present invention discloses a thermodynamic temperature measurement device and method for synchronous measurement of multiple acoustic resonance frequencies. The signal generation module generates two or more sinusoidal voltage signals of different frequencies at the same time. After mixing and enhancement, the acoustic transducer generates sound waves of the same frequency as each sinusoidal voltage signal through mechanical vibration. The sound waves establish a sound field in the acoustic resonance cavity, so that the gas inside the acoustic resonance cavity generates vibrations of the corresponding frequency to achieve resonance. After the acoustic receiver is converted into a voltage signal, the signal demodulation module performs demodulation, and the signal processing module processes the demodulated signal to obtain the corresponding acoustic resonance frequency signal, and further calculates and obtains the corresponding thermodynamic temperature measurement result, thereby obtaining the final thermodynamic temperature measurement result. The present invention significantly accelerates the efficiency of measuring thermodynamic temperature by gas acoustic method by simultaneously performing excitation and measurement of two or more acoustic resonance frequencies while ensuring the measurement signal-to-noise ratio.

Description

Technical Field

[0001] The present invention relates to the technical field of gas acoustic temperature measurement, and in particular to a thermodynamic temperature measurement device and method for synchronously measuring multiple acoustic resonance frequencies. Background Art

[0002] The gas acoustic primary temperature measurement method can obtain accurate thermodynamic temperature in a laboratory environment, which is used for understanding physical reality and revising the international temperature scale. On the other hand, it can achieve zero traceability of temperature in special scenarios, that is, calibration-free measurement. The measurement speed is one of the key factors in developing a practical gas acoustic primary temperature measurement method. Improving the efficiency of this method in thermodynamic temperature measurement so that it can meet the measurement time requirements of field measurements can lay an important foundation for its further widespread use.

[0003] The gas acoustic primary temperature measurement method is based on the thermodynamic relationship of the sound velocity of the gas (usually a monatomic gas). The gas sound velocity is obtained by measuring the acoustic resonance frequency of the gas in a resonant cavity (usually a sphere or cylinder) and combining it with the cavity size. Due to the influence of the boundary layer effect of the gas in the cavity, shell vibration, non-ideal factors of the cavity geometry, etc., there are certain differences in the measurement of acoustic resonance frequencies of different modes, and it is usually necessary to measure the acoustic resonance frequencies of multiple modes. The general measurement method is to measure the acoustic resonance frequency of a single mode one by one, so the measurement time of a single temperature point is relatively long, which is limited in practical application. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention aims to provide a thermodynamic temperature measurement device and method for synchronously measuring multiple acoustic resonance frequencies.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A thermodynamic temperature measuring device for synchronously measuring multiple acoustic resonance frequencies, comprising a signal generating module, a frequency mixing module, a voltage amplifier, an acoustic resonance chamber, an acoustic transducer, an acoustic receiver, a signal demodulation module and a signal processing module;

[0007] The signal generating module is used to simultaneously generate two or more sinusoidal voltage signals of different frequencies; the sinusoidal voltage signals of different frequencies are used to synchronously measure the acoustic resonance frequency of each acoustic mode;

[0008] The mixing module is used to mix and filter the sinusoidal voltage signals generated by the signal generating module, and add them together to obtain a mixed voltage signal;

[0009] The voltage amplifier is used to enhance the voltage signal;

[0010] The interior of the acoustic resonance chamber is filled with gas, and the acoustic transducer and the acoustic receiver are respectively installed on the upper end cover and the lower end cover of the acoustic resonance chamber; the acoustic transducer is used to receive the voltage signal increased by the voltage amplifier, and generate sound waves with the same frequency as each sinusoidal voltage signal through mechanical vibration. The sound waves establish a sound field in the acoustic resonance chamber, so that the gas inside the acoustic resonance chamber generates vibrations of the corresponding frequency to achieve resonance, and the resonance frequency changes with the temperature of the gas; the acoustic receiver is used to receive the sound pressure signal generated by the gas inside the acoustic resonance chamber, and convert the sound pressure signal into a voltage signal;

[0011] The signal demodulation module is used to receive each sinusoidal voltage signal output by the signal generation module and the voltage signal output by the acoustic receiver, and use each sinusoidal voltage signal as a frequency reference to demodulate the voltage signal emitted by the acoustic receiver, and extract and separate the useful signals of multiple acoustic modes from the noise interference respectively;

[0012] The signal processing module is used to process the useful signals of various acoustic modes demodulated by the signal demodulation module to obtain corresponding acoustic resonance frequency signals, respectively. The signal frequency range of each acoustic resonance frequency signal is the same as the sweep frequency range of each sinusoidal voltage signal; the signal processing module calculates each acoustic resonance frequency signal to obtain the corresponding thermodynamic temperature measurement result, and performs weighted average on each thermodynamic temperature measurement result to obtain the final thermodynamic temperature measurement result.

[0013] Furthermore, the acoustic transducer is a piezoelectric ceramic transducer, and the acoustic receiver is a piezoelectric ceramic transducer or a microphone.

[0014] The present invention also provides a thermodynamic temperature measurement method using the multi-acoustic resonance frequency synchronous measurement of the above device, the specific process is:

[0015] The signal generating module generates two or more sinusoidal voltage signals with different frequencies simultaneously;

[0016] The mixing module mixes and filters each sinusoidal voltage signal generated by the signal generating module, and adds them together to obtain a mixed voltage signal;

[0017] The voltage amplifier amplifies the voltage signal;

[0018] The acoustic transducer receives the voltage signal increased by the voltage amplifier, and generates sound waves of the same frequency as each sinusoidal voltage signal through mechanical vibration. The sound waves establish a sound field in the acoustic resonance chamber, causing the gas inside the acoustic resonance chamber to vibrate at the corresponding frequency to achieve resonance. The resonance frequency changes with the temperature of the gas. The acoustic receiver receives the sound pressure signal generated by the gas inside the acoustic resonance chamber and converts the sound pressure signal into a voltage signal.

[0019] The signal demodulation module receives each sinusoidal voltage signal output by the signal generation module and the voltage signal output by the acoustic receiver, uses each sinusoidal voltage signal as a frequency reference, demodulates the voltage signal emitted by the acoustic receiver, and extracts and separates the useful signals of multiple acoustic modes from the noise interference respectively;

[0020] The signal processing module processes the useful signals of multiple acoustic modes demodulated by the signal demodulation module to obtain corresponding acoustic resonance frequency signals respectively;

[0021] The signal processing module calculates each acoustic resonance frequency signal to obtain a corresponding thermodynamic temperature measurement result, and performs weighted average on each thermodynamic temperature measurement result to obtain a final thermodynamic temperature measurement result.

[0022] The beneficial effects of the present invention are as follows: the present invention proposes a device and method for synchronously measuring multiple acoustic resonance frequencies. By simultaneously exciting and measuring more than two acoustic resonance frequencies, while ensuring the measurement signal-to-noise ratio, the efficiency of measuring thermodynamic temperature by the gas acoustic method can be significantly accelerated, effectively solving the problem of long measurement time of the gas acoustic temperature measurement method. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a structural principle diagram of the thermodynamic temperature measurement device in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to this embodiment.

[0025] Example 1

[0026] This embodiment provides a thermodynamic temperature measurement device for synchronously measuring multiple acoustic resonance frequencies, such as Figure 1 As shown, it includes a signal generating module 1 , a mixing module 4 , a voltage amplifier 6 , an acoustic resonance chamber 7 , an acoustic transducer 8 , an acoustic receiver 9 , a signal demodulation module 10 and a signal processing module 11 .

[0027] The signal generating module 1 is used to simultaneously generate two or more sinusoidal voltage signals with different frequencies (such as Figure 1 The first sinusoidal voltage signal 2 and the second sinusoidal voltage signal 3 shown); the sinusoidal voltage signals of different frequencies are used to synchronously measure the acoustic resonance frequency (acoustic resonance frequency acoustic resonance frequency) of each acoustic mode.

[0028] Usually, when measuring the acoustic resonance frequency, the theoretical resonance frequency and half-width of the gas in the acoustic resonance chamber at the set temperature are calculated, and then the frequency sweep range is obtained by adding or subtracting n times the half-width from the theoretical resonance frequency. Several measurement frequencies are evenly selected within the frequency sweep range, and the sinusoidal voltage signal of the output measurement frequency is measured. The acoustic resonance frequencies of different acoustic modes are approximately integer multiples, and the same number of measurement frequencies are selected within the frequency sweep range, so the frequencies of the first sinusoidal voltage signal 2 and the second sinusoidal voltage signal 3 are approximately integer multiples.

[0029] The mixing module 4 is used to mix and filter the sinusoidal voltage signals generated by the signal generating module 1 , and add them together to obtain a mixed voltage signal 5 .

[0030] The voltage amplifier 6 is used to enhance the voltage signal 5 .

[0031] The acoustic resonance cavity 7 is filled with a certain amount of gas, and the acoustic transducer 8 and the acoustic receiver 9 are respectively installed on the upper end cover and the lower end cover of the acoustic resonance cavity 7; the acoustic transducer 8 is used to receive the voltage signal increased by the voltage amplifier 6, and generate sound waves with the same frequency as each sinusoidal voltage signal through mechanical vibration. The sound waves establish a sound field in the acoustic resonance cavity 7, so that the gas inside the acoustic resonance cavity 7 generates vibrations of the corresponding frequency to achieve resonance, and the resonance frequency changes with the temperature of the gas; the acoustic receiver 9 is used to receive the sound pressure signal generated by the gas inside the acoustic resonance cavity 7, and convert the sound pressure signal into a voltage signal. The acoustic transducer 8 and the acoustic receiver 9 can both use piezoelectric ceramic transducers, and the acoustic receiver 9 can also use a microphone, etc.

[0032] The signal demodulation module 10 is used to receive each sinusoidal voltage signal output by the signal generating module 1 and the voltage signal output by the acoustic receiver 9, and uses each sinusoidal voltage signal as a frequency reference to demodulate the voltage signal emitted by the acoustic receiver 9, and extract and separate the useful signals of multiple acoustic modes from the noise interference, thereby effectively improving the measurement signal-to-noise ratio.

[0033] The signal processing module 11 is used to process the useful signals of various acoustic modes demodulated by the signal demodulation module 10, and obtain corresponding acoustic resonance frequency signals (such as Figure 1 The first acoustic resonance frequency signal 12 and the second acoustic resonance frequency 13 are shown, and the signal frequency range of each acoustic resonance frequency signal is the same as the sweep frequency range of each sinusoidal voltage signal; the signal processing module 11 calculates each acoustic resonance frequency signal to obtain the corresponding thermodynamic temperature measurement result, and performs weighted average on each thermodynamic temperature measurement result to obtain the final thermodynamic temperature measurement result.

[0034] like Figure 1As shown, the first acoustic resonance frequency signal 12 and the second acoustic resonance frequency signal 13 are acoustic signals generated by mixing the first sinusoidal voltage signal 2 and the second sinusoidal voltage signal 3 and applying them to the acoustic transducer 8. After the acoustic signals resonate with the gas at a set temperature inside the acoustic resonance chamber 7, the acoustic resonance frequency measurement results obtained by the acoustic receiver 9. The first acoustic resonance frequency signal 12 and the second acoustic resonance frequency signal 13 are also approximately in a multiple relationship. The resonant frequencies of the first acoustic resonance frequency signal 12 and the second acoustic resonance frequency signal 13 can be calculated to obtain the thermodynamic temperature measurement results respectively. Generally, the deviation between the two temperature measurement results is small, and the final thermodynamic temperature measurement result can be obtained by weighted average calculation.

[0035] The above device can be used for simultaneous measurement of more than two acoustic resonance frequencies. However, when used for simultaneous measurement of more than two acoustic resonance frequencies, the voltage tolerance of the acoustic transducer needs to be considered.

[0036] Example 2

[0037] This embodiment provides a thermodynamic temperature measurement method using the multi-acoustic resonance frequency synchronous measurement of the device described in Embodiment 1, and the specific process is as follows:

[0038] The signal generating module 1 generates two or more sinusoidal voltage signals with different frequencies simultaneously;

[0039] The mixing module 4 mixes and filters the sinusoidal voltage signals generated by the signal generating module 1, and adds them together to obtain a mixed voltage signal 5;

[0040] The voltage amplifier 6 enhances the voltage signal 5;

[0041] The acoustic transducer 8 receives the voltage signal increased by the voltage amplifier 6, and generates sound waves of the same frequency as each sinusoidal voltage signal through mechanical vibration. The sound waves establish a sound field in the acoustic resonance chamber 7, so that the gas inside the acoustic resonance chamber 7 generates vibrations of the corresponding frequency to achieve resonance. The resonance frequency changes with the temperature of the gas. The acoustic receiver 9 receives the sound pressure signal generated by the gas inside the acoustic resonance chamber 7, and converts the sound pressure signal into a voltage signal.

[0042] The signal demodulation module 10 receives each sinusoidal voltage signal output by the signal generation module 1 and the voltage signal output by the acoustic receiver 9, uses each sinusoidal voltage signal as a frequency reference, demodulates the voltage signal emitted by the acoustic receiver 9, and extracts and separates the useful signals of multiple acoustic modes from the noise interference respectively;

[0043] The signal processing module 11 processes the useful signals of the various acoustic modes demodulated by the signal demodulation module 10 to obtain corresponding acoustic resonance frequency signals respectively;

[0044] The signal processing module 11 calculates each acoustic resonance frequency signal to obtain a corresponding thermodynamic temperature measurement result, and performs weighted average on each thermodynamic temperature measurement result to obtain a final thermodynamic temperature measurement result.

[0045] For those skilled in the art, various corresponding changes and modifications can be made according to the above technical solutions and concepts, and all of these changes and modifications should be included in the protection scope of the claims of the present invention.

Claims

1. A thermodynamic temperature measuring device for synchronous measurement of multiple acoustic resonance frequencies, characterized in that: It includes a signal generation module, a frequency mixing module, a voltage amplifier, an acoustic resonance chamber, an acoustic transducer, an acoustic receiver, a signal demodulation module and a signal processing module; The signal generating module is used to simultaneously generate two or more sinusoidal voltage signals of different frequencies; the sinusoidal voltage signals of different frequencies are used to synchronously measure the acoustic resonance frequency of each acoustic mode; The mixing module is used to mix and filter the sinusoidal voltage signals generated by the signal generating module, and add them together to obtain a mixed voltage signal; The voltage amplifier is used to enhance the voltage signal; The interior of the acoustic resonance chamber is filled with gas, and the acoustic transducer and the acoustic receiver are respectively installed on the upper end cover and the lower end cover of the acoustic resonance chamber; the acoustic transducer is used to receive the voltage signal increased by the voltage amplifier, and generate sound waves with the same frequency as each sinusoidal voltage signal through mechanical vibration. The sound waves establish a sound field in the acoustic resonance chamber, so that the gas inside the acoustic resonance chamber generates vibrations of the corresponding frequency to achieve resonance, and the resonance frequency changes with the temperature of the gas; the acoustic receiver is used to receive the sound pressure signal generated by the gas inside the acoustic resonance chamber, and convert the sound pressure signal into a voltage signal; The signal demodulation module is used to receive each sinusoidal voltage signal output by the signal generation module and the voltage signal output by the acoustic receiver, and use each sinusoidal voltage signal as a frequency reference to demodulate the voltage signal emitted by the acoustic receiver, and extract and separate the useful signals of multiple acoustic modes from the noise interference respectively; The signal processing module is used to process the useful signals of multiple acoustic modes demodulated by the signal demodulation module to obtain corresponding acoustic resonance frequency signals, and the signal frequency range of each acoustic resonance frequency signal is the same as the sweep frequency range of each sinusoidal voltage signal; The signal processing module calculates each acoustic resonance frequency signal to obtain a corresponding thermodynamic temperature measurement result, and performs weighted average on each thermodynamic temperature measurement result to obtain a final thermodynamic temperature measurement result.

2. The device according to claim 1, characterized in that The acoustic transducer adopts a piezoelectric ceramic transducer, and the acoustic receiver adopts a piezoelectric ceramic transducer or a microphone.

3. A thermodynamic temperature measurement method using the multi-acoustic resonance frequency synchronous measurement of the device according to any one of claims 1-2, characterized in that: The specific process is: The signal generating module generates two or more sinusoidal voltage signals with different frequencies simultaneously; The mixing module mixes and filters each sinusoidal voltage signal generated by the signal generating module, and adds them together to obtain a mixed voltage signal; The voltage amplifier amplifies the voltage signal; The acoustic transducer receives the voltage signal increased by the voltage amplifier, and generates sound waves of the same frequency as each sinusoidal voltage signal through mechanical vibration. The sound waves establish a sound field in the acoustic resonance chamber, causing the gas inside the acoustic resonance chamber to vibrate at the corresponding frequency to achieve resonance. The resonance frequency changes with the temperature of the gas. The acoustic receiver receives the sound pressure signal generated by the gas inside the acoustic resonance chamber and converts the sound pressure signal into a voltage signal. The signal demodulation module receives each sinusoidal voltage signal output by the signal generation module and the voltage signal output by the acoustic receiver, uses each sinusoidal voltage signal as a frequency reference, demodulates the voltage signal emitted by the acoustic receiver, and extracts and separates the useful signals of multiple acoustic modes from the noise interference respectively; The signal processing module processes the useful signals of multiple acoustic modes demodulated by the signal demodulation module to obtain corresponding acoustic resonance frequency signals respectively; The signal processing module calculates each acoustic resonance frequency signal to obtain a corresponding thermodynamic temperature measurement result, and performs weighted average on each thermodynamic temperature measurement result to obtain a final thermodynamic temperature measurement result.

Images