Ultrasonic Temperature Measurement Research Articles

Design and analysis of sensor structure based on ultrasonic temperature measurement

Abstract Based on the principle of ultrasonic temperature measurement, this paper designs the structure of a waveguide rod sensor with a reflective groove. Using multi-physics field simulation software to conduct acoustic thermal coupling parametric simulation analysis on six different high melting point materials, we obtain the curve functions of the relationship between sound velocity and temperature for the six materials and verify the feasibility of ultrasonic temperature measurement using waveguide rods. Analysis shows that the sensitivity of six alloys to temperature changes is as follows: Ti6Al4V titanium alloy > α-Al2O3 > Inconel693 nickel-based alloy > ThO2 > Tungsten-rhenium alloy > Ta8W2Hf. At the same time, three different shapes of waveguide rods were designed: single groove waveguide rod, multi-zone waveguide rod, and spiral waveguide rod to analyze the impact of temperature measurement accuracy. The research results have important theoretical guidance significance for solving the problem of temperature measurement in high-temperature environments.

Real-Time Temperature Monitoring of Lithium Batteries Based on Ultrasonic Technology.

Electrochemical energy storage stations serve as an important means of load regulation, and their proportion has been increasing year by year. The temperature monitoring of lithium batteries necessitates heightened criteria. Ultrasonic thermometry, based on its noncontact measurement characteristics, is an ideal method for monitoring the internal temperature of lithium batteries. In this study, temperature and ultrasonic time delay measurement experiments were conducted on 18650 lithium batteries and laminated and wound lithium batteries to obtain the corresponding relationship between temperature and time delay and validate the temperature measurement for the same type of battery. The experimental results show that (1) the ultrasonic temperature measurement technique exhibits a relatively large error when used for 18650 Li-ion batteries under experimental conditions; (2) in the experiments on laminated and wound soft-pack lithium batteries, the relationship between temperature and time delay exhibits a nonlinear characteristic; and (3) under the experimental conditions, the ultrasonic temperature measurement errors were ±1.1 °C for stacked Li-ion batteries and ±1.4 °C for wound Li-ion batteries.

Research on key technology of ultrasonic temperature measuring instrument in high-temperature solid structure

Aiming at the key technical requirements of ultrasonic measurement of internal temperature of high temperature solid structure, firstly, the mechanical structure of ultrasonic transducer is miniaturized and high-temperature resistant design is carried out, so that it can withstand the high temperature of 800°C. Meanwhile, the multi-waveform, multi-channel and multi-frequency excitation detection is achieved, and the integration of structure and function is realized. In addition, the high-speed data acquisition module adopts a 1GSPS sampling rate acquisition card combined with the phase-based acoustic time integral zero sub-measurement method to achieve the nanosecond acoustic time measurement accuracy required by ultrasonic temperature measurement. Finally, the reconstructed internal temperature field of steel structure is carried out by using the developed electromagnetic ultrasonic temperature measuring instrument and compared with the temperature measuring result of thermocouple, which verifies the reliability of high temperature resistant electromagnetic ultrasonic probe and high-speed acquisition module. The research shows that the integration of ultrasonic temperature measurement technology and the design and development of instruments will provide effective analysis methods, research means and testing tools for exploring the internal temperature parameters of structures.

Ultrasonic measurement and methods for reconstruction of temperature fields for the use in bioreactors

Abstract When operating bioreactors, monitoring the process temperature is of great importance. Ultrasonic temperature measurement enables this without the need for sensors inside the bioreactor. The average speed of sound can be determined from the travel time of ultrasonic waves along the path of known length between a transmitter and a receiver positioned in the reactor wall. Due to the temperature dependence of the speed of sound, the average temperature along the path can be calculated from the average speed of sound. If this measurement is carried out for a sufficiently large number of measurement paths in a slice plane of the bioreactor, the temperature field in this plane can be reconstructed. In this article, a measurement setup for measuring temperature distributions is presented. Two different methods are then used to reconstruct temperature fields from the travel times measured with this setup. The first method is the Tikhonov regularization, which is widely used to solve inverse problems. The second method is derived from compressed sensing and can only be used under certain conditions. However, if these conditions are met, this method always provides better results than Tikhonov regularization. In addition to reconstruction results from measured travel times, results from simulated travel times are also presented.

Ultrasonic thermometric measurement system for solid rocket combustion chambers

Solid rocket motor (SRM) temperature is an important physical parameter for which there is no reliable in situ measurement device, apart from a thermocouple, for such a high temperature environment apart. In this study, an ultrasonic temperature measurement system was designed with an iridium-rhodium-40% alloy waveguide. Laboratory experiments showed that the device obtained ultrasonic signals up to 1800 °C with a temperature fitting curve from room temperature to 1800 °C. The thermometer also operated stably under high temperature and produced a repeatable calibration curve, at 97% repeatability. An error band was obtained with 95% confidence. At temperatures above 1000 °C, sensitivity gradually increased to a maximum of 0.0035 µs/°C. A corresponding application structure was established for an SRM before subjecting the sensor to a temperature test experiment. The temperature–time curve obtained detected a peak temperature at 1744 °C.

Ultrasonic measurement of air temperature along the axis of a laser beam during interferometric measurement of length

An ultrasonic technique that allows compensation of air temperature changes and gradients along the beam axis of the laser interferometer during displacement measurement is presented.The system is based on using two ultrasonic paths parallel to the laser beam that operate at different frequencies and continuous waves emitted in opposite directions. The theoretical basis of the measurements is presented. To enable ultrasonic temperature measurement when the measuring reflector is moving, an iterative measurement algorithm is proposed. Experimental assessment of the accuracy of the method is presented. The effect of air temperature gradients along the laser beam axis is tested. The influence of air flow on the measurement accuracy is analyzed.

Sensor data fusion for responsive high resolution ultrasonic temperature measurement using piezoelectric transducers

Ultrasonic temperature measurement allows for responsive measurements across an entire ultrasonic pathway, unlike most conventional temperature sensors that respond to the temperature at the point of their placement only after a notable response time. The high cost of required ultrasonic instrumentation can be reduced substantially by using ultrasonic oscillating temperature sensors (UOTS) consisting of inexpensive narrowband piezo transducers and driving electronics. An UOTS produces sustained oscillations at a frequency that relates to the temperature of the medium between the transducers. The existence of thermal hysteresis in UOTS readings, observed experimentally and apparently related to the fundamental properties of piezoelectric materials, makes conversion of the output frequency readings to the temperature values ambiguous. This makes it complicated to calibrate and use UOTS on their own. In the reported experiment (heating, then naturally cooling of a water vessel equipped with both UOTS and conventional sensors), this hysteresis was solved by fusing UOTS data with conventional temperature sensor readings. As the result, the combination of one UOTS plus one conventional reference sensor allowed improving both the temperature resolution and responsiveness of the latter and ambiguity of the readings of the former. Data fusion effectively led to calibrating the UOTS at every change of the conventional sensor's reading, removing any concerns related to the thermal expansion/contraction of the ultrasonic pathway itself and/or hysteresis of piezoelectric transducers.

Development of novel ultrasonic temperature measurement technology for combustion gas as a potential indicator of combustion instability diagnostics

In this study, a high-speed, fast responsive, non-intrusive ultrasonic thermometry system was proposed as a potential candidate for overcoming the disadvantages of thermocouples. The principle of this system is based on the thermal dependence of the speed of sound, and the temperature is measured by detecting the flight time of ultrasonic wave (USW) between the transmitter and the receiver. For a fast and exact measurement, the algorithm was developed as simple as possible, and the exact values of the physical properties, such as specific heat ratio and molecular weight of combustion gas, were taken from the computational calculation of CHEMKIN-Pro with GRI 3.0 mechanism. The performance of the system was verified by two experiments. First, the system was applied to measure the temperature of heated air. Results showed high precision with a 0.3% error when incorporating a modification equation and fast responsive dynamic performance, which directly reflect the rapid temperature change. Second, the combustion gas temperature above a multi-jet burner, which provides a horizontally uniform temperature distribution similar to a flat flame burner, was measured. Five different flame temperatures were measured using a thermocouple and an optic-based measurement method based on two-line atomic fluorescence (TLAF) as well as ultrasonic thermometry to compare their performances. Ultrasonic thermometry showed a slightly lower accuracy than those of TLAF and the thermocouple. This condition could be overcome by correcting the results using linear fitting, as the temperature measured by USW showed the best linearity among them. The USW technique showed excellent performance in terms of the measurement speed of 1000 samples/s and uncertainty under 0.73%. This USW thermometry of combustion gas can be applied to many combustion systems, including boilers and gas turbines. Specifically, fast temperature measurement at a speed of around 1 kHz enables the diagnosis of the combustion instability phenomenon, which is a difficult task when using conventional methods of temperature measurement. Furthermore, both dynamic pressure and temperature can be simultaneously measured at a high rate, thus synergistically increasing the accuracy of combustion instability diagnosis with sufficient information, such as the Rayleigh index or the flame transfer function.

Simple single transducer ultrasonic thermometer using electrostatic actuator

This article presents an experimental setup for the ultrasonic temperature measurement with a single acoustic transducer. The ultrasonic thermometer uses the simple impulse-echo method to determine the time of flight of short 75 kHz acoustic bursts travelling through a waveguide from which the velocity of sound and subsequently the temperature (of the environment surrounding the waveguide) is computed. The waveguide consists of 500 mm long stainless steel tube with an inner diameter of 22 mm, connected in series with a tube of the reduced diameter (10 mm, 171 mm long). The difference in cross sections of respective parts allows to determine sound velocity only in the segment of the thermometer which is fully immersed into the measured medium. The whole system is controlled by the NI LabVIEW application which uses the NI PXI system for both generating the signal for the electrostatic actuator and measuring the signal from the receiver part of the circuit. Implementation of the electrostatic actuator allows to use one acoustic transducer without the need of complex supporting electronics or time synchronisation between signals. All the signals representing the initial acoustic pulse and echoes from the waveguide are present in a single channel record. The temperature estimation is computed from basic signal parameters. The principle of the thermometer prototype operation and first calibration results in the temperature range of (−20 to 90) °C are shown. Results of calibration and subsequent interpolation applied on measured data show current limits of the thermometer.

A measurement system of high-temperature oxidation environment with ultrasonic Ir0.6Rth0.4 alloy thermometry

Iridium-rhodium is generally applied as a thermocouple material, with max operating temperature about 2150 °C. In this study, a ultrasonic temperature measurement system was designed by using Iridium-rhodium (60%Ir–40%Rh) alloy as an acoustic waveguide sensor material, and the system was preliminarily tested in a high-temperature oxidation environment. The result of ultrasonic temperature measurement shows that this system can indeed work stably in high-temperature oxidation environments. The relationship between temperature and delay time of ultrasonic thermometry up to 2200 °C was illustrated. Iridium-rhodium materials were also investigated in order to fully elucidate the proposed waveguide sensor’s performance in a high-temperature oxidation environment. This system lays a foundation for further application of high-temperature measurement.

Acoustic waveguides: An attractive alternative for accurate and robust contact thermometry

We report a robust and very precise method of measuring temperature using ultrasonic waves. Solid stainless steel waveguides are used to provide well-defined and stable ultrasonic wave propagation paths. Ultrasonic wave velocity is strongly temperature dependent. The arrival times of the ultrasonic wavepackets along a waveguide are used to infer the average temperature of the waveguide. Our ultrasonic temperature measurements exhibit a high precision (i.e. ±0.015 °C) that is more than two times better than the quoted accuracy of 1/10 DIN resistance temperature detectors (RTDs). The responsiveness of the waveguides was also investigated. While ultrasonic measurements can be made at very high frequencies, the responsiveness is limited by the heat transfer into the active sensing area. The waveguides make it easy to customise the dimension of the active sensing area and a shorter response time than those of RTDs has been demonstrated. The technique presented in this paper is a robust and cost effective alternative to other contact temperature measurements.

Multiple temperature sensors embedded in an ultrasonic “spiral-like” waveguide

This paper studies the propagation of ultrasound in spiral waveguides, towards distributed temperature measurements on a plane. Finite Element (FE) approach was used for understanding the velocity behaviour and consequently designing the spiral waveguide. Temperature measurements were experimentally carried out on planar surface inside a hot chamber. Transduction was performed using a piezo-electric crystal that is attached to one end of the waveguide. Lower order axisymmetric guided ultrasonic modes L(0,1) and T(0,1) were employed. Notches were introduced along the waveguide to obtain ultrasonic wave reflections. Time of fight (TOF) differences between the pre-defined reflectors (notches) located on the waveguides were used to infer local temperatures. The ultrasonic temperature measurements were compared with commercially available thermocouples.

Ultrasonic Al₂O₃ Ceramic Thermometry in High-Temperature Oxidation Environment.

In this study, an ultrasonic temperature measurement system was designed with Al2O3 high-temperature ceramic as an acoustic waveguide sensor and preliminarily tested in a high-temperature oxidation environment. The test results indicated that the system can indeed work stably in high-temperature environments. The relationship between the temperature and delay time of 26 °C–1600 °C ceramic materials was also determined in order to fully elucidate the high-temperature oxidation of the proposed waveguide sensor and to lay a foundation for the further application of this system in temperatures as high as 2000 °C.

Calibration Method of an Ultrasonic System for Temperature Measurement.

System calibration is fundamental to the overall accuracy of the ultrasonic temperature measurement, and it is basically involved in accurately measuring the path length and the system latency of the ultrasonic system. This paper proposes a method of high accuracy system calibration. By estimating the time delay between the transmitted signal and the received signal at several different temperatures, the calibration equations are constructed, and the calibrated results are determined with the use of the least squares algorithm. The formulas are deduced for calculating the calibration uncertainties, and the possible influential factors are analyzed. The experimental results in distilled water show that the calibrated path length and system latency can achieve uncertainties of 0.058 mm and 0.038 μs, respectively, and the temperature accuracy is significantly improved by using the calibrated results. The temperature error remains within ±0.04°C consistently, and the percentage error is less than 0.15%.

High-accuracy ultrasonic temperature measurement based on MLS-modulated continuous wave

Ultrasonic temperature measurement has the potential to improve measurement accuracy by increasing the length of a received signal due to its excellent performance with noise resistance. However, when the distance between the transmitter and receiver is limited, the received signal can be polluted by strong multiple echoes, which can significantly degrade temperature accuracy. This paper proposes a method for high-resolution ultrasonic temperature measurement. With the use of a maximum length sequence (MLS)-modulated continuous wave, the obstructive effect of echoes is effectively suppressed. A hybrid method is employed for accurate time-of-flight (TOF) estimation by incorporating both cross-correlation and phase shift (PS), which is the basis of highly accurate temperature measurement. The experimental results in distilled water show that the proposed method estimates TOF with a standard deviation of less than 0.3ns, and temperature errors consistently remain within ±0.04°C.

Ultrasonic thermometry for friction stir spot welding

This investigation presents the feasibility of ultrasonic temperature measurement of friction stir spot welding (FSSW). FSSW is an automated solid state joining process. Thermal profiles of the weld zone are crucial for implementing informed process changes to improve weld quality. Ultrasonics present a novel and non-invasive method of monitoring changes in temperature.Ultrasonic time of flight (TOF) measurement method is used to calculate the temperature of Al 6061 as it is heated. Comparisons of the ultrasonic temperature calculations with thermocouple readings confirm the accuracy of the ultrasonic system. The ultrasonic signal is then recorded during spot welding and processed. The results show that ultrasonic technology is a feasible method of monitoring the heating and cooling profiles of the weld zone during welding. The paper also discusses challenges presented by the system as well as recommendations for its future implementation in the friction stir welding manufacturing industry.

Design of Ultrasonic Gas Temperature Measurement System with Humidity Self-Correction

In the ultrasonic gas temperature measurement system, the principle is that the velocity of sound in gas is a function of temperature. But because the propagation speed of ultrasonic wave can be easily affected by humidity, the accuracy of the gas temperature measurement will be affected too. This dissertation will implement the ultrasonic gas temperature measurement system with humidity correction suitable for all kinds of environment humidity. This type of ultrasonic technique is a highly efficient algorithm with the advantages of both time-of-flight method and phase shift method. And the system is realized with a single-chip microcomputer-based with a relative humidity/water vapor pressure meter. The main advantages of this ultrasonic temperature measurement system are high resolution, using narrow-bandwidth ultrasonic transducer of low cost and ease of implementation.

Application of the Block Correction Interpolation Technology in the Ultrasonic Temperature Measurement

A new method about the air temperature reconstruction based on the block correction interpolation was put forward. Its theoretical basis is the principles of thermodynamics relations and ultrasonic temperature measurement. The frequency of ultrasonic generator is 40 KHz. Because of the one-to-one relationship between gas temperature and gas velocity, the gas temperature field can be reconstructed through the rebuilding of velocity field. As the distance between the generator and receiver is known, so the average speed on the path can be obtained by detecting the ultrasonic transit-time. After obtaining the average speed of many paths in the field, the correction of the measured data can be done by using the block correction interpolation technology. And through the mathematical analysis software, the reconstruction of the measured field was given.

Ultrasonic Measurements of Temperature in Aqueous Solutions: Why and How

The paper describes two different approaches to ultrasonic measurements of temperature in aqueous solutions. The first approach uses two narrowband ultrasonic transducers and support electronics that form an oscillating sensor which output frequency is related to the measured temperature. This low-cost sensor demonstrated sensitivity of about 40 Hz/K at the distance of 190 mm and the operating frequency of about 25 kHz. The second approach utilised pulse-echo mode at the centre frequency of 20 MHz. The reflector featured a cavity that was filled with deionised water. The ultrasound propagation delay in the cavity was related to the temperature in the solution. The experiments were conducted for deionised water, and solutions of sodium persulfate, sodium chloride, and acetic acid with concentrations up to 0.5 M. In the experiments (conducted within the temperature range from 15 to 30°C), we observed increases in the ultrasound velocity for increased temperatures and concentrations as was expected. Measurement results were compared with literature data for pure and seawater. It was concluded that ultrasonic measurements of temperature were conducted with the resolution well below 0.1 K for both methods. Advantages of ultrasonic temperature measurements over conventional thermometers were discussed.

3-08P-32 Thermal property reconstructions on the basis of ultrasonic temperature measurements : How to deal with perfusion and thermal source(Poster session 3)

3-08P-32 Thermal property reconstructions on the basis of ultrasonic temperature measurements : How to deal with perfusion and thermal source(Poster session 3)