Ultrasonic Gas Research Articles

Industrial leak testing of dangerous goods packagings

The Dangerous Goods Regulations currently do not include limit leakage rates or sensitivity requirements for industrial leak testing procedures that are equivalent to the bubble test, which is the prescribed test method for design type testing of dangerous goods packagings. During series production of such packagings, various methods are used, which often do not meet the requirements of the bubble test with regard to important criteria.Sensitivity, flow direction, pressure level and automatability are particularly important factors when selecting a suitable industrial leak testing method.The following methods are in principle both suitable and equally effective as the bubble test: pressure rise test (vacuum chamber), ultrasonic bubble leak detection and gas detection methods (pressure technique by accumulation and vacuum chamber technique).To ensure a uniform test level during design type testing and production line leak testing and therefore a comparable safety level as required by the Dangerous Goods Regulations, it is necessary to include a more precise specification in these regulations. This requires, on the one hand, information about the sensitivity of the bubble test and, on the other hand, the inclusion of a list of suitable, equally effective industrial test methods with their specific boundary conditions.

Universality of the Principle of Sufficiency for Ultrasonic Technologies in Liquid Media

Using an ultrasonic technology as an example, we showed the validity and universality of the principle of sufficiency proposed by Dobatkin for various economics fields. A 25-mm-thick compacted material having no solid granules is fabricated when a stream of a molten grade 1973 alloy with high transition metal contents (0.63% Zr, 0.27% Cr, 0.88% Ni) is subjected to ultrasonic gas spraying at a pressure of 25 MPa and an acoustic treatment level of 164 dB. The layer-by-layer joining of solid–liquid granules takes place at 25–35% liquid phase. No primary transition metal intermetallics are observed in the structure of the compacted material. This structure is homogeneous, the average grain size is 5–10 μm, and the dendritic parameter does not exceed 10 μm. Therefore, a traditional granulation technology can be replaced by ultrasonic gas spraying to solve certain problems, such as the production of thin-walled sheets of high-strength or high-temperature aluminum alloys. A colloidal solution with a ζ potential of –15.4 mV and an average nanoparticle size of 200 nm is fabricated during the action of ultrasound on elemental selenium granules in distilled water by an and-face waveguide at a frequency of 22.4 kHz and a power of 300 W. As a result, we fabricated biologically active selenium-containing substances without chemically synthesized substances for medicine and agriculture purposes.

GAUSSIAN FUZZY ANALYTIC HIERARCHY PROCESS FOR THE EVALUATION OF BENEFIT, COST, AND RISK ANALYSIS IN THE INDONESIAN OIL AND GAS PROCESSING AREA

In the oil and gas processing area, adequate risk control should be prearranged to prevent serious accidents, such as major gas leak, fire, and explosion. Installing gas detectors at appropriate technology is one of indispensable conditions for an implementation of risk reduction measures. Open-path infrared and ultrasonic leak gas detector provide wide coverage of gas detection. This capability is advantageous to detect unintentionally gas release in wide coverage and windy-climate processing area. On the other hand, the installation and maintenance cost of those gas detectors are relatively high compared to point infrared and catalytic gas detector. Gaussian fuzzy analytic hierarchy process (Gaussian FAHP) is implemented to evaluate the selection of gas detector technology in terms of benefit, cost and risk criteria. Ten expert panelists from production, safety, and maintenance departments are involved in Delphi Technique to assess the sub-criteria of Gaussian FAHP. The Gaussian FAHP evaluation reveals that point infrared gas detector has the highest value among all gas detector technologies. This means that point infrared technology acquires efficient value in delivering service to process safety operation. The obtained result of consistency ratio is always below 0.1 (CR<0.1). By these terms, the Gaussian FAHP is consistent and applicable. By changing 50% amount of weight in all sub-criteria, there is no alternatives rank position change. The sensitivity analysis proves that the Gaussian FAHP evaluation in the research is consistent irrespectively of the sub-criteria change. The integration of Delphi Technique and Gaussian FAHP in the research is the scientific work to evaluate the best applied detector technology in the oil and gas processing area.

Empirical modeling and optimization of process parameters in ultrasonic assisted laser micromachining of Ti–6Al–4V

In the present study an attempt was made to create micro holes in Ti–6Al–4V titanium alloy by laser machining process. In order to enhance the machinability of the in terms of material removal rate (MRR) and recast layer thickness (RLT), ultrasonic vibration has been associated with the process. A comprehensive experimental study has been carried out to understand interaction effect of ultrasonic assisted laser machining parameters viz. ultrasonic vibration amplitude, laser power, pulse frequency and gas pressure on process quality characteristics. Analysis of variances has been carried out to find which factors has greatest effect on performance measures. Finally an optimization approach based on response surface method was carried out to obtain parameter setting regarding maximum MRR and minimum RLT and taper. Results indicated that the vibration amplitude has greatest effect on improving the MRR and RLT. Results revealed that selection of 40 μm vibration amplitude, 980 W laser power, 1200 Hz modulation frequency and 0.25 MPa gas pressure is an optimal parameter setting yields material removal rate of 2 mm3/min and RLT of 439 μm. The desirability for this parameter setting is 78%.

Experimental Study on the Effect of Gas Pressure on Ultrasonic Velocity and Anisotropy of Anthracite

To research the elasticity of gas-bearing coal fluid-solid two-phase medium with seismic exploration method is critical to the prevention of gas disasters. To investigate the elasticity, the ultrasonic elastic test of anthracite samples under different gas pressures was carried out and the ultrasonic velocity and anisotropy of the samples were analyzed in this study. The results show that the velocities (P- and S-waves) decrease in turn in the strike, dip, and vertical directions. However, a negative linear correlation is proved to exist between ultrasonic velocity and gas pressure. With the increase of gas pressure, the anisotropy degree of both the P-wave and the S-wave of the samples decreases but the declining degree of the P-wave is greater than that of the S-wave. In addition, the decrease in velocity and the anisotropy degree of the P-wave is greater than that of the S-wave, indicating that the P-wave is more sensitive to gas pressure changes in terms of velocity and its anisotropy degree.

Microstructure and mechanical properties of Q235 steel welded joint in pulsed and un-pulsed ultrasonic assisted gas tungsten arc welding

Pulsed ultrasonic assisted gas tungsten arc welding (PU-GTAW) is a newly developed welding method. In this work, the PU-GTAW and un-pulsed ultrasonic assisted gas tungsten arc welding (U-GTAW) was comparative investigated by analyzing the microstructure and mechanical properties of Q235 welded joints. The results showed that the improvement of PU-GTAW on microstructure was more efficient than that of the U-GTAW. The weld seam grain size in the U-TIG and PU-GTAW was refined compared with that of the conventional GTAW. Compared with the conventional GTAW, the change of texture type and the decrease of texture intensity were obtained in the U-TIG and PU-GTAW. The sizes of microstructures in the U-GTAW and PU-GTAW were reduced compared with that of the GTAW, which was caused by the refinement grain. Influence degree of the U-GTAW and PU-GTAW on the hardness of the weld seam was the same. The hardness was increased by about 30HV compared with that of the conventional GTAW.

A New Ultrasonic Gas Meter for Household Application

This paper proposes a new ultrasonic gas meter based on the time difference method. The gas flow measurement model is derived to reduce the environmental impact. A fluid pipeline structure is designed to reduce the impact of the flow field on the measurement. The max35104 time measurement chip is selected and the corresponding transmit and receive circuits are designed. Finally, the ultrasonic gas meter is tested in a standard device. The experimental results show that the designed household ultrasonic gas meter has an accuracy rating of 1.5 level.

Ultrasonic Gas Sensing by Two-Dimensional Surface Phononic Crystal Ring Resonators.

An acoustic ring resonator employing a two-dimensional surface phononic crystal is proposed for high-sensitivity detection in binary gas mixtures. Band analyses and frequency-domain simulations via the finite-element method reveal that a single band for spoof surface acoustic waves appears at ultrasonic frequencies around 58 kHz where modification of its dispersion due to varying gas composition results in a linear shift of the resonance frequency. The shift rate is -17.3 and 8.8 mHz/ppm for CO2 and CH4, respectively. The linear shift of resonance frequency is experimentally validated. In addition, the ring resonator can also be employed to track acoustic intensity variation with gas concentration, where exponentially decaying intensity for low concentrations leverages high-sensitivity operation.

The use of modern highly precise ultrasonic gas flowmeters and etalon stands to enlarge industrial resource efficiency

In this article we have described our new development that is the ultrasonic flowmeter with high dynamic range of 1 to 2000 for industrial applications. Its high accuracy of measurement can help gas consuming enterprises to save resources. Its software and the software of corresponding computing device is able to avoid gas leakage, to minimize energy consumption and to save human resources while maintaining metrological data. Shown are the new anti-adhesion technologies that can help to increase measurement accuracy and enlarge interval between counters verifications. Described is the low power consumption that makes it possible to use this ultrasonic flowmeter in hard remote environment without direct management for a period of several months. Experiments held in Turkmenistan have shown that device indications didn’t drift and remained stable during the year that is a great advantage in comparison to rotary and turbine flowmeters. Also described is the mobile ultrasonic calibration stand that uses the same physical principles and similar software. Outlined is the usage of modern wireless technologies to collect and transmit metrological data.

CALIBRATION OF ULTRASONIC FLOWMETER FOR WI-FI NETWORK WITH THE HELP OF WEB BROWSER

Objectives. The purpose of the work was to change the method of signal transmission containing metrological information from industrial time-pulse ultrasonic gas flow meter to a compu-ting device (CD). It was planned to expand the range of devices serving as gas flow calculators. A hardware-software complex (HSC) for automatic calibration / verification of ultrasonic flowmeters was to be developed. This HSC should work equally well on different operating systems. The information exchange between the CD and the flowmeter was to be carried out wirelessly.Method. The Wi-Fi Pro-tocol was used as a wireless Protocol. The energy-efficient ESP8266 controller was chosen as micro-controller to provide the functionality of Wi-Fi. The ESP8266 board acted as a Wi-Fi access point on the network to which CD was connected for data exchange. The ESP8266 microcontroller also served as a HTTP server. Exchange of metrological and other information was carried out by GET-requests. Given the need for continuous flow measurements and simultaneous communication between the user and the flow meter, requests to the server were transmitted using AJAX technology. The software part of the APK consisted of 3 programs: a program that measured the flow and transmitted the information further to the ESP8266 microcontroller, a server program recorded in ESP8266, providing a response to the requests of CD users, and the client program installed on the CD. The article discusses the key points of the HSC.Result. As a result of this work, the HSC was processed for calibration/verification of ultrasonic gas flow meters. For the first time this process for industrial flow meters was implemented using the ESP8266Wi-Fi controller as an access point. As a WU, it became possible to use any desktop or laptop computer or mobile device with a modern browser.Conclusion. The method proposed in the paper significantly simplified the data exchange between the VU and the flowmeter, reduced the cost of software development due to the common approach for different operating systems.

Analysis of droplet transfer, weld formation and microstructure in Al-Cu alloy bead welding joint with pulsed ultrasonic-GMAW method

The ultrasonic intensity was changed in different ultrasonic radiator heights (URH). Compared with conventional GMAW, the pulsed ultrasonic assisted gas metal arc welding (PU-GMAW) was an effective and newly-developed aluminum alloy welding method, because of its rapid droplet transfer and deep weld penetration. In PU-GMAW, the penetration and width of weld was increased due to the increase of the arc energy. When the URH was 20 mm and 22 mm, the droplet transfer mode of projected transfer changed to the mixed transition, which included projected transfer and short-circuiting transfer. The hardness of welded joint increased with the effect of pulsed ultrasonic, and the columnar crystal zone width of weld seam decreased. Ultrasonic radiation force was a determinant factor in arc compression and droplet transfer acceleration. The microstructure improvement in the PU-GMAW was caused by ultrasonic vibration and ultrasonic cavitation.

Manipulate Micrometer Surface and Nanometer Bulk Phase Separation Structures in the Active Layer of Organic Solar Cells via Synergy of Ultrasonic and High-Pressure Gas Spraying.

For organic solar cells, the vertical and lateral micro-/nanometer-scale structure in the active layer largely determines the device performance. In this work, the surface and bulk domain size of the photoactive layer are successfully manipulated with a facile two-step spraying method, that is, an ultrathin active layer by high-pressure spraying is deliberately stacked on top of the thick active layer by ultrasonic spraying. Thus, the morphology is effectively optimized with the comprehensive study of optical and electrical characteristics, such as photon absorption, exciton dissociation efficiency, and bimolecular recombination. Moreover, the novel method can be used not only in the fullerene system but also in the nonfullerene system, demonstrating the remarkable universality through this synergy method. This work provides an easy and reliable strategy to improve photovoltaic device performance in the industrial large-area spray-coating process.

Gas sensing through evanescent coupling of spoof surface acoustic waves

An ultrasonic gas sensor based on evanescent coupling of spoof surface acoustic waves between two surface phononic crystals containing trapezoidal grooves on rigid slabs is theoretically and experimentally demonstrated. Sensing properties for carbon dioxide in dry air at 25 °C and 760 Torr are investigated as an example. Band structure analyses reveal two spoof surface acoustic wave bands with opposite parities when the separation of surface phononic crystals is 1.5 times the periodicity of grooves. The beat length varies with frequency and carbon dioxide volume fraction, where the increase of the latter results in red shift of a sharp intense output peak at 59.69 kHz at a rate of 17.70 mHz/ppm and 16.20 mHz/ppm for carbon dioxide volume fractions up to 10,000 ppm, as measured through Finite-Element Method simulations and experiments, respectively. Gas sensing can also be achieved by measuring the output acoustic intensity at constant frequency, which exhibits a steep decrease with carbon dioxide volume fraction up to 2000 ppm.

Separation characteristics of hydrophilic ionic liquids from ionic liquids-water solution by ultrasonic atomization

Ionic liquids (ILs) have attracted much attention as promising alternatives for volatile organic solvents. Although the applications of ILs have been found in a diverse range of fields, there are a limited number of methods for the recovery of ILs so far. As an efficient separation method, therefore, ultrasonic atomization has been attempted to recover hydrophilic ILs, [Bmim][BF4], from ILs-water solution. In order to examine the separation characteristics of hydrophilic ILs-water solution, ultrasonic atomization of hydrophilic ILs-water solution was performed under various operating conditions such as initial ILs concentration, ultrasonic electric power, carrier gas flow rate, and operating temperature. The result showed that hydrophilic ILs recovery yield increased with a decrease in ultrasonic electric power, gas velocity, and temperature. As an increase in initial ILs concentration, however, higher ILs recovery yield was obtained. After 6 h of ultrasonic atomization of 50% (v/v) [Bmim][BF4]-water solution, 93.4% of initial ILs amount was recovered without any changes in their structure at ultrasonic power of 10 W, carrier gas flow of 5 L/min and temperature of 20 °C. It demonstrated that ultrasonic atomization could be used for the recovery of ILs from ILs-aqueous solution.

Design, simulation, fabrication and testing of ultrasonic gas flowmeter transducer (sensor)

PurposeInvasive transit-time ultrasonic flow measurement involves the use of ultrasonic transducers, which sense the flowing fluid and are the most important parts of an ultrasonic flowmeter. In this study, two ultrasonic transducers were designed, numerically simulated and fabricated to be used in an ultrasonic gas flowmeter.Design/methodology/approachPZT-5H piezoceramic elements with specific dimensions were designed and used as beating heart inside the transducers. Different methods, including impedance-frequency analysis, optical emission spectroscopy and performance tests in pressurized chambers were used to evaluate the piezoelectric elements, ultrasonic transducer housings and the fabricated transducers, respectively. In addition, finite element method results showed its ability for design stages of ultrasonic transducer.FindingsExperimental results for transit time difference (TTD) and the normalized received voltage were compared with simulation results at the same conditions. There was a quite good agreement between the two method results. Extensive simulation results showed that under the considered range of environmental conditions, the change of acoustic path length has the most impact on TTD, with respect to temperature and pressure. A change of 1 mm in acoustic path length leads to 0.74 per cent change in TTD, approximately. In addition, for normalized received voltage, 1 bar change in pressure has the most impact and its value is as high as 3.76 per cent.Practical implicationsThis method is possibly used in ultrasonic gas flowmeter fabrication.Originality/valueIn this work, design, fabrication, experimental tests and numerical simulation of ultrasonic transducers are presented.

Echo signal envelope fitting based signal processing methods for ultrasonic gas flow-meter

The echo signal of the ultrasonic gas flow-meter is difficult to locate, and the computation of signal processing methods proposed by others is extensive which affects the meter’s real-time performance. Aiming at solving these problems the echo signal envelopes under different flow rates are analyzed. And three kinds of signal processing methods based on echo signal envelope fitting are proposed. The shape of the echo signal remains the “approximate spindle shape” as the flow rate increases, and the envelope gradient of the middle parts of the upper envelope’s rising section and the lower envelope’s falling section remains the same at different flow rates, so the mathematical models of the two sections are established to obtain the envelope gradient curves of the two sections. With the envelope gradient curves, the ranges of envelope and peak points that linearly distributed are obtained. The least squares fitting is performed on those peak points to obtain two feature straight lines for respectively representing the upper envelope’s rising section and the lower envelope’s falling section. According to the spatial characteristics of the feature straight lines, the points on the feature straight lines are selected as the feature points for quickly locating the echo signal. According to the offline verification and comparison, the best one of three kinds of signal processing methods is selected, and realized on the hardware system of the two-channel ultrasonic gas flow-meter. The transmitter of two-channel ultrasonic gas flow-meter is developed based on FPGA & DSP dual core structure. It utilizes the parallel processing capacity and logic control ability of FPGA to realize the controlling of the high-speed ADC & DAC and the storage of the data. At the same time, it adopts the high-speed computing capacity of DSP to implement the digital signal processing method. The gas flow calibration experiments were carried out in a national accredited testing agency to verify the effectiveness of the signal processing methods and system. The experimental results show that the improved signal processing method based on echo signal upper and lower envelope fitting can quickly and accurately locate the echo signal. And the measurable range of the ultrasonic gas flow meter based on this signal processing method is broadened to 10 m3/h to 1,300 m3/h, and the turndown ratio is broadened to 1:130.

Numerical simulation on the generation of ultrasound and formation of water fog in the ultrasonic gas atomizer

The water spraying itself is a dynamic course, and it is affected not only by structural style of ultrasonic gas atomizer and compressed air pressure, but also by movement of compressed air flow and so on in the atomizer. Here, the main principle of fine droplet formation in the ultrasonic gas atomizer is that the liquid sheet is disrupted into droplets by the energy of the high velocity air. If the ultrasonic energy is supplied, finer droplets with high sphericity and uniform size distribution can be achieved.But it is difficult to measure the droplet sizes. An ingenious method of droplet measurement was attempted by capturing the droplets on a filter paper and there are subjected to image analysis to obtain the droplet sizes. However, droplet measurement is complicated and the correctness of the droplet sizes is not high. Also advantage of all of the device newly designed is not defined until the experimental measurement are advanced after they are manufactured. As development of an interpretative program, droplet measurement through the numerical simulation was attempted.This paper deals with the water atomization of ultrasonic gas atomizer by numerical simulation with CFD software-ANSYS Fluent. In this paper, generation of ultrasound is decided in the ultrasonic gas atomizer with resonance chamber and ultrasound characters (frequency, pressure level, power level) are decided. These results are proved through the comparison with experiment.The results indicate that ultrasonic gas atomizer is effective to apply to the industrial field such as dust cleaning process. Rational structure parameter and operating parameter are studied in next issue.

Modelling of received ultrasonic signals based on variable frequency analysis

Modelling of received ultrasonic signals can provide basis for both signal analysis and process in various instrumentations based on ultrasonic measurement. At present, some empirical models where the resonance frequencies set to fixed values have been proposed for this purpose. However, significant errors can be found between the existing models and actual ultrasonic signals. This paper proposes a modelling method of received ultrasonic signal based on variable frequency analysis, which is then validated by application on ultrasonic gas flowmeter. In this method, the traditional exponential model is modified to contain a time-varying frequency parameter, whose value can be estimated by analyzing the sampled signal using the Teager Energy Operator (TEO). Other parameters in the model can be further determined by parameter estimation algorithms. In order to meet TEO's application conditions, a sinusoidal transformation of the received signal using Hilbert transform before the time-varying frequency estimation is proposed. Wavelet packet de-noising method, lag parameter and smoothing spline are introduced to improve the performance of the time-varying frequency acquisition in the presence of noise. A number of numerical tests are conducted on simulated signals with different time-varying frequencies and noise to confirm the effectiveness of the proposed method. The actual application significance is validated by analysis of the actual received signals on ultrasonic gas flowmeter.

Gas Leak Location Detection Based on Data Fusion with Time Difference of Arrival and Energy Decay Using an Ultrasonic Sensor Array.

Ultrasonic gas leak location technology is based on the detection of ultrasonic waves generated by the ejection of pressured gas from leak holes in sealed containers or pipes. To obtain more accurate leak location information and determine the locations of leak holes in three-dimensional space, this paper proposes an ultrasonic leak location approach based on multi-algorithm data fusion. With the help of a planar ultrasonic sensor array, the eigenvectors of two individual algorithms, i.e., the arrival distance difference, as determined from the time difference of arrival (TDOA) location algorithm, and the ratio of arrival distances from the energy decay (ED) location algorithm, are extracted and fused to calculate the three-dimensional coordinates of leak holes. The fusion is based on an extended Kalman filter, in which the results of the individual algorithms are seen as observation values. The final system state matrix is composed of distances between the measured leak hole and the sensors. Our experiments show that, under the condition in which the pressure in the measured container is 100 kPa, and the leak hole–sensor distance is 800 mm, the maximum error of the calculated results based on the data fusion location algorithm is less than 20 mm, and the combined accuracy is better than those of the individual location algorithms.

A new discovery of arc shape in pulsed ultrasonic wave assisted TIG welding

An entirely new change-rule of an arc shape was found in the pulsed ultrasonic assisted tungsten-electrode inert gas welding process (PU-TIG), i.e., the arc shape had an obvious characteristic of periodic changes under the actions of a pulsed ultrasonic wave in PU-TIG. However, periodic changes of the arc shape were different between the arc white bright zone and the arc dark bright zone. The varying process of the arc shape was that the arc shape went through from expansion to contraction and re-expansion. Meanwhile, the constantly changing acoustic radiation force and electromagnetic force were the main cause of the periodic change of the arc shape in the PU-TIG welding process.