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In recent years, passive wireless sensors have been studied for various infrastructure sectors, making them a research and development focus. While substantial evidence already supports their viability, further effort is needed to understand their dependability and applicability. As a result, issues related to the theory and implementation of wireless sensors still need to be resolved. This paper aims to review and summarize the progress of the different materials used in different passive sensors, the current status of the passive wireless sensor readout devices, and the latest peripheral devices. It will also cover other related aspects such as the system equipment of passive wireless sensors and the nanogenerators for the energy harvesting for self-powered sensors for applications in contemporary life scenarios. At the same time, the challenges for future developments and applications of passive wireless are discussed. [ABSTRACT FROM AUTHOR]

Fluid viscosity is one of the key factors affecting the cavitation characteristics of the Helico-axial Multiphase Pump (HAMP). In this paper, fluids with viscosities of 24.46 mm2/s, 48.48 mm2/s, 60.70 mm2/s, and 120.0 mm2/s were investigated by numerical simulation. The Ansys Fluent software was employed to conduct the simulation. The mixture multiphase flow model and the RNG k-ε turbulence model were adopted. The Singhal cavitation model was employed to consider the effects of the non-condensable gas on cavitation. An experiment was carried out to validate the numerical method. The results showed that the Net Positive Suction Head-available (NPSHA) of the pump decreased as the fluid viscosity increased. Under the critical NPSHA condition, the NPSHA decreased from 5.11 m to 3.68 m as the fluid viscosity increased from 24.46 mm2/s to 120.0 mm2/s. This suggested that the cavitation performance of the pump was deteriorated under high fluid viscosity. The impeller passage area occupied by the vapor increased when the fluid viscosity increased. Nearly half of the flow passages were occupied by cavitation bubbles when the fluid viscosity increased to 120.0 mm2/s. The vapor volume fraction, both on the suction surface and pressure surface of the blade, increased with the fluid viscosity. The vapor on the suction surface was mainly distributed in the region with the streamwise between 0 and 0.36 when the fluid viscosity was 24.46 mm2/s; while the high vapor volume fraction range increased to the streamwise of 0.42 when the fluid viscosity increased to 120.0 mm2/s. The higher vapor volume fraction corresponded with the lower pressure. It was also found that the turbulent kinetic energy, both on the suction surface and pressure surface, increased with the fluid viscosity, which was the favorite for producing more cavitation bubbles. Furthermore, the maximum velocity area was mainly concentrated in the inlet area of the impeller. The velocity distribution in the impeller was basically the same with the viscosity of 24.46 mm2/s and 48.48 mm2/s. When the viscosity further increased to 60.70 mm2/s, the maximum velocity area in the impeller was relatively large. This study provides a reference for designing the HAMP. [ABSTRACT FROM AUTHOR]

Highlights • A multi-wire capacitance probe measurement device was developed. • Water layer height and void fraction at different circumferential positions was measured. • Water layer height and its variations with time at different circumferential positions were analyzed. • Void fraction prediction correlations were compared and best performing correlation was recommended. Abstract The void fraction of stratified gas-liquid flow is crucial to determine mixture density, calculate pressure gradient, obtain phase flow rate, analyze flow structure and monitor flow processes. The measurement and prediction of void fraction is of particular interest in many industrial processes. The objective of this paper is to develop a new method to accurately measure the void fraction in the stratified gas-liquid flow. A measurement device named multi-wire capacitance probe which is based on the single-wire capacitance probe is developed. The device can obtain the average void fraction as well as the local void fraction by measuring the water layer height at different circumferential positions of the pipe. We analyze the water layer height and its variations with time at different circumferential positions under different superficial gas and liquid velocity. We also discuss the local void fraction at different circumferential position and the average void fraction of the circular cross section by measuring the water layer height. Comparisons of ten existing prediction correlations using the measured void fraction are made. The correlation of Armand–Massina is recommended to predict the void fraction of stratified gas-liquid flow. The relative error of the void fraction predicted by this correlation is within ±3.0% under the 95.65% confidence level. [ABSTRACT FROM AUTHOR]

Abstract To gain a deeper understanding of the performance of V-Cone meter in low pressure wet gas measurement, the over-reading of the V-Cone meter was experimentally investigated in the present study. The equivalent diameter ratio of the V-Cone meter is 0.55. The experimental fluids were air and tap water. The operating pressure and the gas volume fraction ranged from 0.1 MPa to 0.4 MPa and 97.52%–100%, respectively. The results showed that the existing V-Cone wet gas correlation, which was developed for the medium and high pressure wet gas cannot be well extended to the low pressure conditions. The Chisholm exponent monotonically decreased with the ratio of liquid-to-gas mass flow rate increasing, and was almost not affected by the gas to liquid density ratio and the gas densiometric Froude number in the present test ranges. A measurement correlation dedicated for the low pressure wet gas was developed. In the present cases, the relative deviation of the gas mass flow rate predicted by the new correlation was within ±4.0% and ±3.0% under the 95% and 90% confidence level, respectively; the average relative deviation was 0.046%. Our results provide insights into the measurement performance of V-Cone meter in low pressure wet gas and may help to develop a more comprehensive wet gas correlation. Graphical abstract Fitting curve between m l /m g and n. Image 1 Highlights • V-Cone meter over-reading in low pressure wet gas measurement was investigated. • Effects of parameters on Chisholm exponent were analyzed. • A measurement correlation in low pressure wet gas was developed. [ABSTRACT FROM AUTHOR]

Online measurement of gas and liquid flow rates in wet gas is of great significance in industry. When the differential pressure meter is used to measure the gas and liquid flow rates, an over-reading correlation is needed to correct the liquid-induced overestimation of the gas flow rate and an auxiliary correlation is needed to obtain the liquid fraction or flow rate. With the two correlations incorporated, the gas and liquid flow rates can be calculated. In the present study, error analysis of this metering method is conducted. The results demonstrate that metering methods based on differential pressure exhibit similar error pattern, i.e., the prediction error of gas phase is small while that of the liquid phase is large. This phenomenon can be interpreted by error propagation and the underlying physics is that the two-phase differential pressure is mainly dependent on the gas phase but insensitive to the liquid phase. It is found that both the mean value and the fluctuation of the differential pressure signals are able to reflect flow rate changes of wet gas flow. However, metering methods based on the differential pressure fluctuation present larger prediction errors than that based on the differential pressure mean value. The reason is that the differential pressure fluctuation has much poorer repeatability compared with the differential pressure mean value. [ABSTRACT FROM AUTHOR]

In the present study, an accurate cost-effective online system for metering both the gas flow rate and the liquid flow rate in wet gas with only one V-Cone throttle device is developed. The two-phase mass flow coefficient is employed to correct the measurement deviation of the V-Cone throttle device. The effects of the liquid densiometric Froude number, the gas densiometric Froude number and the ratio of gas density to liquid density on the two-phase mass flow coefficient are experimentally investigated. The equivalent diameter ratio of the V-Cone throttle device is 0.55. The experimental fluids are air and tap water. The operating pressure, the superficial gas velocity and superficial liquid velocity range from 0.1 MPa to 0.3 MPa, 4.87 m/s to 25.26 m/s and 0 to 0.38 m/s, respectively. The results show that the two-phase mass flow coefficient linearly increases with the liquid densiometric Froude number and is affected by the gas densiometric Froude number and the ratio of gas density to liquid density. On the basis of the two-phase mass flow coefficient, the correlation for measuring the gas flow rate of the wet gas is developed. To reflect the influences of the liquid on the measurement, the pressure loss ratio of the V-Cone throttle is proposed. By incorporating the gas measurement correlation of the wet gas, the wet gas correlations to simultaneously meter the gas and liquid flow rate are concluded. In the present cases, the relative error of the gas mass flow rate predicted by the correlations is within ±5.0% and the mean absolute percentage error is 2.52%; the full scale relative error of the liquid mass flow rate is within ±5.0% and the mean absolute percentage error is 7.03%. The method proposed in this study creates a simple inexpensive wet gas metering system that can operate well in a significant range of industrial applications. [ABSTRACT FROM AUTHOR]

Much attention has been devoted to the study of the correlation of the wet gas flow rate measurement with a Venturi meter. However, up to now a widely-accepted correlation or model is not available. In this study, a new correlation for wet gas flow rate measurement with Venturi meter based on a two-phase mass flow coefficient was proposed. The two-phase mass flow coefficient was found to linearly increase with the Lockhart–Martinelli parameter and decrease with the increase of the gas-to-liquid density ratio. It also decreased with the gas densiometric Froude number increasing. The relationships of the two-phase mass flow coefficient with the Lockhart–Martinelli parameter, the gas densiometric Froude number and the ratio of gas to liquid density were concluded. Comparisons with the existing correlations showed that the new correlation predicted the wet gas flow rate more accurately than other correlations under the following conditions: the Lockhart–Martinelli parameter ranging from 0 to 0.3, the gas densiometric Froude number from 0.6 to 4.7, the ratio of gas to liquid density from 0.01 to 0.081 and the inlet diameter of the Venturi meter from 50 to 200 mm. The present work provided an alternative approach to the study on the wet gas flow rate measurement with the Venturi meter. [ABSTRACT FROM AUTHOR]

Abstract: Study of the Venturi meter over-reading in wet gas is of considerable importance for the wet gas metering. Although the impacts of different parameters (e.g., liquid fraction, pressure and gas flow rate) on the over-reading have been widely investigated, the underlying mechanism on how these parameters act on the over-reading is still not fully understood. In this investigation, five types of turbulence models, including the standard - model, the RNG - model, the realizable - model, the standard - model and the Reynolds stress model were examined. It was found that the standard - model was in better agreement with the experimental data. From the simulations, how and why the over-reading produced was explained. Then the liquid phase distributions and its impact on the velocity field and the pressure profiles were discussed. The results indicated that the liquid accumulated in the convergent section of the Venturi tube, where an annular liquid jet was formed. The static pressure in the throat declined along the throat, which made the static pressure in the throat unstable. To reduce their adverse effects on the over-reading of the wet gas flow, it was suggested that the classical Venturi tube should extend the length of the throat and decrease the convergent angle. This study gained a more comprehensive understanding of Venturi meter wet gas over-reading and provided a reference for the design of a wet gas Venturi meter prototype. [Copyright &y& Elsevier]

Determining the characteristics of gas-liquid two-phase flow in centrifugal pumps is essential for a better understanding of pump performance. In this study, a visualization investigation was performed to determine the effect of the gas-liquid distribution in the impeller on the performance of a centrifugal pump with a closed impeller. Emphasis was placed on the influences of the inlet gas volume fraction (IGVF), flow rate, and rotational speed on the gas-liquid distribution in the impeller and, thus, on the surging characteristics of the pump. The correlation mechanism between the distribution of the gas-liquid phase in the impeller and the surging characteristics of the pump was revealed. Finally, several surging prediction models were examined. The results show that the gas-liquid two-phase distribution in the impeller has an immediate impact on the pressure increment and efficiency of the pump. The increase in IGVF directly induced pump surging by changing the flow pattern in the impeller. Surging occurred when the flow pattern changed from gas pocket flow to segregated flow. It was also found that pump surging could be eliminated by adjusting the flow rate and increasing the rotational speed, which changed the flow pattern inside the impeller. Compared with the experimental results, the critical IGVF obtained by the existing surging prediction model exhibits some deviation. The surging prediction model dedicated to the volute centrifugal pump requires further investigation. The results reported here can provide better insight into the performance of volute-type centrifugal pumps and provide a reference for developing corresponding surging prediction models. [Display omitted] • Flow pattern in pump impeller under bubble inflow was obtained. • Influence of parameters on gas-liquid distribution in impeller was investigated. • Relationship between gas-liquid distribution in impeller and pump performance was analyzed. • Several surging models for predicting critical inlet gas volume fraction were examined. [ABSTRACT FROM AUTHOR]

The gas and liquid distributions in the pump are significant for understanding the pump performance under bubble flow inlet. An accurate numerical simulation method will contribute to obtain the gas and liquid distribution characteristics in the pump. In this study, the simulation method based on the CFD-PBM (CFD-Population Balance Model) coupling model was developed and validated by experiments. The simulation results predicted by the new numerical method agreed better with the experimental results than calculations based on Eulerian-Eulerian model. The coalescence and breakup of bubbles in the centrifugal pump should be considered, which is well handled by the CFD-PBM coupling model. The influences of inlet gas volume fraction and liquid phase flow rate on the void fraction and bubble size distribution in the centrifugal pump were investigated. The results show that more bubbles accumulated in the impeller than in the volute as inlet gas volume fraction increased to a certain value. Small gas pockets accumulated in the impeller and formed large gas masses around the impeller inlet leading to "Surging" of the pump. The percentages of bubbles with large diameter increased with the inlet gas volume fraction increasing, rather, the bubbles with small diameter decreased. In addition, the bubbles were more likely to break up into smaller bubbles and difficult to aggregate into bigger bubbles when the liquid flow rate increased. Several void fraction and bubble size prediction models were also compared for the present cases. This study provides an effective method to simulate the pump characteristics under gas and liquid conditions, which is helpful to investigate the gas-liquid performance of the pump. Image 1 • A numerical simulation method based on CFD-PBM model was developed. • Void fraction in centrifugal pump was investigated. • Bubble size distribution in centrifugal pump was investigated. • Several void fraction and bubble-size prediction models were analyzed. [ABSTRACT FROM AUTHOR]

This study investigates the measurement performance of a cone meter using bionic drag reduction methods. Three types of bionic non-smooth cone structures are designed and their impact on the pressure loss coefficient (ζ) and discharge coefficient (C d) is analyzed. The results demonstrate that the bionic structures on the cone surface have a significant effect on ζ and C d. Among the three structures, the riblet structure on the cone surface increases ζ and decreases C d , which greatly enhances measurement performance. For Reynolds numbers of 1.0 × 105 or higher, the cone meter with riblet-3 structure reduces ζ by 26.7 % and increases C d by 15.3 %. The measurement accuracy of the cone meter with riblet-3 structure improves to ±1.5 %. The presence of reverse vortices between the ridges of the riblet-structured cone acts as "bearings", converting sliding friction into rolling friction and achieving pressure loss reduction. [Display omitted] • Improved measurement performance of cone meter using bionic drag reduction. • Design and analysis of three bionic non-smooth cone structures. • Riblet structure was most effective in enhancing measurement accuracy. • Mechanism of pressure loss reduction of bionic cone meter was revealed. [ABSTRACT FROM AUTHOR]

• The mutual information method was used as a feature selection method for choosing geological and hydraulic fracturing features. • The Gaussian process regression (GPR) method was applied to predict the open hole flow rate after fracturing work. • The performances of the GPR, random forest, and ANN models were compared based on the actual engineering data of 175 sample wells. • The Shapley additive explanation value method was applied to obtain the dominant factors influencing the initial gas production rate. In shale gas production rate prediction, data are commonly acquired through simulations, which offer benefits but cannot fully predict the outcome of real engineering projects. This paper applied a Gaussian process regression (GPR) model, which was trained on the geological and field data from 175 wells in the Fuling gas field, China. GPR was chosen because this method can be suitably applied to a small dataset. To improve the accuracy, reduce the computational consumption, and increase the interpretability of the model, the mutual information method was used for feature selection after Pearson coefficient analysis. Based on comparison of the GPR, random forest and artificial neural network models, GPR achieved the best performance with the mutual information feature selection method, exhibiting R2 values of 0.71 and 0.68 for the training and test datasets, respectively. After model training, the model applied the Shapley additive explanation (SHAP) value method. The results indicate that geological factors dominate the gas production rate in Fuling, China. The volume of fluid loss could exert a negative impact on production rates and increase the consumption of 40–70 mesh proppant could increase gas production in Fuling. [ABSTRACT FROM AUTHOR]

This work experimentally studied the influence of gas and liquid distribution on a semi-open mixed-flow pump performance. High speed photography technology was contributed to obtain the evolution law of bubbles in the impeller. The results show that the inlet gas volume fraction (IGVF) and liquid flow rate are the main factors affecting the performance of the pump. The pressurization capacity linearly decreases with the increase in IGVF when the liquid flow rate is close the best efficiency point. However, this factor suddenly drops when the IGVF reaches a certain critical value under the condition of a low liquid flow rate. The spatiotemporal evolution characteristics of the isolated bubbles and gas column in the segregated flow were investigated. In addition, the bubbles are evenly distributed, and the flow pattern is mainly bubbly flow (BF) or aggregated BF (ABF) in the impeller inlet area without blades. Under small liquid flow rate conditions, the bubbles tend to coalesce into larger-sized gas-pocket with an increase in IGVF. The tip leakage vortex increases the turbulence intensity of the flow field. The results show that the bubbles downstream of the tip leakage vortex in the impeller channels are more easily broken into smaller bubbles and form a BF or ABF. • The visualization experiment of mixed-flow gas-liquid two-phase pump is carried out. • Relationship between external characteristics and bubble distribution is clarified. • Gas-liquid two-phase flow patterns in the impeller of the mixed-flow pump are obtained. • The evolution process of isolated bubbles passing through the tip clearance is found. • The dynamic circulation process of air pocket in the impeller are clarified. [ABSTRACT FROM AUTHOR]

To develop a reliable wet gas flowrate measurement model, the relationships between pressure drop characteristics and entrainment downstream of the cone are investigated experimentally. The equivalent diameter ratio of the cone is 0.45. The experimental fluids are air and tap water with X LM in the range of 0–0.3. The two-phase mass flow coefficient and pressure loss ratio are employed to establish the measurement model. The piecewise characteristics of pressure loss ratio are disclosed innovatively, which is explained by the different intensity of entrainment downstream of cone caused by gas-liquid jetting. A simplified method for evaluating the degree of entrainment is proposed to facilitate the establishment of the modified measurement model. Under the present experimental conditions, the relative error of liquid fluctuates within ±20% when X LM is larger than 0.02, and the relative error of gas flowrate is within ±5%. Compared with the model without piecewise consideration, the relative error of the liquid flowrate of the modified model reduces obviously under low wetness conditions (0.02< X LM <0.1). The modified measurement model provides a reliable and cost-effective technology for wet gas flowrate measurement. • The piecewise characteristics of the pressure loss ratio are disclosed and analyzed based on visualization. • The liquid layer thickness upstream of the cone is calculated to facilitate establishing the modified model. • The modified model improves the prediction accuracy under low wetness conditions. [ABSTRACT FROM AUTHOR]

The online measurement of wet gas with extremely-low liquid loading (Lockhart-Martinelli parameter lower than 0.02) remains a challenge. In this study, three types of throttle devices, Venturi, orifice plate and cone, are compared experimentally with air-water two-phase flow in a horizontal pipe of inner diameter of 50 mm. High-precision correlations are established to measure the gas and liquid flowrates via a single throttle device. Results show that the two-phase mass flow coefficient (K) of the three throttle devices all increase linearly with the liquid densiometric Froude number and the K correlations are established respectively to correct the gas mass flowrate deviation. The pressure loss ratio (δ) for Venturi is sensitive and monotonous to the liquid loading, which contributes to the high accuracy of liquid flowrate measurement. By incorporating the K correlations, both the gas and liquid mass flowrates can be predicted precisely. The relative error of the gas mass flowrate predicted by the Venturi is within ±2.0% at 95% confidence level, and that of the liquid mass flowrate is within ±15% at 90% confidence level. • Performance of three throttle devices for wet gas with extremely-low liquid loading are investigated. • The two-phase flow coefficient and the pressure loss ratio are analyzed. • The new gas and liquid mass flowrates measurement correlations are established. • The Venturi shows high prediction accuracy on two phase flowrates measurement. [ABSTRACT FROM AUTHOR]

• A high-accuracy method for measuring flow rates in wet gas is proposed. • It is based on the combination of the cone throttle device and the neural networks. • PDF and PSD are applied to the differential pressure fluctuation of the cone. • PCA are used to extract independent features to the neural networks. The online measurement of gas and liquid flow rates in wet gas is of great significance. This paper presents a new method to measure gas and liquid flow rates of wet gas by combining the cone throttle device and machine learning techniques. The equivalent diameter ratio of the cone device is 0.45. Experiments are carried out in a horizontal pipe of diameter 50 mm and the operating pressure ranges from 100 kPa to 250 kPa. The working fluids are the mixture of air and water with the Lockhart-Martinelli parameter (X LM) less than 0.3. The multilayer feedforward neural network is used for developing the measurement model. The model requires representative features as inputs and uses the gas and liquid flow rates as outputs. In addition to the mean values of the permanent pressure loss and the upstream-throat differential pressure, the probability density function (PDF) and power spectral density (PSD) of the upstream-throat differential pressure fluctuation are also extracted as representative features. With the principal component analysis method, the independent PDF and PSD features are obtained. The untrained dataset is used to evaluate the performance of the neural network model. Predictions of the flow rates are in good agreement with the experiments. The mean relative errors of the gas and liquid flow rates are 0.05% and −3.66%, respectively. The results show that the proposed method is capable of establishing the implicit correlations between the characteristic parameters of wet gas and the corresponding flow rates. [ABSTRACT FROM AUTHOR]