Pressure Temperature Distribution Research Articles

Study on the coupling model of wellbore temperature and pressure during the production of high temperature and high pressure gas well

During the production process of high temperature and high pressure gas well, high temperature fluids are produced from the formation. The change of wellbore temperature and pressure, due to the change of production, has an important impact on the production tubular column, which threatens the safety of the completion tubular column and the integrity of the wellbore. A single-phase gas transient flow temperature–pressure​ coupling mathematical model is developed for the fluid in the tubular column during gas well production, and the pressure and temperature distribution patterns of the gas in the tubular column during gas well production are obtained, and the influence of production rate on the temperature–pressure distribution in the tubular column during gas well production is analyzed. The coupled temperature–pressure model takes into account the mutual influence of temperature and pressure during the transient flow of gas in the column, and the comparison with the measured data in the field and the calculation results of the analytical model shows that the coupled model has higher accuracy. The model will provide theoretical support for the selection and optimal design of completion production tubular tools.

Coupled Modeling Approach for Laser Shock Peening of AA2198-T3: From Plasma and Shock Wave Simulation to Residual Stress Prediction

Laser shock peening (LSP) is a surface modification technique to improve the mechanical properties of metals and alloys, where physical phenomena are difficult to investigate, due to short time scales and extreme physical values. In this regard, simulations can significantly contribute to understand the underlying physics. In this paper, a coupled simulation approach for LSP is presented. A global model of laser–matter–plasma interaction is applied to determine the plasma pressure, which is used as surface loading in finite element (FE) simulations in order to predict residual stress (RS) profiles in the target material. The coupled model is applied to the LSP of AA2198-T3 with water confinement, 3×3mm2 square focus and 20 ns laser pulse duration. This investigation considers the variation in laser pulse energy (3 J and 5 J) and different protective coatings (none, aluminum and steel foil). A sensitivity analysis is conducted to evaluate the impact of parameter inaccuracies of the global model on the resulting RS. Adjustment of the global model to different laser pulse energies and coating materials allows us to compute the temporal pressure distributions to predict RS with FE simulations, which are in good agreement with the measurements.

FlowHaptics: Mid-Air Haptic Representation of Liquid Flow

Water is an essential substance for humans in their daily lives. There are many opportunities for us to come in contact with water, such as cooking, bathing, and swimming. However, few studies have reproduced the sensation of water touching the skin. This study aims to propose a novel midair haptic device, named FlowHaptics, that reproduces the feeling of the force of flowing water over human fingers using multiple air jets. We first estimated the temporal pressure distribution change of water in two-dimensional space using machine-learning-accelerated fluid simulation. We controlled the airflow based on the pressure distribution change obtained from the fluid simulation to reproduce the feeling of flowing water over the fingers using our proposed device, which can control multiple air jets in real time. We performed a psycho-physical evaluation of different flow velocities and a subjective evaluation of different velocity profiles. We found that FlowHaptics reliably created the illusion of the pressure distribution of flowing water on the fingers where the flow velocity could be distinguished within the range of 8.42% to 13.05%, and our estimated flow velocity profile with the configuration of three air jets felt more similar to flowing water when compared to a constant velocity profile according to the users.

Pump-probe X-ray holographic imaging of laser-induced cavitation bubbles with femtosecond FEL pulses

Cavitation bubbles can be seeded from a plasma following optical breakdown, by focusing an intense laser in water. The fast dynamics are associated with extreme states of gas and liquid, especially in the nascent state. This offers a unique setting to probe water and water vapor far-from equilibrium. However, current optical techniques cannot quantify these early states due to contrast and resolution limitations. X-ray holography with single X-ray free-electron laser pulses has now enabled a quasi-instantaneous high resolution structural probe with contrast proportional to the electron density of the object. In this work, we demonstrate cone-beam holographic flash imaging of laser-induced cavitation bubbles in water with nanofocused X-ray free-electron laser pulses. We quantify the spatial and temporal pressure distribution of the shockwave surrounding the expanding cavitation bubble at time delays shortly after seeding and compare the results to numerical simulations.

Near-field spatial and temporal blast pressure distributions from non-spherical charges: Horizontally-aligned cylinders

Research into the characterisation of blast loading on structures following the detonation of a high explosive commonly assumes that the charge is spherical. This has the advantage of simplifying experimental, analytical and computational studies. In practice, however, designers of protective structures must often consider explosive threats which have other geometric forms, which has significant influence on the loading imparted to structures very close to the explosion source. Hitherto, there has been little definitive experimental investigation of the ‘near-field’ blast load parameters from non-spherical explosive charges and studies that have been conducted are usually confined to measurement of the total impulse imparted to a target. Currently, a detailed understanding of the development of loading on a target, necessary to fully inform the design process and appraise the efficacy of predictions from computational models, is lacking. This article, the first part of a wider investigation into these geometrical effects, details work conducted to address this deficiency. Results are presented from an experimental study of loading from detonations of cylindrical charges, set with the longitudinal axis parallel to an effectively rigid target, instrumented to facilitate the capture of the spatial and temporal evolution of the loading at different radial and angular offsets from the charge. These results are compared against loads from spherical charges and the effect of charge shape is identified. Significant differences are observed in the mechanisms and magnitude of loading from cylindrical and spherical charges, which is confirmed through the use of numerical analysis. The overall study provides insights which will assist the future design of effective protection systems.

The influence of freestream turbulence on the temporal pressure distribution and lift of an airfoil

To gain insight on how freestream turbulence (FST) affects the aerodynamics of an airfoil in a systematic manner, the present study investigates a NREL S826 airfoil subjected to seven different incoming flows with varying degrees of FST. The Reynolds number was held at Rec ​= ​4.0 ​× ​105, while the turbulence intensity (Ti) was varied between 0.4% and 5.4%. An increase in Ti increases the maximum lift while having negligible effects on the stall angle. The lift slope in the linear region also generally increased with higher Ti. The latter observation contrasts with some earlier studies, and incoming flow homogeneity is a potential contributing factor to the differences seen here. Periodic pressure fluctuations are seen in the computed lift time-series signal when Ti is between 1% and 2% and the airfoil is operating in the linear region. These fluctuations arise from surface pressure oscillations that are likely excited by the relatively low incoming Ti. The overall effect is a reduction in the time-averaged lift under these operating conditions. At higher Ti, more energetic boundary layers develop over the airfoil’s suction side and the effect of these periodic pressure fluctuations is suppressed, leading to an increase in the produced lift.

Biomechanical monitoring and machine learning for the detection of lying postures

BackgroundPressure mapping technology has been adapted to monitor over prolonged periods to evaluate pressure ulcer risk in individuals during extended lying postures. However, temporal pressure distribution signals are not currently used to identify posture or mobility. The present study was designed to examine the potential of an automated approach for the detection of a range of static lying postures and corresponding transitions between postures. MethodsHealthy subjects (n = 19) adopted a range of sagittal and lateral lying postures. Parameters reflecting both the interactions at the support surface and body movements were continuously monitored. Subsequently, the derivative of each signal was examined to identify transitions between postures. Three machine learning algorithms, namely Naïve-Bayes, k-Nearest Neighbors and Support Vector Machine classifiers, were assessed to predict a range of static postures, established with a training model (n = 9) and validated with new input from test data (n = 10). FindingsResults showed that the derivative signals provided a means to detect transitions between postures, with actimetry providing the most distinct signal perturbations. The accuracy in predicting the range of postures from new test data ranged between 82%–100%, 70%–98% and 69%–100% for Naïve-Bayes, k-Nearest Neighbors and Support Vector Machine classifiers, respectively. InterpretationThe present study demonstrated that detection of both static postures and their corresponding transitions was achieved by combining machine learning algorithms with robust parameters from two monitoring systems. This approach has the potential to provide reliable indicators of posture and mobility, to support personalised pressure ulcer prevention strategies.

Experimental and numerical study on hydrodynamic impact of a disk in pure and aerated water

The hydrodynamic loads of a disk impacting pure and aerated water are investigated experimentally and numerically. Experiments are performed on a rigid disk with different aeration levels and focus on the spatial and temporal pressure distribution. Drop tests are conducted by a specially designed apparatus to prevent the variation of velocity during the slamming period. A specially designed bubble generator, able to adjust the void fraction, is utilized to generate uniform and tiny bubbles. A high-speed camera is utilized to record the water spray and splash curtain. A homemade compressible multiphase solver based on the reduced five equation model is adopted to evaluate the impact loads, which assumes the water and bubbles sharing the same velocity and pressure. The results show that bubbles in the water have a significant influence on the impact loads. As the void fraction increases from zero to nearly 1%, the peak impact pressure is reduced considerably and the impact duration is becoming obviously longer. In aerated water impact, the disk has a more uniform pressure distribution on the surface. However, the pressure impulse in aerated impact tests is basically unchanged compared with that in pure water.

Analysis of the influence of ultrahigh pressure on wellbore Fluid properties——Take Well ST1 in north Sichuan as an example

According to the research on wellbore pressure temperature prediction of ultra-high pressure gas Wells, the influence of ultra-high pressure on wellbore fluid physical property parameters cannot be ignored, the component model is adopted to calculate wellbore fluid PVT physical property, and the multi-phase flow model is modified to accurately predict wellbore pressure temperature distribution. For the prediction of gas deviation factor of well flow and gas viscosity of well flow, the component model has a high precision. By comparing with the prediction results of 8 black oil model methods, the pressure has a great influence on the black oil model. When the pressure is equal to 100MPa, the deviation value between the predicted results of Gopal method and Dranchuk-Abu-Kassem method and the component model is greater than 0.1, which can no longer guarantee the accuracy of gas deviation factor and gas viscosity prediction. Therefore, it is recommended to use the component model to predict the deviation factor and gas viscosity of gas well flow.

Aerodynamic Loading Induced by Muzzle Flows on Small Caliber Spin Stabilized Projectiles

Abstract In this study, we examined the aerodynamic loading on a small caliber rifle (spin stabilized) projectile moving in a muzzle flow field using an element method to analyze the loading and the effect of the angle of attack (for small angles from 0 to 3 deg) on the different components. The temporal pressure distribution on the projectile, which forms the basis of the element method, was computed using a computational fluid dynamics (CFD) analysis combined with a classical interior ballistics model. Then, a high-speed optical experiment was conducted to verify the results of the CFD method and ensure the accuracy of the calculations. The results were as follows: (a) similar to a large caliber projectile, the total axial force, which consisted primarily of the axial forces on the base and boattail, was found to have an inverse exponential relationship with time; (b) the overall lift was a combination of the lift of the base, boattail, cylinder, and nose; and (c) the interaction between the pitch moment of the base and that of the boattail was found to be the primary contributing factor to the total pitch moment. Based on these results, we recommend that the characteristics of the base and boattail be considered when specifying the geometric configuration of a projectile.

Temporal and spatial pressure distribution characteristics of hemispherical shell structure subjected to external explosion

It is necessary to master the propagation and distribution of the overpressure on a building under an explosive load before an anti-explosion design is achieved. However, there is very less available test data which can be applicable to multi-curved large-span space structure under a surface burst. In this work, a series of tests were performed to study the wave diffraction behaviour of a hemispherical structure by changing the nearest distance between the charge and structure and TNT equivalent. The purpose of the experiment was to develop an experimental dataset which could evaluate the accuracy and efficiency of the numerical model. A simplified method to study the blast load distribution on the hemispherical structure was proposed by numerical and geometric analysis. The numerical results showed that the peak overpressure, impulse, blast wave front arrival time, and positive phase duration were highly dependent on the span–distance ratio and span–charge ratio, which affect the significance of the reflecting and shielding effects. For a convenient engineering application, a series of pseudo-analytical formulas were suggested to estimate the pressure–time histories for an ideal hemisphere structure.

Experimental and numerical study of the tidal bore impact on a newly-developed sheet-pile groin in Qiantang river

An experimental study of the tidal bore impact on an innovatively-developed Sheet-Pile Groin (SPG) was conducted in a circulating flume. The water levels, tidal bore propagation velocity, temporal and spatial pressure distributions on a SPG were measured and analyzed. Then the pressure difference between the front and rear of the SPG piles was predicted and analyzed by FLOW 3D under various SPG perviousness ratio. The tidal bore height was a good index of the tidal bore strength and a good linear relationship was observed between the initial Froude number and the relative tidal bore height. The maximum rise of the water level at the SPG could reach 2.5 times the tidal bore height. The tidal bore pressure on the SPG can be reduced significantly by increasing the SPG perviousness ratio, especially when the tidal bore is high. The pressure difference between the front and rear of the pile distribute as an inverted trapezoid along the pile depth and can be significantly reduced with the increase of SPG perviousness ratio. These findings can provide guidelines for the design of the newly-developed SPG in tidal bore zone.

Customizable Pressure Sensor Array: Design and Evaluation

Pressure senor array is widely used in gait analysis and robotics. To meet the demand on different sizes and reduce the manufacture costs, in this paper, we proposed a design method for customizable pressure sensor array which could be trimmed into different sizes. The customizable pressure sensor array was made of piezo-resistive fabric and flexible circuits, which made it suitable for the sensor array to be trimmed into different sizes. Pressure sensors were uniformly distributed to maintain the resolution of the pressure sensor array when trimmed into different sizes. Wires on the flexible circuits were designed to ensure that all the full/partial sensors remained on the sensor array could be used after trimming the sensor array into a smaller size. To evaluate the design method, we designed insole shaped customizable pressure sensor arrays to analyze gait parameters such as gait cycle and cadence. Spatial and temporal pressure distribution patterns acquired with trimmed and non-trimmed sensor arrays were used for analyzing. Experiment results indicated that the customizable pressure sensor array designed with the method proposed in this paper could be used to acquire spatial and temporal pressure distribution patterns without being influenced by trimming.

Impact Pressure Distribution on a Monopile Structure Excited by Irregular Breaking Wave

Abstract The problem of impact pressure distribution on a monopole structure excited by irregular breaking waves is investigated. The analysis is performed by applying a numerical model that combines potential flow model with a Navier-Stokes/VOF solution. The temporal pressure distribution is analysed for two breaking wave cases characterized by the significant difference in the steepness of the wave front. The peak impact pressures are observed in the region below the overturning wave jet where the pressure increases rapidly resulting in a peak value of the slamming coefficient equal to Cs=2π. The vertical load distribution provided by the derived model is more realistic than a rectangular shape distribution applied in engineering practice. This is because the vertical load distribution strongly depends on breaking wave shape and it is difficult to uniquely approximate such a load distribution by a rectangle.

Development of a Full-Scale Structural Testing Program to Evaluate the Resistance of Australian Houses to Wind Loads

Extensive damage to houses during severe tropical cyclones in the 1970s in Australia highlighted the need for research-based structural engineering principles to be applied in design and construction of houses. Houses have structural redundancies and complex load paths, so the analysis of even simple houses was complicated. In order to evaluate the structural performance of these parallel systems, full-scale house testing commenced at the Cyclone Testing Station (CTS) in the early 1980s with the static multipoint loading of an old house destined for demolition. Following that test program, nine full-scale houses were tested under static and cyclic loading to evaluate load paths in different types of houses with different building practices and materials. Results have been incorporated into amendments of house construction codes, standards and manuals. Advances in computer modeling and instrumentation have led to more sophisticated full-scale studies. Data on real houses under construction has informed this work and enabled analytical models to incorporate variability in strength of connections in a way that a single test cannot. Progressive failure in the structural systems of timber-framed housing can now be studied to differentiate between houses that have significant damage and seemingly identical ones that have limited damage in the same wind event. These studies involve wind tunnel investigations to determine temporal pressure distributions; full-scale multiple tests on connections (with and without construction defects) to determine statistical distributions of strength and load/deflection relationships; and full-scale tests on houses or portions of houses to determine load sharing mechanisms between parallel structural and non-structural elements. The results of the test programs were used to calibrate the analytical models, which can be used for reliability studies. The paper presents a summary of the methodology and findings from previous CTS full-scale house tests. The results of the most recent research using full-scale tests on a portion of a house and its companion numerical models are discussed and the benefits and limitations of the process outlined.

Flexible pressure sensors for smart protective clothing against impact loading

The development of smart protective clothing will facilitate the quick detection of injuries from contact sports, traffic collisions and other accidents. To obtain real-time information like spatial and temporal pressure distributions on the clothing, flexible pressure sensor arrays are required. Based on a resistive fabric strain sensor we demonstrate all flexible, resistive pressure sensors with a large workable pressure range (0–8 MPa), a high sensitivity (1 MPa−1) and an excellent repeatability (lowest non-repeatability ±2.4% from 0.8 to 8 MPa) that can be inexpensively fabricated using fabric strain sensors and biocompatible polydimethylsiloxane (PDMS). The pressure sensitivity is tunable by using elastomers with different elasticities or by the pre-strain control of fabric strain sensors. Finite element simulation further confirms the sensor design. The simple structure, large workable pressure range, high sensitivity, high flexibility, facile fabrication and low cost of these pressure sensors make them promising candidates for smart protective clothing against impact loading.

Numerical Investigation of the Unsteady Interaction Within a Close-Coupled Centrifugal Compressor Used in an Aero Engine

Abstract The present work forms part of a research project of the Institute of Jet Propulsion and Turbomachinery at the RWTH Aachen University in collaboration with GE Aviation. The subject is the detailed numerical analysis of the unsteady flow field, focusing on the interaction between the impeller and the passage diffuser of a close-coupled transonic centrifugal compressor used in an aero engine. The centrifugal compressor investigated is characterized by a close-coupled impeller and passage diffuser with a radial gap of only 3.6%. The close coupling tends to provide a high aerodynamic efficiency but simultaneously cause a high unsteady interaction between the impeller and the diffuser. These unsteady effects can have a significant impact on the performance of both components and present a challenge to state-of-the-art numerical methods. With increasing compressor efficiency, the more important it is to have an understanding of the detailed unsteady flow physics. Experimental data was obtained from a state-of-the art centrifugal compressor test rig located at the Institute of Jet Propulsion. Steady and unsteady pressure measurements within the impeller and diffuser are used to gain detailed information on the temporal, time-averaged, and spectral pressure distributions within the stage to validate the CFD. The work presented here shows the unsteady phenomena caused by the interaction and the location and propagation of these phenomena within the centrifugal stage. Within the impeller, the exducer is in first order excited by the blade passing frequency (BPF) of the diffuser, whereas in the diffuser both the BPF and the passage passing frequency (PPF), are present up until the end of the pipe-diffuser. Significant effects on the integral component performance could only be identified for the impeller. Special focus is paid to evaluate the diffuser upstream pressure field, since this is the major source of unsteadiness within the impeller. The performance of the rotor decreases due to the unsteady interaction. This effect is traced back to the unsteady tip-clearance flow, in which the time-averaged mass transport decreases, whereas the specific entropy production increases in a nonlinear way. Within the diffuser, local effects counteracting with respect to the integral performance are found. In front of the throat, there is less decay in the total pressure as a result of tangentially expanding pressure waves. Within the passage a decrease in flow uniformity in the unsteady flow is identified as the reason for the lower diffusion up until the throat and higher losses within the downstream diffuser passage.

Considerations concerning the analysis of NPP structures subjected to blast loading

Basic features of the loads induced on structures by air blasts are described in IAEA Design Guide NS-G-1.5 (2003) in terms of a normalized distance that takes into account the amount and type of explosive charge. The guide presents charts that allow the determination of the peak value of the incident pressure, the total impulse of the positive phase and other relevant design parameters, which are generally used for design or verification purposes of sensitive nuclear structures. For the determination of the resulting actions on structures subjected to a specified blast event, the load-time functions induced by the incident pressure wave must next be evaluated, as discussed for example by Kinney and Graham. The authors note that a number of models are available for such purpose, such as Zaslavskii et al., which lead to different predictions and raise the issue of model uncertainty in this problem. In this paper, the uncertainties expected in the various stages of the process are examined in connection with the analysis of the air vent stack of a NPP presently under design. The spatial and temporal pressure distributions induced at the site by the blast were determined by means of a finite element model that simulates the shock wave propagation considering the topographical features of the site and the main structures of the NPP. The numerically determined pressures are compared with the IAEA design guide recommendations. Next, the loads induced in the air vent stack by the shock wave as well as the dynamic response of the stack are determined employing several models. The validity of commonly accepted assumptions in the determination of the response of structures to blast loading is finally discussed.

Experimental evaluation of slamming pressure models used in structural design of high-speed craft

In this paper a methodology that enables detailed studies of the momentary slamming pressure distribution and the related structural loads is presented. The methodology involves pressure measurements, spatial and temporal pressure distribution reconstruction, and finite element analysis. Using a set of model experiments with a high-speed planing craft towed in irregular waves, the methodology is applied to evaluate different slamming pressure models regarding their ability to accurately represent the structure loads. The slamming equivalent uniform pressure model used in the prevailing semi-empirical design methods, and non-uniform time-dependent pressure models used in a method for direct calculation, are considered. It is concluded that for smaller structure members, typically found in densely spaced metal structures, the uniform pressure model performs well with respect to accurately representing the structure loads. However, for larger members found in modern sandwich structures, the underestimation of structure loads is significant, especially with respect to the shear forces. The non-uniform pressure modeling technique is concluded to be promising regarding its ability to accurately represent the structure loads, regardless of structure member size. The presented methodology is concluded to be a useful tool in further research regarding the evaluation and development of methods for high-speed craft structural design.

Temporal and spatial pore water pressure distribution surrounding a vertical landfill leachate recirculation well.

Addition of liquids into landfilled waste can result in an increase in pore water pressure, and this in turn may increase concerns with respect to geotechnical stability of the landfilled waste mass. While the impact of vertical well leachate recirculation on landfill pore water pressures has been mathematically modeled, measurements of these systems in operating landfills have not been reported. Pressure readings from vibrating wire piezometers placed in the waste surrounding a liquids addition well at a full-scale operating landfill in Florida were recorded over a 2-year period. Prior to the addition of liquids, measured pore pressures were found to increase with landfill depth, an indication of gas pressure increase and decreasing waste permeability with depth. When liquid addition commenced, piezometers located closer to either the leachate injection well or the landfill surface responded more rapidly to leachate addition relative to those far from the well and those at deeper locations. After liquid addition stopped, measured pore pressures did not immediately drop, but slowly decreased with time. Despite the large pressures present at the bottom of the liquid addition well, much smaller pressures were measured in the surrounding waste. The spatial variation of the pressures recorded in this study suggests that waste permeability is anisotropic and decreases with depth.