Internal Pressure Changes Research Articles

Indirect assessment of the rolling resistance of a car tire in the starting mode of motion

Problem. From the condition of the tires and their correct choice depending on the weather conditions, first of all, the indicators of many operational properties of the car depend. The internal pressure and temperature of the tire increases during driving, as a result, there is a significant effect on the rolling resistance of the tire. At high values of the rolling resistance coefficient, first of all, fuel consumption increases, tire wear increases, etc. It is important to know how the rolling resistance coefficient changes during the starting period of motion. Goal. The purpose of this work is to determine the starting mode of motion time for specific vehicles. Based on the obtained dependences of the internal pressure and temperature of the tire on time, it is necessary to evaluate how the rolling resistance coefficient changes. Methodology. As a result of experimental studies, on vehicles equipped with tires of various sizes and seasonality, the dependences of the pressure and temperature of the tire material at three points (tread zone, shoulder part and sidewall) were obtained. Using the results of the experiment, as well as based on the dependencies presented in scientific papers devoted to the study of the performance characteristics of car tires, an indirect assessment of the rolling resistance coefficient when driving in the starting mode is made. Results. The value of the increase in the internal pressure of the gas filler in the tire has been established and the driving time for the studied vehicles in the starting mode has been determined. The most intense temperature rise is observed in the shoulder area of the tires. The temperature of the surface layer of winter tires increases less than summer tires, and, accordingly, driving on winter tires is safer at temperatures close to 0°C and below. Originality. A technique for indirectly assessing the rolling resistance of a car tire when driving in the starting mode (on "cold" tires) is presented, that is, knowing how the internal air pressure and tire temperature change, it is possible to predict a change in the rolling resistance coefficient. Practical value. Using the dependences obtained as a result of an indirect assessment of the rolling resistance of car tires, one can judge the value of the rolling resistance coefficient without resorting to experiments. The well-known assertion that it is necessary to timely replace summer tires with winter ones (when the ambient temperature can reach +5 ° C and lower) is confirmed, thereby significantly improving road safety.

Subsidence above gas storage in salt caverns predicted with viscoelastic theory

Based on the on-site monitoring data, the surface subsidence in the Jintan underground gas storage site has occurred continuously since the construction and operation of gas storage engineering. Therefore, the prediction of surface subsidence above gas storage in salt caverns is important to ensure the long-term safety of gas storage. Based on the mechanics theory, the formulas of elastic deformation of spherical and cylindrical caverns are derived. The Burgers viscoelastic model is used to describe the creep of rock salt. The viscoelastic analytical solution of the cavern deformation is obtained by using the correspondence principle in viscoelastic theory. It is assumed that the volume of the surface subsidence basin is directly proportional to the shrinkage volume of the cavern. The surface subsidence distribution curve is described by a Gaussian function. The spatiotemporal prediction of surface subsidence above gas storage in salt caverns based on viscoelastic theory is thus developed. The proposed theoretical model is used to analyze the surface subsidence above a gas storage cavern in rock salt in Jintan. The calculated subsidence is compared with the monitoring data. The accuracy of the theoretical model is verified by numerical simulation. The theoretical model can be used to predict the surface subsidence considering the solution stage in which the internal pressure changes with time. Results of this paper can provide guidance and suggestions for engineering practice of gas storage in salt caverns.

Design and analysis of 5 kW helium turbine for EAST cryoplant

The helium turbine is an important core component in the refrigerator, which provides support and guarantee for the stable operation of the cryogenic system. This paper refers to the parameters of one of the four helium turbines in EAST, designs a 5 kW helium turbine. The overall structure of the turbine has been described, and the design and analysis of the impeller and bearing have been carried out. Through CFD analysis, the internal pressure and temperature change law of the flow is analyzed. The variable-condition operating characteristics of the turbine are predicted, and it is found that the turbine can maintain efficient operation within a wide range of mass flow changes. The bearing performance is calculated by solving the Reynolds equation. After determining the optimal bearing clearance 28 μm based on the principle of maximum stiffness, bearing performance parameters of load capacity and stiffness can be further calculated.

Destruction of a protective pipe coating under cyclic loading by internal pressure

An analytical method has been developed for determining the moment of destruction of thin pipe coatings whose material retains elasticity during cyclic changes in internal pressure. The coating material has the property of strain softening, that is, destruction with increasing deformation occurs as stresses drop. The properties of the coating material are described by a convex-concave potential. Due to damage accumulation resulting from fatigue loading, the properties of the coating material change. Hence, the complete deformation curve degenerates. To determine the moment of destruction, the methods of the mathematical theory of catastrophes are used, which make it possible to find all the equilibrium positions of the system and the point of instability of the deformation process. Due to the degeneration of the properties of the coating material, the catastrophe (loss of stability) approaches the parameters of fatigue loading.

Stress Analysis of the Effect of Additional Load on the Butt Weld of Suspended Pipeline With Variable Wall Thickness

Under the special geological environment of the buried pipe, the ground is lost at the bottom of the pipe, which is created by various kinds of external factors. The pipe in the suspended state would be greatly deformed due to its own weight, internal pressure, and other factors, resulting in the failure of the pipeline. When a variable wall thickness weld occurs in the suspended section of the pipeline, the change of the pipeline stress will be more complicated and changeable. In this study, ABAQUS software is used to establish a pipe–soil model of variable wall thickness butt welds of suspended pipelines. The axial stress distribution with different affected factors in the pipe, the change of curvature, and Mises stress change of the entire pipe along the axial direction are obtained by analyzing the internal pressure, wall thickness ratio, suspended length, weld position, and cone length. The results show that the stress at the root of the weld changes significantly; therefore, the weld has a greater impact on the stress of the entire pipeline. The change of internal pressure has little effect on the stress at the pipe weld. As the suspended length increases, the change in stress at the weld is more obvious. When the weld seam is close to the soil, the support of the soil will gradually shift the maximum stress position of the pipe from the top of the pipe to the bottom of the pipe. With the increase in cone length, it will reduce the sudden change of pipe section and the change in stress effectively. The places where the curvature greatly changes along the axial direction are at the pipe–soil separation and the middle of the pipeline, while the stress reaches the maximum at the pipe–soil separation, and the place with the largest stress change is the weld in the middle of the pipeline.

Start-up visualization and performance of flat-plate CLPHP based on PEMFC cooling

Aiming at the structural characteristics and heat dissipation requirements of proton exchange membrane fuel cell (PEMFC), the passive flat-plate CLPHP cooling is proposed, and its start-up heat transfer performance is studied. A visual start-up experiment is carried out by bonding high-borosilicate glass with a 2 mm thick aluminum alloy plate which has a 2.3 mm × 1.4 mm rectangular flow channel. The vapor-liquid flow variation rules in the evaporation section when the temperature is stable and the filling ratio (FR) is 40% and 50% under different heating powers are photographed. Meanwhile, the temperature of each section and internal pressure changes of the flat-plate CLPHP are also collected. It is found that under lower heating power, the evaporation section pushes the liquid slug to move slowly under the action of the vapor pressure generated by the evaporation of the liquid film, and the edge flow channel starts to flow first. The temperature of the evaporation section rises as the heating power increases, with the bottom of the elbow first nucleating and boiling to produce bubbles and gradually transforming from slug flow to semi-annular/annular flow, and the heat transfer power is enhanced. The FR40% has better start-up performance, and the heat transfer power is higher than FR50%.

Understanding the Geodetic Signature of Large Aquifer Systems: Example of the Ozark Plateaus in Central United States

AbstractThe continuous redistribution of water involved in the hydrologic cycle leads to deformation of the solid Earth. On a global scale, this deformation is well explained by the loading imposed by hydrological mass variations and can be quantified to first order with space‐based gravimetric and geodetic measurements. At the regional scale, however, aquifer systems also undergo poroelastic deformation in response to groundwater fluctuations. Disentangling these related but distinct 3D deformation fields from geodetic time series is essential to accurately invert for changes in continental water mass, to understand the mechanical response of aquifers to internal pressure changes as well as to correct time series for these known effects. Here, we demonstrate a methodology to accomplish this task by considering the example of the well‐instrumented Ozark Plateaus Aquifer System (OPAS) in the central United States. We begin by characterizing the most important sources of groundwater level variations in the spatially heterogeneous piezometer dataset using an Independent Component Analysis. Then, to estimate the associated poroelastic displacements, we project geodetic time series corrected for hydrological loading effects onto the dominant groundwater temporal functions. We interpret the extracted displacements in light of analytical solutions and a 2D model relating groundwater level variations to surface displacements. In particular, the relatively low estimates of elastic moduli inferred from the poroelastic displacements and groundwater fluctuations may be indicative of aquifer layers with a high fracture density. Our findings suggest that OPAS undergoes significant poroelastic deformation, including highly heterogeneous horizontal poroelastic displacements.

Containment Liner Plate Void Defect Detection Technique Using Phased Array Ultrasonic Testing and Acoustic Resonance Method.

The CLP (containment liner plate) of a nuclear power plant protects the internal system from the external environment and sudden changes in internal pressure or temperature, and it is a structure that blocks and protects radioactive materials leaking inside and outside in the event of a nuclear accident and is composed of a liner plate, reinforcing bars, tendons, and concrete. Recently, corrosion on the rear side of the liner plate and concrete voids has emerged as a severe defect in nuclear power plants across South Korea. Therefore, in this study, we proposed a new inspection method that a line-type inspection method applied phased array ultrasonic testing and the area inspection method applied acoustic resonance method using developed moveable tapper. The acoustic signals were signal-processed and reproduced to a mapping image following the inspection area, and with the image, it was possible to determine the type of defect. Furthermore, an automated inspection system for within the CLP was proposed.

亜急性期の大動脈解離におけるフラップ可動性が偽腔内の圧力場および流れ場に与える影響

亜急性期の大動脈解離におけるフラップ可動性が偽腔内の圧力場および流れ場に与える影響

Study on wellbore annular sealing technology based on the influence of fracturing operation in low permeability oilfield

At present, the fracturing technology has been very mature and is widely used in oil and gas field production operation. However, the fracturing operation will cause periodic changes in wellbore internal pressure and generate alternating stress. Due to the material factors of casing and cement sheath, the deformation of the two is inconsistent after stress, and then the damage of cement sheath and the failure of wellbore annulus seal occur. After water injection development, it is easy to produce channeling risk, so the performance of cement sheath is crucial. In view of this problem, through the theoretical analysis, experimental analysis and organic combination analysis of wellbore annulus cement ring sealing, the critical failure threshold of wellbore annulus cement ring under fracturing operation is given, which provides certain guidance for improving wellbore annulus sealing and reducing the risk of channeling after fracturing operation in the future.

Characteristics of the Received Signal of an Ultrasonic Sensor Installed in a Chamber with Micro-Leakage

Abstract. As fossil fuel depletion and environmental pollution problems are becoming increasingly more serious, interest in the efficient use of natural resources and alternative energy is rapidly growing. In particular, interest in fuels stored as high-pressure gases such as natural gas and hydrogen is also rising. Ultrasonic waves show various received signals according to characteristics such as density of the medium and acoustic impedance. An experimental study on the detection of the micro-leakage of fuel stored as high-pressure gas was conducted based on the characteristics of ultrasonic waves. First, an ultrasonic sensor was manufactured by selecting the matching layer with consideration of the acoustic impedance. In the experiment, a mass flow controller (MFC) was attached to a perforated hole in the fabricated chamber to generate micro-leakage, and the signal from the receiving ultrasonic sensor was then collected. The envelope signal of the received ultrasonic sensor signal was analyzed through the Gaussian distribution method. The temperature inside the chamber and the received voltage decreased according to a similar trend and showed a nonlinear result. However, the phase of the received ultrasonic sensor signal showed a relatively linear result according to the internal pressure change. Micro-leakage could not be detected with only the received voltage seen by the ultrasonic sensor. Therefore, the phase shift of the receiving ultrasonic sensor can be used to detect micro-leakage in a high-pressure gas tank.

Theoretical analysis on bubble radius and pressure fluctuation during steam bubble condensation

The pressure oscillation and condensation behavior of steam bubbles at low steam mass flux are experimentally and theoretically studied in this work. Based on the synchronous measurement system of bubble behavior and pressure oscillation, it is found that the steam bubble condenses first and then expands and contracts, the water pressure reaches the maximum (about 13 kPa) when the bubble condenses to the minimum radius (about 1 mm). Subsequently, taking into account the movement of the bubble and the change of internal pressure during the bubble condensation process, a theoretical model of heat and mass transfer in the bubble condensation process is established, which shows that the steam bubble collapse is caused by heat transfer and the bubble internal pressure fluctuation. In the early condensation process of steam bubble, the bubble internal pressure continues to increase, meanwhile, the influence of bubble internal pressure on bubble condensation continues to increase. During the later expansion and contraction process of the bubble, the bubble internal pressure decreases first and then increases, the bubble behavior is mainly controlled by the bubble internal pressure.

Cell Design Consideration Concerning Cell Failure Mechanism

Thermal swelling and dimension-changing properties of the LiB (Lithium-ion battery) cell during the cycle (charging/discharging) and aging are well-known LiB's intrinsic characteristics. These inherent properties are caused by expansion/contraction of electrode materials due to lithium-ion intercalation, irreversible reaction deposits changing/increasing the volume, and the cell internal pressure changes by decomposition and gas generation. The cell designer's fundamental phenomena should be fully understood and implicated in the cell design and manufacturing process. As the LiB energy density increases, the safety zone/concept of a cell model considering LiB's natural phenomena is getting diminished and minimized.This paper analyzed the effect of the thermal swelling and dimension-changing properties of LiB cell on cell safety and studied the cell safety mechanism related to the cell design, considering the thermal swelling and dimension-changing properties of LiB cell. We used the electrode alignment and overhang of the electrode assembly (the gaps between the end of the separator and the end of the anode, and between the end of the anode and end of the cathode). Some cell models increased their energy density by sacrificing their safety zone, minimizing the gaps among separator – anode - cathode.We analyzed the relationship between the electrode alignment and overhang of the electrode assembly and the battery safety. We measured the electrode alignment and gaps among separator-anode-cathode with the microscope measurement technology and applied the electrical, thermal, and mechanical trigger factors to the cell models.Experimental results identified that the status of the electrode alignment and gaps among separator-anode-cathode effect to the cell safety for all the tests of the electrical, thermal, and mechanical trigger factors. We develop and propose a cell safety mechanism from the relationship between the electrode alignment and gaps among separator-anode-cathode and the cell safety. Figure 1

Stable Cycling of All‐Solid‐State Batteries with Sacrificial Cathode and Lithium‐Free Indium Layer

AbstractAll‐solid‐state batteries (ASSBs) comprising solidified cathodes, electrolytes, and Li–metal anodes have attracted notable attention as promising future batteries for electric vehicles owing to their exceptional stability and expectation of achieving high energy density. However, its permanent operation has been hindered by Li dendrite growth, chemo–mechanical degradation, and interfacial instability, leading to Li exhaustion, increased resistance, and internal short‐circuiting. Herein, for the first time, the authors report the effects of a lithium nitride (Li3N) sacrificial cathode on the cycling performance of ASSBs combined with a Li‐free In layer. Through in situ evolved gas and internal pressure change analyses of the cells, it is found that, as with the liquid electrolyte cell, the decomposed Li3N compensates for active Li consumed by side reactions in the cell. Moreover, it is demonstrated that the improved interparticle contact by volume expansion of In through additionally supplied Li as well as the interfacial stability at the anode side by the dendrite‐free In layer, are strongly responsible for the improved cyclability of the ASSBs. The findings reveal the effectiveness of the Li compensation approach for the stable cycling of ASSBs based on the secured interfacial stability at the anode side.

Experimental Investigation on the Operating Characteristics of Flat-Plate CLPHP for PEMFC Cooling

Proton exchange membrane fuel cell (PEMFC) generates electricity through hydrogen and oxygen chemical reaction with the generation of much heat. According to the working temperature of PEMFC, the thermal resistance and internal relative pressure change of the flat-plate micro closed-loop pulsating heat pipe (CLPHP) are tested and analyzed at different filling ratios, vacuum degrees, and inclination angles, whose working medium is binary methanol-deionized water with a mass ratio of 5:1. The experiment results show that the higher the vacuum degree is, the better the startup and heat transfer performance of CLPHP become; the thermal resistance is less sensitive to inclination angle except for horizontal placement; the 40% volume-filling ratio can effectively avoid dry-out at high temperature. When 80 °C is the ideal working temperature of PEMFC, the thermal resistance of CLPHP is 0.093°C/W; the heat transfer heat flux is 1.59 W/cm2, and the temperature fluctuation is small. Therefore, flat-plate CLPHP has great application potential for PEMFC cooling.

Nonlinear static response of an underwater elastic toroidal storage container

This paper investigates the behaviour of an underwater elastic toroidal shell storage container filled with compressible fluid under constraint volume condition. The fundamental form of the surface is used to define the geometry of a toroidal shell under an initial unstrained state (IUS), reference state (RS), and deformed state (DS). In the reference state, it is assumed that the toroidal shell storage container has a circular cross section. In the deformed state, the displacements of the shell are assumed to be large. The energy functional of the underwater toroidal shell storage container can be established based on the principle of virtual work, and it can be rearranged in an appropriate form that can conveniently be implemented in a finite element formulation. The nonlinear static analysis of the elastic toroidal storage container under external hydrostatic pressure can be performed by the nonlinear finite element method (FEM) via the fifth-order polynomials shape functions. The nonlinear responses under the variable water depth to cross-sectional radius, cross-sectional radius to wall thickness, and cross-sectional bend radii ratio are demonstrated and discussed. The results revealed that the change of internal pressure is indicated by the value of the Lagrange multiplier, which is calculated using the iterative method for finding the equilibrium configuration under the constraint volume requirement.

Modeling changes in internal pressure during the solidification of hydrous granitic intrusives: Implications for the crystallization of miarolitic pegmatites

ABSTRACT Volatile exsolution is widely recognized as an important trigger for eruptions from shallow magma reservoirs, but relatively few studies quantify the effects of exsolution on internal pressure within deeper-seated intrusive bodies. We present a model to predict internal pressure changes during the crystallization of a haplogranite melt containing 3 and 5 mass % H2O and with an emplacement pressure of 200 MPa. Mass and volume relations between phases are used to determine internal pressure assuming a closed, constant-volume system. The results indicate that initial crystallization of alkali feldspar and quartz causes a decrease in pressure prior to the exsolution of an aqueous fluid from the residual melt (i.e., resurgent boiling). Further crystallization toward the core of the body in the presence of a separate volatile phase results in a sharp increase in internal pressure. Our model shows that in closed, isochoric systems, the crystallization of the H2O-saturated melt will generate internal pressures that greatly exceed emplacement pressures typical of miarolitic pegmatites. Extreme overpressure modifies the physical and chemical properties of the residual melt and coexisting aqueous fluid, which in turn influences crystallization kinetics and the development of primary textures. Primary melt and fluid inclusions in pocket minerals thus likely represent samples trapped at various pressures in a rapidly evolving melt–fluid system. In most pegmatites, increasing fluid pressure and the formation of large pockets is regulated by the permeability and tensile strength of the enclosing rock. This explains why many miarolitic pegmatites occur within rigid host rocks such as granite, gabbro, and gneiss.

A complete analytical solution for axial pipeline walking considering seabed resistance as rigid plastic behaviour

Offshore pipelines are important infrastructure for transporting oil and gas. They are subjected to cycles of high temperature and pressure variation during operation and shutdown periods, and are therefore susceptible to the stability problem of axial walking due to the asymmetry between the expansion and contraction. Axial walking can cause damage to subsea pipeline systems, for instance to the connected manifolds and steel catenary risers. This paper provides a complete analytical solution to examine the process of pipeline walking based on underlying principles of mechanics, considering the pipeline–seabed sliding response as rigid plastic. The analytical solution allows calculation of the cumulative displacement, strain, axial force and soil resistance along the pipeline under arbitrary temperature or internal pressure change histories, accounting for the coupled contributions from seabed slopes and end tension forces. A dimensionless parameter η is proposed to explain the triggering mechanism for walking by comparing the activating force to the soil resistance. New criteria are established to judge whether pipeline axial walking is possible. Calculation examples are presented in the final part of this paper to demonstrate the analytical solution. This study can be used as a rigorous benchmark and a simple practical tool to evaluate pipeline walking under arbitrary loading histories of temperature and internal pressure variations.

Mechanical effects of circular liquid inclusions inside soft matrix: role of internal pressure change and surface tension

The mechanical effects of dilute liquid inclusions on the solid-liquid composite are explored, based on an analytical circular inclusion model incorporating the internal pressure change of the liquid and the surface tension of the interface. Several simple explicit dependences of the stress field and effective stiffness on the bulk modulus and the size of the liquid, the surface tension, and Poisson’s ratio of the matrix are derived. The results show that the stresses in the matrix are reduced, and the stiffness of the solid-liquid composite is enhanced with the consideration of either the surface tension or the internal pressure change. Particularly, the effective Young’s modulus predicted by the present model for either soft or stiff matrices agrees well with the known experimental data. In addition, according to the theoretical results, it is possible to stiffen a soft solid by pressured gas with the presence of the surface tension of the solid-gas interface.

Effects of Left Ventricular Hypertrophy and Myocardial Stiffness on Myocardial Strain Under Preserved Ejection Fraction.

Despite numerous experimental observations regarding heart failure with preserved ejection fraction (HFpEF), which is characterized mainly by left ventricular hypertrophy and a left ventricular ejection fraction over 50%, myocardial dynamics under HFpEF have not yet been fully clarified, particularly regarding the relationship between myocardial strain distribution and myocardial work. To address this issue, we numerically investigated radial distribution of myocardial strain during a cardiac cycle with fixed internal volume at the end of the systolic and diastolic phases under different mechanical conditions, such as those involving myocardial thickness and elasticity of myocardial fibers. The myocardium was a modeled as a visco-hyperelastic continuous material. This model was taken into account that active contractile stress along the myocardial fiber direction depends on membrane potential change. Our numerical results showed that both radial and circumferential strains decreased as wall thickness increased, which reflected cardiac hypertrophy, but that myocardial work became larger than that observed with thin ventricular walls. Further, the change in left ventricular diastolic internal pressure caused circumferential strain, while fiber stiffness contributed to radial strain. Since peak circumferential strain was well estimated by the maximum difference between total internal and myocardial volumes, measuring the epicardial contraction rate should be helpful in understanding patients with HFpEF.