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Journal articles on the topic 'Pressure chamber'
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1
Danilatos, Gerasimos D. "Reverse Flow Pressure Limiting Aperture." Microscopy and Microanalysis 6, no. 1 (January 2000): 21–30. http://dx.doi.org/10.1017/s1431927600000052.
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The reverse flow pressure limiting aperture is a device that creates and sustains a substantial gas pressure difference between two chambers connected via an aperture. The aperture is surrounded by an annular orifice leading to a third chamber. The third chamber is maintained at a relatively high pressure that forces gas to flow through the annular aperture into the first of said two chambers. The ensuing gas flow develops into a supersonic annular gas jet, the core of which is coaxial with the central aperture. A pumping action is created at the core of the jet and any gas molecules leaking through the aperture from the second chamber are entrained and forced into the first chamber, thus creating a substantial pressure difference between the first and second chamber.
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Danilatos, Gerasimos D. "Reverse Flow Pressure Limiting Aperture." Microscopy and Microanalysis 6, no. 1 (January 2000): 21–30. http://dx.doi.org/10.1007/s100059910002.
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Abstract The reverse flow pressure limiting aperture is a device that creates and sustains a substantial gas pressure difference between two chambers connected via an aperture. The aperture is surrounded by an annular orifice leading to a third chamber. The third chamber is maintained at a relatively high pressure that forces gas to flow through the annular aperture into the first of said two chambers. The ensuing gas flow develops into a supersonic annular gas jet, the core of which is coaxial with the central aperture. A pumping action is created at the core of the jet and any gas molecules leaking through the aperture from the second chamber are entrained and forced into the first chamber, thus creating a substantial pressure difference between the first and second chamber.
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Wang, Chuan-hao, Shu-shan Wang, Jing-xiao Zhang, and Feng Ma. "Pressure Load Characteristics of Explosions in an Adjacent Chamber." Shock and Vibration 2021 (January 21, 2021): 1–9. http://dx.doi.org/10.1155/2021/3726306.
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To learn more about dynamite explosions in confined spaces, we focused on the chamber adjacent to the main chamber, the main chamber being the location of the explosion. We investigated the characteristics of two damaging pressure loads: first reflected shock wave and quasistatic pressure. In this work, we analyzed the characteristics of the first reflected shock wave and the quasistatic pressure formed by the explosion of the chamber charge. Simulated chamber explosion experiments were carried out, where high-frequency piezoelectric sensors were used to measure the first reflected shock wave, and low-frequency piezo-resistive sensors were used to measure the quasistatic pressure. Valid and reasonable experimental data were obtained, and the experimental values of the pressure load were compared with those calculated from the classical model. The results showed that when the main chamber was partially damaged by the explosion load, the adjacent chambers were not subjected to the shock wave load, and the quasistatic pressure load was less than that in the main chamber. The presence of adjacent chambers did not affect the shock wave load in the main chamber. Using the mass of the explosive and the blast distance as input parameters, the internal explosion shock wave load parameters, including those in adjacent chambers, can be calculated. The presence of the adjacent chamber did not affect the theoretically calculated quasistatic overpressure peak in the main chamber. Using the mass of the explosive and the spatial volume of the chamber as input parameters, the quasistatic pressure load parameters of the internal explosion can be calculated, including those in the adjacent chambers.
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Segers, Patrick, Jean-Paul Belgrado, Andre Leduc, Olivier Leduc, and Pascal Verdonck. "Excessive Pressure in Multichambered Cuffs Used for Sequential Compression Therapy." Physical Therapy 82, no. 10 (October 1, 2002): 1000–1008. http://dx.doi.org/10.1093/ptj/82.10.1000.
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Abstract Background and Purpose. Pneumatic compression devices, used as part of the therapeutic strategy for lymphatic drainage, often have cuffs with multiple chambers that are inflated sequentially. The purpose of this study was to investigate (1) the relationship between cuff chamber pressure (Pchamber) and the pressure on the cuff-skin interface (Pinterface) and (2) the mechanical interaction of cuff chambers and consequences for device control. Subjects and Methods. In this study, we used 3 cylindrical (60-, 80-, and 100-mm-diameter) model limbs and 1 ellipsoidal model of the arm to test a commercially available pressure controller using “target pressures,” indicated by the controller, of 30, 60, 80, and 100 mm Hg. We studied the time course of Pchamber and Pinterface during the inflation sequence and the effect of local curvature on Pinterface. Results. Our data indicated that, overall, Pinterface is of the same order of magnitude as Pchamber. There was some effect of model diameter and shape, with the smaller curvatures yielding the highest Pinterface. Cuff chamber interaction led to Pchamber and Pinterface values in the most distal (first inflated) chamber that were up to 80% higher than the target pressure. For the 80-mm cylindrical model, for instance, pressure in this chamber reached 54, 98, 121, and 141 mm Hg, respectively, instead of the 30, 60, 80, and 100 mm Hg indicated by the controller. Discussion and Conclusion. The discrepancy between the target pressure, indicated by the controller, and the pressure measured inside the cuff chambers undermines the therapeutic control and efficacy of the pneumatic compression devices. Because the measured pressures were far beyond the pressure level indicated by the controller, it is recommended that pneumatic compression devices be used at much lower target pressures (<30 mm Hg) than those applied in clinical practice.
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Ho Cho, Seung, Olli Niemi-Pynttäri, and Matti Linjama. "Friction characteristics of a multi-chamber cylinder for digital hydraulics." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 5 (March 2, 2015): 685–98. http://dx.doi.org/10.1177/0954406215575414.
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This paper deals with the issue of defining friction characteristics of a multi-chamber cylinder for digital hydraulics. Using a multi-chamber cylinder under a set of supply pressures, friction characteristics are experimentally investigated for a range of velocity according to load conditions. A binary digit-based pressure e.g., high pressure or low pressure has been applied to each chamber. The friction force is measured based on the equation of motion using measured values of the pressures in the chambers of the multi-chamber cylinder and the position of the piston. As a mechanism to load the multi-chamber cylinder, a 1-Degree of Freedom (DOF) boom mockup mimicking a medium-sized mobile machine boom has been constructed. Then it has been utilized to test the motion of the cylinder under different mass–load conditions. It is shown that the cylinder states do not dominantly affect the friction force of a multi-chamber cylinder, comparing the effect of other parameter such as mass load and velocity, which is expected to be useful for the secondary control of digital hydraulic systems.
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Raine, N. M., and N. T. Cable. "A simplified paired neck chamber for the demonstration of baroreflex blood pressure regulation." Advances in Physiology Education 277, no. 6 (December 1999): S60. http://dx.doi.org/10.1152/advances.1999.277.6.s60.
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In this investigation a simplified variable-pressure paired neck chamber was developed as a practical alternative to traditional neck collar designs used to study the arterial baroreceptor reflex in humans. The purpose of this new design was to extend the use of the noninvasive neck chamber method of baroreceptor investigation to teachers of physiology. Performance tests indicate that these new chambers are capable of delineating the stimulus-response relationship for both the blood pressure baroreflex [sensitivity = 0.425 +/- 0.13 mmHg mean arterial pressure (MAP)/mmHg neck chamber pressure (NCP); range = 24.9 +/- 4.6 mmHg MAP] and the heart rate baroreflex (sensitivity 0.273 +/- 0.12 beats.min-1.mmHg NCP-1; range = 16.7 +/- 6.8 beats/min). This was achieved by applying localized positive and negative air pressures to the carotid sinuses throughout the range from +60 to -60 mmHg in steps of 20 mmHg. This simplified neck chamber method offers distinct methodological advantages over traditional neck collars, making it a valuable tool for demonstrating baroreflex regulation of the circulation.
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Šabacká, Pavla, Vilém Neděla, Jiří Maxa, and Robert Bayer. "Application of Prandtl’s Theory in the Design of an Experimental Chamber for Static Pressure Measurements." Sensors 21, no. 20 (October 15, 2021): 6849. http://dx.doi.org/10.3390/s21206849.
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Pumping in vacuum chambers is part of the field of environmental electron microscopy. These chambers are separated from each other by a small-diameter aperture that creates a critical flow in the supersonic flow regime. The distribution of pressure and shock waves in the path of the primary electron beam passing through the differentially pumped chamber has a large influence on the quality of the resulting microscope image. As part of this research, an experimental chamber was constructed to map supersonic flow at low pressures. The shape of this chamber was designed using mathematical–physical analyses, which served not only as a basis for the design of its geometry, but especially for the correct choice of absolute and differential pressure sensors with respect to the cryogenic temperature generated in the supersonic flow. The mathematical and physical analyses presented here map the nature of the supersonic flow with large gradients of state variables at low pressures at the continuum mechanics boundary near the region of free molecule motion in which the Environmental Electron Microscope and its differentially pumped chamber operate, which has a significant impact on the resulting sharpness of the final image obtained by the microscope. The results of this work map the flow in and behind the Laval nozzle in the experimental chamber and are the initial basis that enabled the optimization of the design of the chamber based on Prandtl’s theory for the possibility of fitting it with pressure probes in such a way that they can map the flow in and behind the Laval nozzle.
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Zhuravlyov, Yu N., S. N. Semyonov, J. N. Lukyanov, A. L. Perminov, S. I. Tikhonov, and M. A. Donchenko. "CALCULATION TEMPERATURE AND PRESSURE OF THE ROTARY ENGINE." Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference 3 (June 16, 2015): 223. http://dx.doi.org/10.17770/etr2015vol3.195.
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<p>The principles of calculating the temperature and pressure in the working chambers of the rotary vane engine with an external supply of heat are considered. The mathematical model for calculating the pressure and the temperature in the chamber with heat transfer between the working fluid and the chamber walls is built. The plots of the dependence of the pressure and the temperature in the chamber on the angle of rotation of the output shaft at the minimum and maximum temperature of the walls are obtained.</p>
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Hernandez, Francisco, Hong Hao, and Xihong Zhang. "On the effectiveness of ventilation to mitigate the damage of spherical chambers subjected to confined trinitrotoluene detonations." Advances in Structural Engineering 22, no. 2 (August 16, 2018): 486–501. http://dx.doi.org/10.1177/1369433218791610.
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This article presents a comparative study on the effectiveness of ventilation to mitigate blasting effects on chambers subjected to confined detonations of high explosives. The pressure time-history that acts on the chamber walls is described by three components: (1) the first shock wave, (2) the train of re-reflected shock waves, and (3) the gas pressure. The radial response of spherical chambers is described by the radial breathing mode and modeled by an equivalent single degree of freedom system. The three pressure components are considered for the calculation of the maximum ductility ratio, which is obtained from the numerical solution of the single degree of freedom chamber response. It is assumed that openings reduce the gas pressure but they have an insignificant effect on shock waves. The dynamic response of fully and partially confined chambers are calculated and compared. Results show that intermediate/small openings (less than 10% of the surface of the chamber) are ineffective to mitigate the chamber response and damage. The vibratory response of the chamber is susceptible to elastic or plastic resonance but it is not considerably modified by the long-term gas pressure because of its high radial breathing mode frequency, allowing concluding that ventilation is ineffective to reduce the maximum response of spherical chambers subjected to internal high explosive explosion.
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Kim, Hanseup, Khalil Najafi, and Luis P. Bernal. "Helmholtz Resonance Based Micro Electrostatic Actuators for Compressible Gas Control: A Microjet Generator and a Gas Micro Pump." Journal of Microelectronics and Electronic Packaging 7, no. 1 (January 1, 2010): 1–9. http://dx.doi.org/10.4071/1551-4897-7.1.1.
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This paper reports Helmholtz-resonance based micro electrostatic actuators to control compressible gaseous fluids in the micro scale. Particularly, it discusses design, fabrication, and testing results of two electrostatic actuators: a micro jet generator and an integrated peristaltic multistage micro pump. These electrostatic actuators vibrate a micro membrane in a micro chamber at a high frequency (>10 kHz), and easily induce the resonant behavior of compressible gases in the chamber. Such resonant behavior, often called the Helmholtz resonance, can repeatedly create instantaneous pressure in equilibrium between the inside and outside of the chamber and cause gas to rapidly exit the chamber, forming a collimated jet. The developed micro jet generator consists of multiple acoustic chambers in parallel; produces directional gas momentum from each chamber by utilizing the Helmholtz resonance; and collectively entrains nearby gas molecules to form a gas stream. The fabricated micro jet generator has a footprint of 1.6 × 1.6 cm2 and contains 25 acoustic micro thrusters. It operates using a 140 V and 70 kHz sinusoidal signal and produces a thrust of 55.6 μN, a maximum air velocity of 1.2 m/s, and consumes power of 3.11 mW. The developed micro pump consists of multiple acoustic chambers in series and produces a high total pressure by accumulating pressures across the multiple chambers, while maintaining high flow rates utilizing the fluidic resonance of each pumping chamber. The fabricated 18-stage pump produces the maximum air flow rate of 4.0 sccm and maximum pressure differentials of 17.5 kPa with total power consumptions of only 57 mW. Its total package volume is 25.1 × 19.1 × 1 mm3. It is notable that these electrostatic actuators, with their actuation membranes, acoustic chambers, fluidic channels, and micro valves, are fabricated into a single silicon chip by developing low temperature wafer bonding techniques to protect the polymer structures inside.
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Qi, Yuanjie, Yuqiang Cheng, and Yan Zhang. "Life Analysis of Reusable Liquid Rocket Engine Thrust Chamber." Aerospace 9, no. 12 (December 2, 2022): 788. http://dx.doi.org/10.3390/aerospace9120788.
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The thrust chamber’s inner wall suffers high temperature and pressure differences from the coolant channel, which limits the life of the rocket engine. Life prediction of the thrust chamber really plays an important role in reusable launch vehicle propulsion systems. The Porowski beam model is widely used in the life prediction of reusable liquid rocket engine thrust chambers, which calculates the life caused by fatigue, creep, and thinning after each firing cycle. In order to analyze the life of the thrust chamber, a LOX/Kerosene rocket engine is investigated in this paper. The life analysis consists of pressure and temperature differences and structural parameters. Two kinds of inner wall materials were chosen for comparison in this research: OFHC copper and Narloy-Z alloy. The results are presented to offer a reference for the design and manufacture of reusable rocket engine thrust chambers in the future.
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Kitahara, Masaaki, Akira Kodama, Hiroshi Ozawa, and Shuzo Inoue. "A Soundproof Pressure Chamber." Acta Oto-Laryngologica 114, sup510 (January 1994): 82–86. http://dx.doi.org/10.3109/00016489409127309.
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Jacobson, B. O. "High-pressure chamber measurements." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 220, no. 3 (March 2006): 199–206. http://dx.doi.org/10.1243/13506501jet133.
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Cumbo-Nacheli, Gustavo, Diego Conci, and James Smith. "Negative Pressure Aerosol Chamber." Journal of Bronchology & Interventional Pulmonology 28, no. 1 (December 14, 2020): e7-e10. http://dx.doi.org/10.1097/lbr.0000000000000695.
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Oxford Cryosystems. "Portable xenon pressure chamber." Acta Crystallographica Section D Biological Crystallography 55, no. 3 (March 1, 1999): 724. http://dx.doi.org/10.1107/s0907444999003686.
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Kitahara, Masaaki, Akira Kodama, Hiroshi Ozawa, and Shuzo Inoue. "Sound-Proof Pressure Chamber." Practica oto-rhino-laryngologica. Suppl. 1993, Supplement66 (1993): 68–74. http://dx.doi.org/10.5631/jibirinsuppl1986.1993.supplement66_68.
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Oxford Cryosystems. "Portable xenon pressure chamber." Journal of Applied Crystallography 32, no. 2 (April 1, 1999): 379. http://dx.doi.org/10.1107/s0021889899003878.
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Oh, Sang-Ho, and Chang-Hwan Ji. "WAVE PRESSURE FORMULA FOR PERFORATED CAISSON WITH DOUBLE CHAMBERS." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 34. http://dx.doi.org/10.9753/icce.v36.structures.34.
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Some of perforated caisson breakwaters have double wave chambers, for which no clear guideline for estimating design load is available. The well-known Takahashi's formula (Takahashi and Shimosako, 1994) is basically applicable to single-chamber perforated caisson. Considering this, we conducted physical experiment to develop a wave pressure formula for double-chamber perforated caisson.
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Shao, Bing. "Load Model of Small Parameter Scroll Wrap for Bending Fatigue Strength in a Scroll Compressor." Advanced Materials Research 199-200 (February 2011): 92–96. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.92.
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The pressures and the temperatures in compression chambers are analyzed, and a load model including the pressure loads and the temperatures is proposed. For the small parameter scroll wraps, the pressure loads can be simplified on the mid-areas and the temperatures are equal to the temperatures of the mid-areas. The pressure loads are of π-region pressures which have a normal angle interval of π, the number of acting regions for pressure loads is equal to the number of scroll compression chamber pairs. Apart from the part situated in the center compression chamber, the temperatures of scroll wrap decrease linearly with the normal angle. Selecting the reasonable discharge, specifying the appropriate material and the parameters, and modifying the starting part of scroll wrap are significant methods to improve fatigue strength of scroll wraps in practice.
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Križan, Peter, Miloš Matúš, and Juraj Beniak. "RELATIONSHIP BETWEEN COMPACTING PRESSURE AND CONDITIONS IN PRESSING CHAMBER DURING BIOMASS PRESSING." Acta Polytechnica 56, no. 1 (February 29, 2016): 33. http://dx.doi.org/10.14311/app.2016.56.0033.
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In this paper, we will present the impact of the conditions in pressing chambers during the pressing of wooden briquettes. The conditions in pressing chambers can significantly impact the resulting compacting pressure required for the pressing of briquettes. In the introduction, we show which parameters of the pressing chamber during pressing can impact the resulting compacting pressure. The experiment results which are shown in this paper described the detected impact of some important pressing chamber parameters. This experiment aims to detect the pressing chamber length impact and the impact of the way of pressing. By setting the pressing conditions, we will be able to achieve the suitable resulting compacting pressure with respect to the required final briquettes quality.
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Bing, Shao. "The Strength Model of Small Parameter Scroll Wrap in a Scroll Compressor." Advanced Materials Research 415-417 (December 2011): 80–84. http://dx.doi.org/10.4028/www.scientific.net/amr.415-417.80.
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The paper analyzed the pressures and the temperatures in compression chambers for calculation of bending fatigue strength , and a strength model is proposed. For the small parameter scroll wraps, the pressure loads are of π-region pressures which have a normal angle interval of π, the number of acting regions for pressure loads is equal to the number of scroll compression chamber pairs. Apart from the part situated in the center compression chamber, the temperatures of scroll wrap decrease linearly with the normal angle. Selecting the reasonable discharge, specifying the appropriate material and the parameters, and modifying the starting part of scroll wrap are significant methods to improve fatigue strength of scroll wraps in practice.
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Pleskun, H., A. Syring, and A. Brümmer. "Transient chamber filling in rotary positive displacement vacuum pumps." IOP Conference Series: Materials Science and Engineering 1267, no. 1 (November 1, 2022): 012016. http://dx.doi.org/10.1088/1757-899x/1267/1/012016.
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Chamber model simulation is a common approach to simulate rotary positive displacement vacuum pumps. Therefore the pump is abstracted into working chambers and connecting clearances, whereby the clearance leakages can be identified as the major loss mechanism in such machines. The clearance mass flow rates are calculated with respect to the thermodynamic states in the adjacent chambers, which are inhomogeneous for rarefied gases due to the movement of the rotors which causes a pressure gradient within the chamber. This effect increases with higher Knudsen numbers, because of the increasingly dominant friction. It is shown that inhomogeneous chamber states cause a non-complete chamber filling. As a result the mass-averaged pressure within the suction chamber is lower than the pressure in the suction port. Due to the non-constant chamber volume over time three-dimensional transient simulations with a Computational Fluid Dynamics (CFD) solver are performed in order to investigate the mass within a geometrically abstracted suction chamber. Based on a dimensionless number, a regression analysis is done to provide a quantitative estimation of this effect by means of analytical calculations. This is implemented in a chamber model simulation software and results of a test machine are compared to measurements and to previous simulations.
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Koike, Fumiya, and Toshio Takayama. "Generation of Concentration Gradients by a Outer-Circumference-Driven On-Chip Mixer." Micromachines 13, no. 1 (December 31, 2021): 68. http://dx.doi.org/10.3390/mi13010068.
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The concentration control of reagents is an important factor in microfluidic devices for cell cultivation and chemical mixing, but it is difficult to realize owing to the characteristics of microfluidic devices. We developed a microfluidic device that can generate concentration gradients among multiple main chambers. Multiple main chambers are connected in parallel to the body channel via the neck channel. The main chamber is subjected to a volume change through a driving chamber that surrounds the main chamber, and agitation is performed on the basis of the inequality of flow caused by expansion or contraction. The neck channel is connected tangentially to the main chamber. When the main chamber expands or contracts, the flow in the main chamber is unequal, and a net vortex is generated. The liquid moving back and forth in the neck channel gradually absorbs the liquid in the body channel into the main chamber. As the concentration in the main chamber changes depending on the pressure applied to the driving chamber, we generated a concentration gradient by arranging chambers along the pressure gradient. This allowed for us to create an environment with different concentrations on a single microchip, which is expected to improve observation efficiency and save space.
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Shao, Bing. "The Study of Bending Fatigue Strength Model for Scroll Wraps." Applied Mechanics and Materials 52-54 (March 2011): 470–75. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.470.
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The paper analyzed the pressures and the temperatures in compression chambers to calculate the bending fatigue strength for small parameter scroll wraps, and a load model is proposed. For the small parameter scroll wraps, the pressure loads can be simplified on the mid-areas and the temperatures are equal to the temperatures of the mid-areas. The pressure loads are of π-region pressures which have a normal angle interval of π, the number of acting regions for pressure loads is equal to the number of scroll compression chamber pairs. Apart from the part situated in the center compression chamber, the temperatures of scroll wrap decrease linearly with the normal angle. Selecting the reasonable discharge, specifying the appropriate material and the parameters, and modifying the starting part of scroll wrap are significant methods to improve fatigue strength of scroll wraps in practice.
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Baum, M. R. "Pressure vessel rupture within a chamber: The pressure history on the chamber wall." Experimental Thermal and Fluid Science 4, no. 3 (May 1991): 265–72. http://dx.doi.org/10.1016/0894-1777(91)90044-r.
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Dvořák, Václav. "Air to Air Ejector with Various Divergent Mixing Chambers." Applied Mechanics and Materials 493 (January 2014): 50–55. http://dx.doi.org/10.4028/www.scientific.net/amm.493.50.
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The article deals with experimental investigation of subsonic air to air ejector with various configurations of the mixing chamber and the diffuser. A constant mixing chamber, 2° and 4° divergent mixing chambers and 6° diffuser were applied to find differences in the mixing process. Characteristics of the ejector, static pressure distributions and pressure fluctuations were measured to find how the different shape of the mixing chamber affect the efficiency of mixing processes. Pressure fluctuation increased rapidly while the ejection ratio was higher than 1.25 and the highest efficiency of the ejector was obtained when using configuration 4-4-6.
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Du, Fen, Bo Zhang, Chao Zhu, Zhiming Ji, and Chao-Hsin Lin. "Design and implementation of automatic control for a condensation-induced depressurization system." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 233, no. 9 (December 7, 2018): 1146–58. http://dx.doi.org/10.1177/0959651818816477.
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This study develops a control system to automate the operation of a condensation-induced depressurization technology, which is used to achieve sub-atmospheric pressure in an open-flow system on ground. The continuous depressurization is maintained via an integrated series of chambers inside which vacuum is regenerated by condensing and refilling of saturated steam. The low pressure generated inside the chambers is then used to alternatively extract the air out of a flow system for maintaining its sub-atmospheric pressure. The thermodynamic cycle in such a vacuum chamber consists of three sub-processes: air purging to ambient by steam refilling, depressurization by steam condensation, and air-extraction from a flow application. As one chamber undergoing these consecutive processes, another chamber operates in a coordinated different phase to seamlessly maintain a continuous air-extraction operation. This new system provides a quiet and efficient way of using low-grade energy to generate hypobaric environment for needed applications. A cascade arrangement of a proposed multiple-chamber operation is also illustrated. A control system is designed and implemented to realize the automatic and coordinated operation in a dual-chamber, laboratory-scaled system. Exemplified results on process characteristics such as chamber depressurization and air purging are also provided.
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Yin, Huadong, Daobing Zhang, Jiahua Zhang, Biao Yu, and Xiaomeng Yuan. "Reliability Analysis on Multiple Failure Modes of Underground Chambers Based on the Narrow Boundary Method." Sustainability 14, no. 19 (September 23, 2022): 12045. http://dx.doi.org/10.3390/su141912045.
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This paper proposes to study the stability of underground chambers while taking into account the nonlinear characteristics of geotechnical materials and pore water. According to the upper bound theorem of nonlinear limit analysis and the reliability theory, the failure mode and reliability model of underground chambers are established considering the pore water effect. The upper bound solution expression of the surrounding rock pressure in the underground chamber is deduced. The variation law of the surrounding rock pressure is analyzed under different parameters. At the same time, based on the narrow boundary method considering the correlation of multiple failure modes, the influence of different random parameters on the failure probability and reliability index of underground chambers is studied. The results show that the water-level line height, pore water pressure coefficient and Hoek-Brown failure criterion parameter have significant effects on the surrounding rock pressure and underground chamber reliability. In addition, the concept of the safety level is introduced, and the minimum-support force range of the underground chamber with safety level 1 is obtained under different random parameters. The research results can provide a theoretical basis and reference for the structural safety evaluation of underground chambers.
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Козел, Дмитрий Викторович. "Выбор геометрических характеристик фронтового устройства и длины камеры сгорания прямоточного типа." Aerospace technic and technology, no. 4sup2 (August 27, 2021): 19–28. http://dx.doi.org/10.32620/aktt.2021.4sup2.03.
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A method has been developed for selecting the geometric characteristics of the front and the length of the direct-flow combustion chamber. Afterburner combustion chambers are of the ramjet type and are used for a short-term increase in the thrust of a gas turbine engine during takeoff, for overcoming the sound barrier by an aircraft and for flying at supersonic speed, and for making maneuvers. As part of ramjet engines, ramjet combustion chambers are used as the main combustion chambers in which the process of fuel combustion and heat supply to the working fluid is ensured. The developed method for selecting the geometric characteristics consists in optimizing the main operating characteristics of the combustion chamber. Mathematical models are proposed for describing the dependence of the total pressure loss, the combustion efficiency and the range of stable operation of the combustion chamber against the parameters of the flow at the inlet to the combustion chamber and the geometric characteristics of the front device and the length of the combustion chamber. The analysis of the dependences of the combustion chamber working characteristics on the geometric characteristics of the front-line device and its length is carried out. As a result of the analysis of mathematical models, a list of the main geometric characteristics of the front device was determined, on which the total pressure loss, the combustion efficiency and the range of stable operation of the combustion chamber depend. Optimization parameters, optimization criterion and limits for solving the optimization problem are determined. As an implementation of the optimization method, it is proposed to use a diagram of the combustion chamber performance in the coordinates of the optimization parameters. The developed method makes it possible to ensure the optimal basic operating characteristics of the combustion chamber - total pressure loss, combustion efficiency and combustion stability limits.
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Osman, Akil, Simon De Meulemeester, Benny Malengier, Joris Degroote, and Jan Vierendeels. "Numerical prediction and experimental analysis of ends-together yarn splicing." Textile Research Journal 87, no. 12 (June 24, 2016): 1457–68. http://dx.doi.org/10.1177/0040517516654109.
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Pneumatic yarn splicing is a technical process for joining two yarn ends together. The process involves injecting compressed air into a splicing chamber. The inlet pressure and chamber slope determine the main parameters affecting this process. In this paper, large eddy simulation of the flow field in four selected splicing chambers is carried out. The chambers are used for splicing ends-together yarns. The results of these simulations are analyzed to investigate first the effects of the inlet pressure. Secondly, the effects of the geometry of the chambers on the flow field inside the splicing chambers are determined. These effects are studied and analyzed to interpret the experimental results, which have been obtained using the same splicing chambers. This provides further insight into the parameters that are important in order to obtain good splicing characteristics. It is demonstrated that the volume of the splicing chamber and the location of the air inlet channel play crucial roles in the splicing of the end-together yarns. The root mean square values of the velocity magnitude inside a splicing chamber have predictive values for the retained splice strength. The results provide solid evidence on the effectiveness of the computational fluid dynamics technology to study pneumatic splicing and optimize the geometry of an ends-together splicing chamber.
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Rajesh, T. N., T. J. S. Jothi, and T. Jayachandran. "Preliminary Studies on Non-Reactive Flow Vortex Cooling." Recent Patents on Mechanical Engineering 12, no. 3 (September 26, 2019): 262–71. http://dx.doi.org/10.2174/2212797612666190510115403.
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Background: The impulse for the propulsion of a rocket engine is obtained from the combustion of propellant mixture inside the combustion chamber and as the plume exhausts through a convergent- divergent nozzle. At stoichiometric ratio, the temperature inside the combustion chamber can be as high as 3500K. Thus, effective cooling of the thrust chamber becomes an essential criterion while designing a rocket engine. Objective: A new cooling method of thrust chambers was introduced by Chiaverni, which is termed as Vortex Combustion Cold-Wall Chamber (VCCW). The patent works on cyclone separators and confined vortex flow mechanism for providing high propellant mixing with improved degree of turbulence inside the combustion chamber, providing the required notion for studies on VCCW. The flow inside a VCCW has a complex structure characterised by axial pressure losses, swirl velocities, centrifugal force, flow reversal and strong turbulence. In order to study the flow phenomenon, both the experimental and numerical investigations are carried out. Methods: In this study, non-reactive flow analysis was conducted with real propellants like gaseous oxygen and hydrogen. The test was conducted to analyse the influence of mixture ratio and injection pressure of the propellants on the chamber pressure in a vortex combustion chamber. A vortex combustor was designed in which the oxidiser injected tangentially at the aft end near the nozzle spiraled up to the top plate and formed an inner core inside the chamber. The fuel was injected radially from injectors provided near the top plate and the propellants were mixed in the inner core. This resulted in enhanced mixing and increased residence time for the fuel. More information on the flow behaviour has been obtained by numerical analysis in Fluent. The test also investigated the sensitivity of the tangential injection pressure on the chamber pressure development. Results: All the test cases showed an increase in chamber pressure with the mixture ratio and injection pressure of the propellants. The maximum chamber pressure was found to be 3.8 bar at PC1 and 2.7 bar at PC2 when oxidiser to fuel ratio was 6.87. There was a reduction in chamber pressure of 1.1 bar and 0.7 bar at PC1 and PC2, respectively, in both the cases when hydrogen was injected. A small variation in the pressure of the propellant injected tangentially made a pronounced effect on the chamber pressure and hence vortex combustion chamber was found to be very sensitive to the tangential injection pressure. Conclusion: VCCW mechanism has been to be found to be very effective for keeping the chamber surface within the permissible limit and also reducing the payload of the space vehicle.
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Hayes, Daniel. "Reverberant Chamber Enhancement." Journal of the IEST 58, no. 1 (November 1, 2015): 24–36. http://dx.doi.org/10.17764/1098-4321.58.1.24.
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Typical reverberant chambers used for High Intensity Acoustic Testing (HIAT) can achieve high sound pressure levels (SPL) across most of the applicable frequency range (20 Hz to 10 kHz), but they have limitations. Depending on the size of the chamber, low frequency chamber modes may be limited in the testing frequency range. In addition, reverberant chambers that use conventional 1/3-Octave controllers are not able to control low frequency chamber modes as effectively as the higher frequencies. A typical response to this inability to control the chamber modes is to high pass the frequency range of the excitation in the chamber to prevent exciting the low frequency modes. This method protects the test article from over-testing, although it also might under-test an article that has a fundamental mode below the high-pass frequency of the chamber. Recently, Maryland Sound International conducted a test at the Naval Research Laboratory (NRL) to determine if Direct Field Acoustic Testing (DFAT) technology could be applied to conventional reverberant chambers.
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Arumugam, Sozhi, Pitchandi Kasivisvanathan, M. Arventh, and P. Maheshkumar. "Effect of Re-Entrant and Toroidal Combustion Chambers in a DICI Engine." Applied Mechanics and Materials 787 (August 2015): 722–26. http://dx.doi.org/10.4028/www.scientific.net/amm.787.722.
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This paper presents the experimental work to investigate the effect of Re-entrant and Toroidal combustion chambers in a DICI Engine. The two combustion chambers namely Re-entrant combustion chamber (RCC) and Toroidal combustion chamber (TCC) were fitted in a 4.4 kW single cylinder Direct Injection Compression Ignition (DICI) engine and tests were conducted with diesel. The influences of the combustion chamber geometry characteristics on combustion, performance and emissions characteristics have been investigated. This investigation shows the peak pressure of re-entrant chamber is higher than that of toroidal chamber. The heat release rate and brake thermal efficiency for re-entrant chamber are slightly higher than that of toroidal chamber. Specific fuel consumption is lower for toroidal chamber than that of re-entrant chamber. The enhancement in reduction of carbon monoxide, hydrocarbon is observed for Re-entrant chamber compared to the Toroidal chamber. Oxides of nitrogen are reduced for toroidal chamber than that of re-entrant chamber.
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Banis, Kārlis. "The Effect of separated Expansion Chamber Parameters on Exhaust Pressure Oscillations in Single Cylinder Motorcycle Engine." Rural Sustainability Research 43, no. 338 (August 1, 2020): 42–51. http://dx.doi.org/10.2478/plua-2020-0006.
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AbstractThis paper investigates the effect of separated exhaust expansion chamber parameters on pressure oscillations in spark-ignited internal combustion (IC) gasoline engines. It is known that exhaust expansion chambers are becoming increasingly more popular among both – original equipment (OE) and aftermarket equipment (AE) exhaust system manufacturers for performance-oriented motorcycles equipped with mainly single cylinder engines, but the companies are reluctant to reveal any detailed principles of operation of the mentioned expansion chambers. The subject of this research is the type of expansion chamber (separate) as used on performance-oriented motorcycles, particularly its’ effect on exhaust pressure pulsations as different chamber volumes, locations and passage sizes are tested. Time-dependent computational fluid dynamics (CFD) analysis was carried out in Solidworks Flow Simulation environment on a simplified exhaust header pipe model imitating engine operation at full load and steady speed. Honda CRF450R motorcycle engine was used as the example and fully defined using a 1D engine performance calculator software to determine the combustion chamber pressure and exhaust valve lift at any given crankshaft position. Volume flow rate of exhaust gasses at the header pipe inlet was calculated based on engine parameters and operating speed. The average pressure values with respect to physical time were measured and graphed across the header pipe inlet cross-section. Eight different header pipe and exhaust expansion chamber combinations were modelled, tested, and results compared at low, medium and high engine speeds. It was found that the presence of exhaust expansion chamber tends to dampen the amplitude and decrease the frequency of pressure oscillations generated at the opening of the exhaust valve(s). Observations show that the addition of an expansion chamber as per design of performance-oriented motorcycles helps to decrease the negative effect of engine tuning while also dampening the positive effect.
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Lambeth, Christopher, Benjamin Kolevski, Terence Amis, and Kristina Kairaitis. "Feedback modulation of surrounding pressure determines the onset of negative effort dependence in a collapsible tube bench model of the pharyngeal airway." Journal of Applied Physiology 123, no. 5 (November 1, 2017): 1118–25. http://dx.doi.org/10.1152/japplphysiol.00378.2017.
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Negative effort dependence (NED), decreased airflow despite increased driving pressure, has been proposed as a specific obstructive sleep apnea (OSA) phenotypic characteristic. We examined conditions under which NED occurs in a collapsible tube, pharyngeal airway bench model with the chamber enclosed, focusing on relationships with surrounding pressure levels and longitudinal strain. Using a vacuum source, graded airflows (V̇; 0–5 l/s) were generated through a thin-walled latex tube enclosed within a rigid, cylindrical chamber, sealed with initial chamber pressures (Pci) of 0–5 cmH2O (separate runs), or opened to the atmosphere. Upstream minus downstream pressure (Pu − Pd), maximum airflow (V̇max), and chamber pressure (Pc) were measured at 0–50% longitudinal strain. NED occurred across the range of Pci and strains studied but was most pronounced for the chamber open condition. With a sealed chamber, V̇ increased and Pc decreased with increasing Pu − Pd until the onset of NED at V̇max and a Pc value that was designated as critical (Pcc). Pcc was lowest (−17 cmH20) and V̇max was highest (~5 l/s) with chamber sealed: Pci = 0 cmH2O and 12.5 to 25% strain. We conclude that for our collapsible tube model, the achievable V̇max before the onset of NED depends on both the initial conditions (Pci and strain) and the dynamics of feedback between driving pressure and chamber pressure (chamber sealed vs. open). NED-based phenotypic analyses for OSA may need to focus on potential feedback control mechanisms (eg lung volume change, muscle activity) that may link peripharyngeal tissue pressure levels to driving pressures for airflow. NEW & NOTEWORTHY A collapsible tube, pharyngeal airway bench model was used to study the role of surrounding pressure and longitudinal wall strain at the onset of negative effort dependence (NED). NED occurred to varying degrees across all conditions tested, but maximum airflow was achieved with 1) low initial surrounding pressure, 2) a feedback mechanism between surrounding pressure and driving pressure; and 3) a moderate amount of strain applied. Potential impacts on OSA phenotypic analyses are discussed.
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Pawitan, Krisna Adi, Ben Gossling, William Allsop, and Tom Bruce. "VIOLENT IN-CHAMBER LOADS IN AN OSCILLATING WATER COLUMN CAISSON." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 11. http://dx.doi.org/10.9753/icce.v36.structures.11.
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In 2009, four of 16 chambers in the Mutriku breakwater-integrated Oscillating Water Column (OWC) were badly damaged by storms, probably due to breaking wave loads, and slam within the chamber. To minimize exposure of future plant to such risks, it is necessary to characterise wave conditions under which such an installation could experience impact loads. This characterisation can be crucial to controling the power-take off resistance to increase the survability of the device during extreme weather. Large scale physical model tests in the Grosse Wellenkanal (GWK) included a video camera installed inside the chamber facing the rear chamber wall. Pressure sensors in the ceiling of the chamber were utilised to quantify the water loads. In-chamber impact pressures of up to 8 ÏgH were recorded on the chamber ceiling, associated with the ‘sloshing’ observed. The “sloshing†phenomenon is not uncommon and should be considered in design processes.
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WELCH, D. R., D. V. ROSE, W. M. SHARP, C. L. OLSON, and S. S. YU. "Effects of preneutralization on heavy ion fusion chamber transport." Laser and Particle Beams 20, no. 4 (October 2002): 621–25. http://dx.doi.org/10.1017/s0263034602204279.
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Beams for heavy ion fusion are likely to require at least partial neutralization in the reactor chamber. Present target designs call for higher beam currents and smaller focal spots than most earlier designs, leading to high space-charge fields. Focusing is complicated by beam stripping in the low-pressure background gas expected in chambers. One method proposed for neutralization is passing an ion beam through a plasma before the beam enters the chamber. In this article, the electromagnetic particle-in-cell code LSP is used to study the effectiveness of this form of preneutralization for a range of plasma and beam parameters. For target chamber pressures below a few milliTorr of flibe gas, preneutralization is found to significantly reduce the beam emittance growth and spot size in the chamber.
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Du, Mei, Zou, Jiang, and Xie. "Conjugate Heat Transfer Investigation on Swirl-Film Cooling at the Leading Edge of a Gas Turbine Vane." Entropy 21, no. 10 (October 15, 2019): 1007. http://dx.doi.org/10.3390/e21101007.
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Numerical calculation of conjugate heat transfer was carried out to study the effect of combined film and swirl cooling at the leading edge of a gas turbine vane with a cooling chamber inside. Two cooling chambers (C1 and C2 cases) were specially designed to generate swirl in the chamber, which could enhance overall cooling effectiveness at the leading edge. A simple cooling chamber (C0 case) was designed as a baseline. The effects of different cooling chambers were studied. Compared with the C0 case, the cooling chamber in the C1 case consists of a front cavity and a back cavity and two cavities are connected by a passage on the pressure side to improve the overall cooling effectiveness of the vane. The area-averaged overall cooling effectiveness of the leading edge () was improved by approximately 57%. Based on the C1 case, the passage along the vane was divided into nine segments in the C2 case to enhance the cooling effectiveness at the leading edge, and was enhanced by 75% compared with that in the C0 case. Additionally, the cooling efficiency on the pressure side was improved significantly by using swirl-cooling chambers. Pressure loss in the C2 and C1 cases was larger than that in the C0 case.
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Nesterenkov, V. M., L. A. Kravchuk, Yu A. Arkhangelsky, I. A. Petrik, and Yu A. Marchenko. "Electron beam welding of medium-pressure chamber of gas turbine engine." Paton Welding Journal 2015, no. 12 (December 28, 2015): 29–33. http://dx.doi.org/10.15407/tpwj2015.12.06.
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Segall, Paul. "Magma chambers: what we can, and cannot, learn from volcano geodesy." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2139 (January 7, 2019): 20180158. http://dx.doi.org/10.1098/rsta.2018.0158.
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Geodetic observations on volcanoes can reveal important aspects of crustal magma chambers. The rate of decay of deformation with distance reflects the centroid depth of the chamber. The amplitude of the deformation is proportional to the product of the pressure change and volume of the reservoir. The ratio of horizontal to vertical displacement is sensitive to chamber shape: sills are efficient at generating vertical displacement, while stocks produce more horizontal deformation. Geodesy alone cannot constrain important parameters such as chamber volume or pressure; furthermore, kinematic models have no predictive power. Elastic response combined with influx proportional to pressure gradient predicts an exponentially decaying flux, leading to saw-tooth inflation cycles observed at some volcanoes. Yet many magmatic systems exhibit more complex temporal behaviour. Wall rock adjacent to magma reservoirs cannot behave fully elastically. Modern conceptual models of magma chambers also include cumulate and/or mush zones, with potentially multi-level melt lenses. A viscoelastic shell surrounding a spherical magma chamber significantly modifies the predicted time-dependent response; post-eruptive inflation can occur without recharge if the magma is sufficiently incompressible relative to the surrounding crust (Segall P. 2016 J. Geophys. Res. Solid Earth , 121 , 8501–8522). Numerical calculations confirm this behaviour for both oblate and prolate ellipsoidal chambers surrounded by viscoelastic aureoles. Interestingly, the response to a nearly instantaneous pressure drop during an explosive eruption can be non-monotonic as the rock around the chamber relaxes at different rates. Pressure-dependent recharge of a non-Newtonian magma in an elastic crust leads to an initially high rate of inflation which slows over time; behaviour that has been observed in some magmatic systems. I close by discussing future challenges in volcano geodesy. This article is part of the Theo Murphy meeting issue ‘Magma reservoir architecture and dynamics’.
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Cha, H. J., D. Saez de Jauregui, A. Grau, and A. S. Müller. "Beam-induced electron multipacting with mode resonance in a vacuum chamber." Journal of Instrumentation 16, no. 11 (November 1, 2021): P11001. http://dx.doi.org/10.1088/1748-0221/16/11/p11001.
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Abstract Some vacuum chambers in particle accelerators perform a waveguide- or resonator-like behavior due to their unique geometries. Electron multipacting caused by such a structural property might be able to overwhelm the classical beam-induced multipacting. This article shows that the wakefields of particle beams could stimulate the resonant modes of a vacuum chamber with a near-rectangular waveguide shape and accordingly induce much stronger electron avalanche in the chamber. Especially, it has been believed that the multipacting is responsible for pressure rise in a vacuum chamber, where energetic secondary electrons with growing numbers collide with gas particles at the chamber wall. Based on numerical simulations, the electron multipacting mechanism with the mode resonance is proposed, which can explain the significant pressure variation measured in our cryogenic vacuum chamber.
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Itoh, S., S. Kubota, S. Nagano, and M. Fujita. "On Generation of Ultra-High Pressure by Converging of Underwater Shock Waves." Journal of Pressure Vessel Technology 120, no. 1 (February 1, 1998): 51–55. http://dx.doi.org/10.1115/1.2841884.
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The characteristics of a new assembly for the shock consolidation of difficult-to-consolidate powders, such as inter-metallic compounds or ceramic materials, were investigated by both the experimental method and numerical simulation method. The assembly consists of an explosive container, a water chamber, and a powder container. Once the explosive is detonated, a detonation wave occurs and propagates, and then impinges on the water surface of the water chamber. After that, there occurs immediately an underwater shock wave in the water chamber. The underwater shock wave interacts with the wall of the chamber during its propagation so that its strength is increased by the converging effect. We used the usual shadow graph system to photograph the interaction process between detonation wave and water. We also used a Manganin piezoresistance gage to measure the converged pressure of the conical water chamber. Finally, we numerically investigated, in detail, the converging effects of the various conical water chambers on the underwater shock waves. The experimental results and the correspondingly numerical results agree quite well with each other.
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Slama, Vaclav, David Simurda, and Richard Lenhard. "Pressure Losses Downstream of a Compact Valve in the Inlet Chamber of an Intermediate-Pressure Steam Turbine." Energies 15, no. 22 (November 21, 2022): 8753. http://dx.doi.org/10.3390/en15228753.
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Deep knowledge about pressure and energy losses in each part of a steam turbine is crucial for assuring the required efficiency and operational reliability. This paper presents the experimental as well as the numerical study of pressure losses in the inlet chamber of an intermediate-pressure steam turbine. Measurements were carried out on a complex model, where not only was there an inlet turbine chamber, but also a compact valve assembly situated upstream and nozzles situated downstream. The compact valve as well as the turbine inlet chamber were relatively small. Therefore, greater pressure losses were expected. The aerodynamic laboratory of the Institute of Thermomechanics of the Czech Academy of Sciences was responsible for acquiring the measurements, which were carried out in a modular in-draft wind tunnel. In order to learn further details, numerical simulations were carried out. Doosan Skoda Power was responsible for this. A package of ANSYS software tools was used. Measured data were described and compared with numerical ones. Pressure losses were generalized in the form of the total pressure loss coefficient. As a result, pressure losses in similar turbine compact inlet chambers can be predicted with the required accuracy.
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Ling, Xue Qin, Peng Fu, Wei Zhang, and Yang Chen. "Mechanical Strength Analysis and Structure Improvement of Diaphragm Chamber Based on Finite Element Method." Advanced Materials Research 690-693 (May 2013): 1945–49. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.1945.
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Diaphragm chamber is the key component in fluid end of high pressure diaphragm pump for long distance pipeline transportation. Structural dimensions are the major factors affecting mechanical strength and manufacturing cost of diaphragm chamber. In this paper, diaphragm chamber was simulated by finite element analysis software ANSYS. Mechanical strength of diaphragm chamber was checked in the light of ASMEVIII-2. The structure of diaphragm chamber was modified for the purpose of extending service life and reducing production costs. The analysis results provide some theoretical guidance for research and development of diaphragm chambers and relevant products.
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Rahim, F., M. Elia, M. Ulinski, and M. Metghalchi. "Burning velocity measurements of methane-oxygen-argon mixtures and an application to extend methane-air burning velocity measurements." International Journal of Engine Research 3, no. 2 (April 1, 2002): 81–92. http://dx.doi.org/10.1243/14680870260127873.
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Burning velocities of methane-oxygen-argon mixtures have been measured in two matched constant-volume chambers, one spherical and one cylindrical. Burning velocities in the spherical chamber were determined from the pressure rise using a thermodynamic model based on the conservation of mass and energy. Photographic observations made through end windows in the cylindrical chamber at early times were used to study the effects of flame curvature and stretch on the flame speed under constant pressure conditions. The cylindrical chamber was also used to investigate flame shape, cracking and wrinkling. Substitution of argon for the nitrogen in air increased the range of pressure and temperature at which measurements could be made. A correlation for the burning velocity of methane-oxygen-argon mixtures has been developed for the range of pressures from 1 to 40 atmospheres, unburned gas temperatures from 298 to 650 K and fuel-air equivalence ratios from 0.8 to 1.2. Using this correlation and previous results for methane-air mixtures, the burning velocities of methane-air mixtures have been extended to higher temperatures. The results are compared to other experimental measurements and theoretical predictions.
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Tian, Zifeng, Jianfeng Lu, Zhao Gu, Lihua Yu, Hao Zhou, and Lijun Yang. "Theoretical and Experimental Study on Rapid Decompression Oscillation in Altitude Chamber." International Journal of Aerospace Engineering 2022 (November 18, 2022): 1–16. http://dx.doi.org/10.1155/2022/9258503.
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Given the frequent airflow excitation phenomenon caused by the rapid decompression of the altitude chamber, the mathematical model of the nonlinear system of the rapid decompression of the altitude chamber is established. The polynomial parameter method is used to evaluate the characteristics of airflow oscillation, and a rapid decompression test system is built. The test results verify the pressure oscillation phenomenon of the numerical simulation. This paper proves the phenomenon of fluid-induced vibration in the process of rapid decompression and determines that the main factors affecting the induced oscillation are the diameter of the pipe (throat), pressure difference between the two chambers, and initial pressure conditions. Specifically, this study establishes safety and reliability for preventing engineering accidents caused by resonance in the altitude chamber.
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Bobrovnitchii, G. S., Ana Lúcia Diegues Skury, and S. N. Monteiro. "Novel High Pressure Multi-Anvil Device for Diamond Production." Materials Science Forum 727-728 (August 2012): 1369–74. http://dx.doi.org/10.4028/www.scientific.net/msf.727-728.1369.
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The synthesis of diamond crystal from powder mixture of graphite and catalyst alloy is a well known process but it is limited to relatively small crystal dimensions due to the size of the conventional compression chambers. In this work the design and construction of a novel high pressure multi-anvil device with a parallelepiped shaped compression chamber is presented. The design allows the length of the chamber to be limited only by the working space of the press equipment. A four horizontal anvils device was constructed for a specific 2500 ton press with a 600mm working space. The efficiency of this construction was tested in diamond crystal synthesis.
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Jawarneh, Ali M., P. Sakaris, and Georgios H. Vatistas. "Experimental and Analytical Study of the Pressure Drop Across a Double-Outlet Vortex Chamber." Journal of Fluids Engineering 129, no. 1 (June 8, 2006): 100–105. http://dx.doi.org/10.1115/1.2375131.
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This paper presents experimental and analytical results concerning the pressure drop and the core size in vortex chambers. The new formulation is based on the conservation of mass and energy integral equations and takes into account the presence of two outlet ports. The diminishing vortex strength is introduced through the vortex decay factor. The influence of vortex chamber geometry, such as diameter ratio, aspect ratio, and Reynolds number, on the flow field have been examined and compared with the present experimental data. It is shown that the presence of the swirl velocity component makes the pressure drop across a vortex chamber significantly different than the familiar unidirectional pipe flow. When the chamber length is increased, the vortex diminishes under the action of friction, producing a weaker centrifugal force which leads to a further pressure drop. It is revealed that by increasing the Reynolds number, the cores expand resulting into a larger pressure coefficient. For a double-outlet chamber where the flow is divided into two streams, the last parameter is found to be less than that of a single-outlet.
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Vásquez, R. A., and F. S. Costa. "SPRAY CONE ANGLES GENERATED BY A DUAL CENTRIFUGAL INJECTOR." Revista de Engenharia Térmica 13, no. 1 (June 30, 2014): 36. http://dx.doi.org/10.5380/reterm.v13i1.62067.
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A dual pressure swirl injector is characterized by two independent concentric chambers which can provide independent rotational levels to a single liquid or two different liquids. This paper compares theoretical, semi-empirical and experimental results concerning the spray cone angles formed by injection of water, ethanol and biodiesel through a dual pressure swirl injector. Data are obtained for injection of the same liquid through the primary and secondary chambers and for injection of ethanol in the primary chamber and biodiesel through the secondary chamber of the injector. Experimental data are obtained using photographic techniques and are analyzed by an image processing software developed in Matlab language.
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Šabacká, Pavla, Jiří Maxa, Robert Bayer, Petr Vyroubal, and Tomáš Binar. "Slip Flow Analysis in an Experimental Chamber Simulating Differential Pumping in an Environmental Scanning Electron Microscope." Sensors 22, no. 23 (November 22, 2022): 9033. http://dx.doi.org/10.3390/s22239033.
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This paper describes the combination of experimental measurements with mathematical–physical analysis during the investigation of flow in an aperture at low pressures in a prepared experimental chamber. In the first step, experimental measurements of the pressure in the specimen chamber and at its outlet were taken during the pumping of the chamber. This process converted the atmospheric pressure into the operating pressure typical for the current AQUASEM II environmental electron microscope at the ISI of the CAS in Brno. Based on these results, a mathematical–physical model was tuned in the Ansys Fluent system and subsequently used for mathematical–physical analysis in a slip flow regime on a nozzle wall at low pressure. These analyses will be used to fine-tune the experimental chamber. Once the chamber is operational, it will be possible to compare the results obtained from the experimental measurements of the nozzle wall pressure, static pressure, total pressure and temperature from the nozzle axis region in supersonic flow with the results obtained from the mathematical–physical analyses. Based on the above comparative analyses, we will be able to determine the realistic slip flow at the nozzle wall under different conditions at the continuum mechanics boundary.