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Статті в журналах з теми "Conical gap"
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KRESTIN, Evgeny A., and Grigoriy V. SEREBRYAKOV. "HYDRODYNAMIC CALCULATION OF CONTACTLESS SEALS WITH PLANE SLOTS IN DRIVES OF ELECTRIC POWER SYSTEMS." Urban construction and architecture 11, no. 2 (December 15, 2021): 171–77. http://dx.doi.org/10.17673/vestnik.2021.02.22.
Повний текст джерелаАнотація:
Non-contact seals with fl at slott ed gaps of drives of electric power systems used in switchgears of hydraulic units, as well as in pumps and hydraulic motors have been investigated. Calculation of seals based on average clearance results in an underestimation or overestimation of the leakage rate compared to the operational values. The regularity of the distribution of pressure and fl ow rate in the gap of a fl at conical slot is determined, and formulas for the fl ow rate (leakage) and friction forces acting on the walls of the conical slot are found. To solve the problem, the approximate Navier-Stokes and fl ow continuity equations are used. Several special cases of the fl ow of the working fl uid in diff erent gaps are considered: a plane-parallel gap with an oscillating wall and at a constant pressure gradient and a conical gap at diff erent ratios of the pressure drop and the frictional action of the moving channel wall. When the wall oscillates in a conical gap and constant pressure, the presence of an extremum is characteristic. In this case, an excess pressure appeared in the slott ed gap, creating a supporting force, and the pressure value became high enough. When the lower wall of the conical slot moves in the direction of the increasing gap, the pressure inside the slott ed channel, under certain conditions, can reach a complete vacuum, the value of which is limited by the bulk strength of the liquid and the pressure of saturated vapor at a given temperature. When the pressure drop and oscillations of the wall of the conical gap are additive, then at a suffi ciently high velocity of the wall movement, the pressure inside the slot can even increase and exceed the value of the supplied pressure.
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Koprowski, Mariusz. "An analysis of lubricating medium flow through unsymmetrical lubricating gap of conical slide bearing." Polish Maritime Research 14, no. 4 (October 1, 2007): 59–63. http://dx.doi.org/10.2478/v10012-007-0041-x.
Повний текст джерелаАнотація:
An analysis of lubricating medium flow through unsymmetrical lubricating gap of conical slide bearing This paper presents a computer analysis of lubricating medium flow through unsymmetrical lubricating gap of conical slide bearing. Numerical calculations were carried out with the use of the software Matlab 7.1 and Mathematica 5.2 for example conical slide bearings of different values of cone apex angles of pin and sleeve and set values of relative eccentricity and skewing angle as well as dimensionless bearing length equal to 1.
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Sinha, P., P. Chandra, and S. Bhartiya. "Analysis of a non-constant gap externally pressurized conical bearing with temperature and pressure dependent viscosity." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 214, no. 5 (May 1, 2000): 699–710. http://dx.doi.org/10.1243/0954406001523704.
Повний текст джерелаАнотація:
The present paper analyses an externally pressurized non-constant gap conical bearing rotating with a uniform angular velocity. The lubricant is assumed to be incompressible and its viscosity varies with both pressure and temperature. Although the inertia effect due to lubricant flow has been neglected, rotational inertia is taken into account. The governing system of coupled momentum and energy equations, in conical coordinates, is solved numerically using the finite difference method, to determine various bearing characteristics. The effect of the viscosity-pressure exponent, , on various characteristics of the bearing has been studied. It is seen that variation of does not produce any significant change in the load capacity for convergent and constant gap conical bearings. For the divergent gap also, no significant difference is seen when the gap is slightly divergent. However, for highly divergent gaps, the load capacity increases with an increase in . It is also seen that variation in does not produce any significant change in torque of the bearing.
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Wang, J. M., and P. H. J. Schellekens. "Tri-Conical Gap-Shaped Externally Pressurized Gas Bearing Pads." Tribology Transactions 37, no. 4 (January 1994): 850–56. http://dx.doi.org/10.1080/10402009408983368.
Повний текст джерела
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KORNEYEV, А. Yu, A. V. SYTIN, А. V. KUZAVKA, and E. V. MISHCHENKO. "THE MATHEMATICAL MODEL OF CALCULATION OF THE THRUST CONICAL FOIL BEARINGS." Fundamental and Applied Problems of Engineering and Technology 3 (2020): 3–10. http://dx.doi.org/10.33979/2073-7408-2020-341-3-3-10.
Повний текст джерелаАнотація:
The question of creating a unified method of calculation for the thrust and conical part of the combined thrust conical foil bearings. Mathematical model for calculating the turbulent flow of a lubricant in the conical and thrust parts of foil bearings. The design of the bearing and foil, the function of the gap in the lubricant layer of the bearing, the Reynolds equation and the equation of deformations of elastic elements are presented.
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Kalita, W., N. Yegani, Cz M. Rodkiewicz, and J. S. Kennedy. "On the Laminar Flow Characteristics of Conical Bearings. Part II—Experimental Verification." Journal of Tribology 108, no. 1 (January 1, 1986): 59–64. http://dx.doi.org/10.1115/1.3261144.
Повний текст джерелаАнотація:
The laminar flow characteristics of the externally pressurized central recess conical bearings with narrow gaps, predicted theoretically in Part I of this paper, have been verified experimentally. Two main effects on the performance of conical bearings have been investigated, namely: the effect of nonconstant film thickness along the gap of the bearing and the effect of rotation. It was found that experimental pressure distributions and load capacity of the constant and divergent gap bearings were in close agreement with the theoretical data for the low rotational velocities however, with the increased rotation, the experimental values were higher than theoretically predicted. The experimental values of pressure, load capacity, and the torque of convergent gap bearings were found higher than theoretical.
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Chen, Chi Feng, Yu Cheng Cheng, and Chia Jen Ting. "Improved Antireflection Property of Subwavelength Structures Based on Finite Difference Time Domain Method." Applied Mechanics and Materials 364 (August 2013): 780–84. http://dx.doi.org/10.4028/www.scientific.net/amm.364.780.
Повний текст джерелаАнотація:
A kind of subwavelength structure array is numerically investigated to improved antireflection property. Based on finite difference time domain method, we consider adding a small conical structure in the gap between the pure periodic conical subwavelength structure to analylz the antireflection property in spectral range of 400-1100 nm. The improved antireflection property of subwavelength structures have distinguishing characteristic in particular places. The result shows the morphological effect on reflectance of new conical shape subwavelength structures.
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Chen, Chi-Feng, Yu-Cheng Cheng, and Chia-Jen Ting. "Improved Antireflection Properties of an Optical Film Surface with Mixing Conical Subwavelength Structures." Journal of Nanomaterials 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/459325.
Повний текст джерелаАнотація:
Based on finite difference time domain method, an optical film surface with mixing conical subwavelength structures is numerically investigated to improve antireflection property. The mixing conical subwavelength structure is combined with the pure periodic conical subwavelength structures and the added small conical structures in the gap between the pure periodic conical subwavelength structures. The antireflection properties of two types of subwavelength structures with different aspect ratios in spectral range of 400–800 nm are analyzed and compared. It is shown that, for the mixing type, the average reflectance is decreased and the variances of the reflectance are evidently smaller. When the added structure with a better aspect ratio exists, the average reflectance of the surface can be below 0.30%. Obviously, the antireflection properties of the optical film surface with mixing conical subwavelength structures can be improved.
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Saxena, Snigdha, Peeyush Chandra, and Prawal Sinha. "THD Analysis of Non-Constant Gap, Externally Pressurized Conical Bearings." Tribology Transactions 38, no. 2 (January 1995): 438–44. http://dx.doi.org/10.1080/10402009508983426.
Повний текст джерела
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Oh, Dong Hyeon, and Gil Ho Yoon. "A Study of Longitudinal Waveguide with Band Gap Using Cylindrical and Conical Shape Periodic Structure." Applied Sciences 11, no. 16 (August 6, 2021): 7257. http://dx.doi.org/10.3390/app11167257.
Повний текст джерелаАнотація:
This research presents the theoretical and experimental studies for cylindrical and conical periodic structures to control longitudinal wave motion. Many relevant researches exist to stop and pass a certain frequency wave without active devices with periodic structures called metamaterials. To modify or control longitudinal wave propagation, i.e., passing or blocking mechanical wave within specific frequency ranges, repeated mass-spring systems or metamaterials can be applied. By integrating a few identical structural components to form a whole structure, it is possible to make a mechanical filter for wave propagation. Most studies rely on straight bar with cylindrical structure. Thus, with a unit cell that have a cylindrical and conical structure, this research presents the extensions toward the studies of the wave motions for straight and curved bars with finite element simulations and experiment studies. The results show that the hybrid cylindrical and conical periodic structures can be effective in terms of wave motion control and stiffness.
Дисертації з теми "Conical gap"
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Zuniga, Humberto. "STUDY OF FILM COOLING EFFECTIVENESS: CONICAL, TRENCHED AND ASYMMETRICAL SHAPED HOLES." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2239.
Повний текст джерелаАнотація:
Film cooling is a technique whereby air from the compressor stage of a gas turbine engine is diverted for cooling purposes to parts, such as the turbine stage, that operate at very high temperatures. Cooling arrangements include impingement jets, finned, ribbed and turbulated channels, and rows of film cooling holes, all of which over the years have become progressively more complex. This costly, but necessary complexity is a result of the industry's push to run engines at increasingly higher turbine inlet temperatures. Higher temperatures mean higher efficiency, but they also mean that the turbine first stage operates hundreds of degrees Kelvin above the melting point of the metal core of the vanes and blades. Existing cooling technology and materials make it possible to protect these parts and allow them to function for extended periods of time--but this comes at a price: the compressed air that is used for cooling represents a considerable penalty in overall turbine efficiency. The aim of current cooling research is threefold: to improve the protection of components from extreme fluxes in order to extend the life of the parts; to increase the inlet turbine operating temperature; and to reduce the amount of air that is diverted from the compressor for cooling. Current film cooling schemes consist of forcing air through carefully machined holes on a part and ejecting it at an angle with the intent of cooling that part by blanketing the surface downstream of the point of ejection. The last major development in the field has been the use of expanded hole exits, which reduce coolant momentum and allow for greater surface coverage. Researchers and designers are continuously looking for novel geometries and arrangements that would increase the level of protection or maintain it while using less coolant.
It was found that the performance of fan-shaped holes inside trenches is actually diminished by the presence of the trench. It is obvious, since the fan diffuses the flow, reducing the momentum of the coolant; the addition of the trench further slows the flow down. This, in turn, leads to the quicker ingestion of the main flow by the jets resulting in lower effectiveness. The next part of the study consisted of systematically increasing the depth of the trench for the fan-shaped holes. The purpose of this was to quantify the effect of the trench on the film cooling effectiveness. It was found that the presence of the trench significantly reduces the film effectiveness, especially for the deeper cases. At the higher blowing ratios, the overall performance of the fans collapses to the same value signifying insensitivity to the blowing ratio. A recent study suggests that having a compound angle could reduce the protective effect of the film due to the elevated interaction between the non-co-flowing coolant jet and the mainstream. Although it has been suggested that a non-symmetric lateral diffusion could mitigate the ill effects of having a compound angle, little has been understood on the effect this non-symmetry has on film cooling effectiveness. The last part of this study investigates the effect of non-symmetric lateral diffusion on film cooling effectiveness by systematically varying one side of a fan-shaped hole. For this part of the study, one of the lateral angles of diffusion of a fan-shaped hole was changed from 5° to 13°, while the other side was kept at 7°. It was found that a lower angle of diffusion hurts performance, while a larger diffusion angle improves it. However, the more significant result was that the jet seemed to be slightly turning. This dissertation investigates such novel methods which one day may include combinations of cylindrical and fan-shaped holes embedded inside trenches, conical holes, or even rows of asymmetric fan-shaped holes. The review of current literature reveals that very few investigations have been done on film cooling effectiveness for uniformly diffusing conical holes. They have been treated as a sort of side novelty since industrial partners often say they are hard to manufacture. To extend our understanding of effectiveness of conical holes, the present study investigates the effect of increasing diffusion angle, as well as the effect of adding a cylindrical entrance length to a conical hole. The measurements were made in the form of film cooling effectiveness and the technique used was temperature sensitive paint. Eight different conical geometries were tested in the form of coupons with rows of holes. The geometry of the holes changed from pure cylindrical holes, a 0° cylindrical baseline, to an 8° pure cone. The coupons were tested in a closed loop wind tunnel at blowing ratios varying from 0.5 to 1.5, and the coolant employed was nitrogen gas. Results indicate that the larger conical holes do, in fact offer appropriate protection and that the holes with the higher expansion angles perform similar to fan-shaped baseline holes, even at the higher blower ratios. The study was also extended to two other plates in which the conical hole was preceded by a cylindrical entry length. The performance of the conical holes improves as a result of the entry length and this is seen at the higher blowing ratios in the form of a delay in the onset of jet detachment. The results of this study show that conical expanding holes are a viable geometry and that their manufacturing can be made easier with a cylindrical entry length, at the same time improving the performance of these holes.
This suggests that the jets actually have two regions: one region with reduced momentum, ideal for protecting a large area downstream of the point of injection; and another region with more integrity which could withstand more aggressive main flow conditions. A further study should be conducted for this geometry at compound angles with the main flow to test this theory. The studies conducted show that the temperature sensitive paint technique can be used to study the performance of film cooling holes for various geometries. The studies also show the film cooling performance of novel geometries and explain why, in some cases, such new arrangements are desirable, and in others, how they can hurt performance. The studies also point in the direction of further investigations in order to advance cooling technology to more effective applications and reduced coolant consumption, the main goal of applied turbine cooling research.
Trench cooling consists of having film cooling holes embedded inside a gap, commonly called a trench. The walls of this gap are commonly vertical with respect to the direction of the main flow and are directly in the path of the coolant. The coolant hits the downstream trench wall which forces it to spread laterally, resulting in more even film coverage downstream than that of regular holes flush with the surface. Recent literature has focused on the effect that trenching has on cylindrical cooling holes only. While the results indicate that trenches are an exciting, promising new geometry derived from the refurbishing process of thermal barrier ceramic coatings, not all the parameters affecting film cooling have been investigated relating to trenched holes. For example, nothing has been said about how far apart holes inside the trench will need to be placed for them to stop interacting. Nothing has been said about shaped holes inside a trench, either. This dissertation explores the extent to which trenching is useful by expanding the PI/D from 4 to 12 for rows of round and fan holes. In addition the effect that trenching has on fan-shaped holes is studied by systematically increasing the trench depth. Values of local, laterally-averaged and spatially-averaged film cooling effectiveness are reported. It is found that placing the cylinders inside the trench and doubling the distance between the holes provides better performance than the cylindrical, non-trenched baseline, especially at the higher blowing ratios, M [greater than] 1.0. At these higher coolant flow rates, the regular cylindrical jets show detachment, while those in the trench do not. They, in fact perform very well. The importance of this finding implies that the number of holes, and coolant, can be cut in half while still improving performance over regular holes. The trenched cylindrical holes did not, however, perform like the fan shaped holes.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering PhD
2
Wang, Zhiguo. "Experimental studies and CFD simulations of conical spouted bed hydrodynamics." Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/61.
Повний текст джерелаАнотація:
Conical spouted beds have been commonly used for drying suspensions, solutions and pasty materials. They can also be utilized in many other processes, such as catalytic partial oxidation of methane to synthesis gas, coating of tablets, coal gasification and liquefaction, pyrolysis of sawdust or mixtures of wood residues.
The main objectives of this work include both the experimental research and mathematical modelling of the conical spouted bed hydrodynamics.
For experimental research, pressure transducers and static pressure probes were applied to investigate the evolution of the internal spout and the local static pressure distribution; optical fibre probes were utilized to measure axial particle velocity profiles and voidage profiles; the step tracer injection technique using helium as the tracer and thermal conductivity cells as detectors was used to investigate the gas mixing behaviour inside a conical spouted bed. It was found that many factors might affect calibration of the effective distance of an optical fibre probe. Therefore, a new calibration setup was designed and assembled, and a comprehensive sensitivity analysis was conducted to calibrate the optical probes used in this study.
For mathematical modelling, a stream-tube model based on the bed structure inside a conical spouted bed was proposed to simulate partial spouting states. By introducing an adjustable parameter, this model is capable of predicting the total pressure drop under different operating conditions, and estimating axial superficial gas velocity profiles and gauge pressure profiles.
A mathematical model based on characteristics of conical spouted beds and the commercial software FLUENT was also developed and validated using measured experimental data. The proposed new CFD model can simulate both stable spouting and partial spouting states, with an adjustable solids-phase source term. At stable spouting states, simulation results agree very well with almost all experimental data, such as static pressure profiles, axial particle velocity profiles, voidage profiles etc. A comprehensive sensitivity analysis was also conducted to investigate the effect of all possible factors on simulation results, including the fluid inlet profile, solid bulk viscosity, frictional viscosity, restitution coefficient, exchange coefficient, and solid phase source term.
The proposed new CFD model was also used successfully to simulate gas mixing behaviours inside a conical spouted bed, and simulate cylindrical packed beds as well as cylindrical fluidized beds in one code package.
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Разаві, Сейед Фаршад. "Гідродинамічні особливості потока аномально-в'язких рідин у конічної поверхні ковзання". Doctoral thesis, Київ, 2019. https://ela.kpi.ua/handle/123456789/29180.
Повний текст джерелаАнотація:
Дисертаційна робота присвячена дослідженню впливу гідродинаміки в'язких і
аномально в'язких мастильних матеріалів у конічних зазорах зі змінною величиною
конусності. Подібні завдання є актуальними при дослідженні конічних опорних
підшипників, які знайшли широке застосування в гідротурбінобудуванні та інших
сферах гідромашинобудування. Одним з важливих питань у даному напрямку є
визначення крутного моменту сил в'язкого тертя в щілинних конічних зазорах.
В роботі, проведено критичний аналіз досліджень, присвячених даній темі, зроблено
висновок про недостатність досліджень і поставлена задача, розв’язання якої
пропонується в даній роботі. На підставі досліджень інших авторів виведені основні
критерії подібності, які можуть охарактеризувати цей процес поведінки рідини в
зазорі, де одна з поверхонь (внутрішня) може обертатися навколо своєї осі. Проведено
фізичне і математичне моделювання поведінки рідини в конічних підшипниках. На
підставі експериментальних досліджень були отримані функціональні залежності
визначення крутного моменту як функції частоти обертання внутрішнього конуса,
в'язкості змащує рідини, ширини щілинного зазору між конічними поверхнями.
Отримані результати були зіставлені з аналогічними даними для циліндричних
щілинних зазорів (циліндричних підшипників ковзання). Представлені рекомендації по
розрахунку основних характеристик потоку. Проведення математичне моделювання
дало можливість оцінити ступінь відмінності між результатами експерименту і теорії,
пояснити розбіжності в результатах. Одним з найважливіших моментів дослідження є
результат, пов'язаний з поведінкою аномально-в'язких рідин (деякі з мастильних
матеріалів за своєю поведінкою близькі до рідин, поведінка яких можна описати
рівнянням Освальда де Віля). Проведене моделювання процесів, що розглядаються в
конічних щілинних зазорах, дало можливість забезпечити раціональний вибір
змащувальних матеріалів для зниження моменту тертя (сил тертя) в конічних зазорах.
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Hroš, Michal. "Optimalizace podmínek dvojitého přetavení elektronovým paprskem v procesu přípravy TBC povlaků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400832.
Повний текст джерелаАнотація:
Thermal barrier coatings (TBCs) are commonly used for thermal protection of components in modern gas turbine application and typically consisting of ceramic top coat and CoNiCrAlY bond coat (BC), both thermally sprayed. Nanostructured CoNiCrAlY bond coatings were deposited onto Ni-based alloy (Inconel 718) by both HVOF and CGDS spraying techniques. Subsequently the deposits were remelted by electron beam up to depth of about 100 m which resulted in removal of defects on the substrate to the bond coat interface. The primary objective of this thesis was to investigation of the influence of parameters used for EB remelting, including multiple remelting on the microstructural changes, phase modification and final state of the coatings. The amount of porosity in the coatings and surface roughness has been evaluated. Scanning electron microscopy and X-Ray diffraction were performed in order to characterize the phase modification before and after the applied treatment. The results indicated that multiple remelting process improved the coating properties in terms of porosity, smooth surface, strength and chemical homogeneity and at last but not least this study demonstrate that low-temperature processing of CoNiCrAlY bond coat represents an interesting and promising alternative for their manufacturing.
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Roy, Jean-Michel L. "Development of Cold Gas Dynamic Spray Nozzle and Comparison of Oxidation Performance of Bond Coats for Aerospace Thermal Barrier Coatings at Temperatures of 1000°C and 1100°C." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20681.
Повний текст джерелаАнотація:
The purpose of this research work was to develop a nozzle capable of depositing dense CoNiCrAlY coatings via cold gas dynamic spray (CGDS) as well as compare the oxidation performance of bond coats manufactured by CGDS, high-velocity oxy-fuel (HVOF) and air plasma spray (APS) at temperatures of 1000°C and 1100°C. The work was divided in two sections, the design and manufacturing of a CGDS nozzle with an optimal profile for the deposition of CoNiCrAlY powders and the comparison of the oxidation performance of CoNiCrAlY bond coats. Throughout this work, it was shown that the quality of coatings deposited via CGDS can be increased by the use of a nozzle of optimal profile and that early formation of protective α-Al2O3 due to an oxidation temperature of 1100°C as opposed to 1000°C is beneficial to the overall oxidation performance of CoNiCrAlY coatings.
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Шудрик, Олександр Леонідович. "Підвищення ефективності використання відцентрових насосів за рахунок вдосконалення математичних моделей робочого процесу". Thesis, НТУ "ХПІ", 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/35499.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.05.17 – гідравлічні машини та гідропневмоагрегати. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2018 р.
Дисертацію присвячено вирішенню важливої науково-технічної задачі підвищення ефективності роботи заглибного електровідцентрового насоса при його роботі на реальній рідині, що представляє собою суміш в'язкої неньютонівської рідини, води та газу, за рахунок вдосконалення математичних моделей. Виконано аналіз концепцій розвитку насособудування в Україні. Описано методи математичного моделювання тривимірних течій в'язкої реальної рідини та їх переваги над фізичними експериментами. Обрано пакет програм для проведення чисельного експерименту в каналах заглибних насосів OpenFOAM. Для моделювання течії рідини в проточній частині насоса використовувалась система рівнянь нерозривності та Навье-Стокса. Для її замикання було обрано k-ε модель турбулентності. Досліджено вплив реологічних властивостей неньютонівських рідин на характеристики відцентрового насоса. Наведено математичну модель турбулентної тривимірної течії неньютонівської рідини. Для розрахунків обрано модель неньютонівської рідини Гершеля-Балклі, що найбільш точно описує поведінку рідин даного типу. Вдосконалено залежності для перерахунку характеристик насосу при його роботі на реальній рідині. Визначено та обрано підхід та математичну модель для моделювання тривимірної течії в'язкої газорідинної суміші та показані особливості при розрахунках такого типу рідин в пакеті OpenFOAM. Розглянуто шляхи підвищення ефективності заглибних насосів шляхом зміни проточної частини. Визначено раціональний кут нахилу вихідної кромки. Запропоновано модифіковану ступінь насоса, котра захищена патентом України, для перекачування рідини з підвищеним вмістом газу. Розглянуто та вдосконалено математичну модель сумісної роботи реальної свердловини та заглибного відцентрового насоса у вигляді пакета прикладних програм. Це дало змогу визначати основні фізичні характеристики рідини в залежності від термодинамічних умов.Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.05.16 – Hydraulic machines and hydropneumatic units. – National Technical University "Kharkiv Politechnic Institute", 2018. The dissertation is devoted to the solution of an important scientific and technical problem of increasing the efficiency of a submersible electric centrifugal pump when it operates on a real liquid, which is a mixture of viscous non-Newtonian fluid, water and gas by improving mathematical models. An analysis of the concepts of development of pumping plant in Ukraine is carried out. The methods of mathematical modeling of three-dimensional flows of a viscous real liquid and their advantages over physical experiments are described. Selected software package for numerical experiment in OpenFOAM submersible pump channels. A system of indeterminate and Navier-Stokes equations was used to simulate the flow of fluid in the flow section of the pump. For its closure a k-ε turbulence model was chosen. The influence of rheological properties of non-Newtonian fluids on the characteristics of a centrifugal pump is investigated. The mathematical model of the turbulent three-dimensional flow of the non-Newtonian fluid is given. For calculations, a model of the Herschel-Bulkley non-Newtonian fluid is chosen, which most accurately describes the behavior of liquids of this type. The dependencies for the recalculation of the characteristics of the pump during its operation on the real liquid have been improved. The approach and mathematical model for modeling the three-dimensional flow of a viscous gas-liquid mixture are determined and chosen, and features are shown in the calculations of this type of fluid in the OpenFOAM package. The ways of increasing the efficiency of submersible pumps by changing the flow part are considered. The rational angle of inclination of the initial edge is determined. The modified degree of the pump, protected by the Ukrainian patent, is offered for pumping a liquid with an increased gas content. The mathematical model of a compatible operation of a real well and a submersible centrifugal pump in the form of a package of applied programs is considered and improved. This made it possible to determine the basic physical characteristics of the liquid, depending on the thermodynamic conditions.
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Шудрик, Олександр Леонідович. "Підвищення ефективності використання відцентрових насосів за рахунок вдосконалення математичних моделей робочого процесу". Thesis, НТУ "ХПІ", 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/35496.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.05.17 – гідравлічні машини та гідропневмоагрегати. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2018 р.
Дисертацію присвячено вирішенню важливої науково-технічної задачі підвищення ефективності роботи заглибного електровідцентрового насоса при його роботі на реальній рідині, що представляє собою суміш в'язкої неньютонівської рідини, води та газу, за рахунок вдосконалення математичних моделей. Виконано аналіз концепцій розвитку насособудування в Україні. Описано методи математичного моделювання тривимірних течій в'язкої реальної рідини та їх переваги над фізичними експериментами. Обрано пакет програм для проведення чисельного експерименту в каналах заглибних насосів OpenFOAM. Для моделювання течії рідини в проточній частині насоса використовувалась система рівнянь нерозривності та Навье-Стокса. Для її замикання було обрано k-ε модель турбулентності. Досліджено вплив реологічних властивостей неньютонівських рідин на характеристики відцентрового насоса. Наведено математичну модель турбулентної тривимірної течії неньютонівської рідини. Для розрахунків обрано модель неньютонівської рідини Гершеля-Балклі, що найбільш точно описує поведінку рідин даного типу. Вдосконалено залежності для перерахунку характеристик насосу при його роботі на реальній рідині. Визначено та обрано підхід та математичну модель для моделювання тривимірної течії в'язкої газорідинної суміші та показані особливості при розрахунках такого типу рідин в пакеті OpenFOAM. Розглянуто шляхи підвищення ефективності заглибних насосів шляхом зміни проточної частини. Визначено раціональний кут нахилу вихідної кромки. Запропоновано модифіковану ступінь насоса, котра захищена патентом України, для перекачування рідини з підвищеним вмістом газу. Розглянуто та вдосконалено математичну модель сумісної роботи реальної свердловини та заглибного відцентрового насоса у вигляді пакета прикладних програм. Це дало змогу визначати основні фізичні характеристики рідини в залежності від термодинамічних умов.Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.05.16 – Hydraulic machines and hydropneumatic units. – National Technical University "Kharkiv Politechnic Institute", 2018. The dissertation is devoted to the solution of an important scientific and technical problem of increasing the efficiency of a submersible electric centrifugal pump when it operates on a real liquid, which is a mixture of viscous non-Newtonian fluid, water and gas by improving mathematical models. An analysis of the concepts of development of pumping plant in Ukraine is carried out. The methods of mathematical modeling of three-dimensional flows of a viscous real liquid and their advantages over physical experiments are described. Selected software package for numerical experiment in OpenFOAM submersible pump channels. A system of indeterminate and Navier-Stokes equations was used to simulate the flow of fluid in the flow section of the pump. For its closure a k-ε turbulence model was chosen. The influence of rheological properties of non-Newtonian fluids on the characteristics of a centrifugal pump is investigated. The mathematical model of the turbulent three-dimensional flow of the non-Newtonian fluid is given. For calculations, a model of the Herschel-Bulkley non-Newtonian fluid is chosen, which most accurately describes the behavior of liquids of this type. The dependencies for the recalculation of the characteristics of the pump during its operation on the real liquid have been improved. The approach and mathematical model for modeling the three-dimensional flow of a viscous gas-liquid mixture are determined and chosen, and features are shown in the calculations of this type of fluid in the OpenFOAM package. The ways of increasing the efficiency of submersible pumps by changing the flow part are considered. The rational angle of inclination of the initial edge is determined. The modified degree of the pump, protected by the Ukrainian patent, is offered for pumping a liquid with an increased gas content. The mathematical model of a compatible operation of a real well and a submersible centrifugal pump in the form of a package of applied programs is considered and improved. This made it possible to determine the basic physical characteristics of the liquid, depending on the thermodynamic conditions.
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Ruf, Hartmut. "Dynamique moléculaire par imagerie attoseconde." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00803390.
Повний текст джерелаАнотація:
Depuis sa première observation, la génération d'harmoniques d'ordre élevé (GHOE) dans les gaz a demontré son importance, ouvrant la voie à la science attoseconde. Cette technique produit un rayonnement impulsionnel XUV qui s'étend dans le domaine spectral intermédiaire entre l'ultraviolet et les rayons X. Ces impulsions attosecondes donnent accès à des résolutions temporelles extrêemes, permettant ainsi d'observer des dynamiques électroniques dans des atomes ou des molécules. En effet le processus de généneration d'harmonique repose sur l'oscillation de paquets d'électrons attosecondes issus des molécules, accélérés par le champ de laser intense et se recombinant radiativement avec leurs ions moléculaires parents. Ainsi, le rayonnement harmonique émis lors de la recombinaison permet d'encoder l'information structurale sur le ou les orbitales impliquées avec une résolution spatiale de l'ordre l'Angström et temporelle femtoseconde ou attoseconde. La génération d'harmonique peut être utilisée comme signal de sonde dans des expériences de spectroscopie pompe-sonde résolue en temps. Ces expériences de spectroscopie harmoniques permettent d'étudier la structure des orbitales et les dynamiques moléculaires ultra-rapides. L'objectif de cette thèse est d'utiliser le processus de la GHOE, pour sonder les processus fondamentaux qui interviennent dans les atomes, les molécules et la matière condensée. Tout d'abord, pour comprendre comment extraire des informations dynamiques ou structurelles sur les orbitales à partir du signal harmonique nous avons étudié un système simple et connu: l'argon. Une nouvelle approche théorique développée par Fabre et Pons a permis de reproduire fidèlement l'expérience. Nous avons continué à étudier la structure et la dynamique moléculaire dans N2 et CO2. Les molécules issues d'un jet supersonique Even-Lavie qui permettait d'obtenir des températures rotationelles de moins de 10K ont été alignées par laser avec un fort degré d'alignement. Ce type de jet permet d'améliorer la sensibilité à la structure des orbitales impliquées et d'identifier la contribution de plusieurs orbitales. Ensuite nous avons utilisé la sensibilité de la génération des harmoniques d'ordre élevé à la structure des orbitales moléculaires pour sonder la dynamique complexe du NO2 excité autour d'une intersection conique. Nous avons appliqué la méthode du réseau d'excitation transitoire qui permet d'améliorer la sensibilité aux molécules excitées. Nous avons donc mené une étude dans les agrégats. A l'aide d'une étude différentielle en température et d'une méthode de cartographie spectrale et spatiale, nous avons pu isoler la contibution des grands agrégats. Notre analyse suggère un nouveau mécanisme de génération par des agrégats et permet même une estimation de la longeur de corrélation des électrons dans les agrégats. Ce manuscrit se termine avec la présentation d'une ligne de lumière XUV. Cette technique consiste à utiliser le rayonnement XUV fs produit par la GHOE comme impulsion sonde pour ioniser des fragments de dissociation moléculaire à l'aide d'une transition à un photon.
Книги з теми "Conical gap"
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Zhou, S. Y., and A. Lanzara. The electronic structure of epitaxial graphene—A view from angle-resolved photoemission spectroscopy. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533046.013.14.
Повний текст джерелаАнотація:
This article analyzes the electronic structure of epitaxial graphene using angle-resolved photoemission spectroscopy (ARPES). It first describes how the carbon atoms in graphene are arranged before discussing the growth and characterization of graphene samples. It then considers the electronic structure of epitaxial graphene, along with the gap opening in single-layer epitaxial graphene. It also examines possible mechanisms for the gap opening in graphene, including quantum confinement, mixing of the states between the Brillouin zone corner K points induced by scattering, and hybridization of the valence and conduction bands caused by symmetry breaking in carbon sublattices. Clear deviations from the conical dispersions are observed near the Diracpoint energy, which can be interpreted as a gap opening attributed to graphene–substrate interaction. Graphene–substrate interaction is thus a promising route for engineering the bandgap in graphene.
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M, Price J., Dogra Virendra K, and Langley Research Center, eds. DSMC calcuations for a 70⁰ blunted cone at 3.2km/s in nitrogen. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1995.
Знайти повний текст джерелаЧастини книг з теми "Conical gap"
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Skovorodko, P. A. "The Peculiarities of Condensation Process in Conical Nozzle and in Free Jet Behind it." In Rarefied Gas Dynamics, 1053–61. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2467-6_38.
Повний текст джерела
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Ludescher, Sandra, and Herbert Olivier. "Film Cooling in Rocket Nozzles." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 65–78. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-53847-7_4.
Повний текст джерелаАнотація:
Abstract In this project supersonic, tangential film cooling in the expansion part of a nozzle with rocket-engine like hot gas conditions was investigated. Therefore, a parametric study in a conical nozzle was conducted revealing the most important influencing parameter on film cooling for the presented setup. Additionally, a new axisymmetric film cooling model and a method for calculating the cooling efficiency from experimental data was developed. These models lead to a satisfying correlation of the data. Furthermore, film cooling in a dual-bell nozzle performing in altitude mode was investigated. The aim of these experiments was to show the influence of different contour inflection geometries on the film cooling efficiency in the bell extension.
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Chlamtac, Eden, and Madhur Tulsiani. "Convex Relaxations and Integrality Gaps." In Handbook on Semidefinite, Conic and Polynomial Optimization, 139–69. Boston, MA: Springer US, 2011. http://dx.doi.org/10.1007/978-1-4614-0769-0_6.
Повний текст джерела
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Wolfs, M. J. M., and H. de Jonge. "A NUMERICAL MODEL TO CALCULATE THE GAS LEAKAGE THROUGH A CONICAL PISTON GAP AND TO STUDY THE STABILITY OF A FREE PISTON IN A STIRLING CRYOCOOLER." In Proceedings of the Twelfth International Cryogenic Engineering Conference Southampton, UK, 12–15 July 1988, 566–70. Elsevier, 1988. http://dx.doi.org/10.1016/b978-0-408-01259-1.50111-x.
Повний текст джерела
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"Knudsen-Layer Properties for a Conical Afterbody in Rarefied Hypersonic Flow." In Rarefied Gas Dynamics: Theoretical and Computational Techniques, 462–75. Washington DC: American Institute of Aeronautics and Astronautics, 1989. http://dx.doi.org/10.2514/5.9781600865923.0462.0475.
Повний текст джерела
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Rocco Jr., Leopoldo. "Disintegration of Liquid Sheet Produced by Swirl Injector." In Energetic Materials Research, Applications, and New Technologies, 133–45. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-2903-3.ch006.
Повний текст джерелаАнотація:
The development of liquid sheets that emerges from nozzles is influenced mainly by their initial speed and by the physical properties of the liquid and the ambient gas. A minimum speed of the sheet is necessary for its enlargement against the superficial tension that tends to contract the surface. As this speed increases, the sheet expands until a main extremity is formed, where balance exists among the superficial tension and the inertial forces. The form and regularity of the sheet's disintegration process has influence in the size distribution of the produced drop and in the Sauter mean diameter (SMD). The initial thickness of the produced liquid sheet is important to determine the medium size of obtained drops. It was observed that thicker films produce thicker ligaments and larger drops. The medium drop diameter produced in conical sheets of pressurized swirl atomizers is calculated according to the thickness of the sheets and in the wavelength for the maximum growth tax.
Тези доповідей конференцій з теми "Conical gap"
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Peleg, O., G. Bartal, B. Freedman, O. Manela, M. Segev, and D. N. Christodoulides. "Conical diffraction and gap solitons in honeycomb photonic lattices." In 2007 Quantum Electronics and Laser Science Conference. IEEE, 2007. http://dx.doi.org/10.1109/qels.2007.4431705.
Повний текст джерела
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Peleg, O., G. Bartal, B. Freedman, O. Manela, M. Segev, and D. N. Christodoulides. "Conical Diffraction and Gap Solitons in Honeycomb Photonic Lattices." In Frontiers in Optics. Washington, D.C.: OSA, 2006. http://dx.doi.org/10.1364/fio.2006.ftui4.
Повний текст джерела
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Feng, Zhengkun, and Henri Champliaud. "Analyses of Non-Kinematic Conical Roll Bending Process With Conical Rolls." In ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/detc2010-28882.
Повний текст джерелаАнотація:
High quality cones can be successfully obtained in kinematic conical roll bending process due to the no-sliding between the conical rolls and the plate. However, the performance of the process is limited because the conical rolls cannot be reused to produce other cones with different size. For the purpose of reusing the existing conical rolls to reduce the manufacturing cost, an attachment is added to the top edge of the plate. In such configuration, the top side of the conical rolls slides over the plate to reduce the local velocity near the top edge. The appropriate velocity near the top edge of the plate makes it possible to roll the plate as using the kinematic conical roll bending process. This paper deals with the modeling and simulation of such non-kinematic conical roll bending process based on the finite element method. The numerical simulation results give the relation between the gap size of the bent cone and the friction at the plate/attachment contact. Well bent cones were obtained compared with the ideal cones.
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Duangtang, Pumipong, Piyaporn Krachodnok, and Rangsan Wongsan. "Gain improvement for conventional conical horn by using mushroom-like electromagnetic band gap." In 2014 11th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON). IEEE, 2014. http://dx.doi.org/10.1109/ecticon.2014.6839891.
Повний текст джерела
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Munteanu, Gabriel, Andreas Binder, and Stefan Dewenter. "Five-axis magnetic suspension with two conical air gap bearingless PM synchronous half-motors." In 2012 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM 2012). IEEE, 2012. http://dx.doi.org/10.1109/speedam.2012.6264414.
Повний текст джерела
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Dash, Upali Aparajita, Sudhakar Sahu, and Jyoti Ranjan Panda. "A compact truncated conical Dielectric Resonator Antenna with concentric cylindrical air gap for microwave application." In 2015 International Conference on Microwave, Optical and Communication Engineering (ICMOCE). IEEE, 2015. http://dx.doi.org/10.1109/icmoce.2015.7489781.
Повний текст джерела
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Li, Sheng-Bo, Korneev A. Yu, and Hong-Yuan Jiang. "Notice of Retraction: The determination of the complete gap function in different types of conical bearings." In 2010 International Conference on Machine Learning and Cybernetics (ICMLC 2010). IEEE, 2010. http://dx.doi.org/10.1109/icmlc.2010.5580899.
Повний текст джерела
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Ozawa, Mamoru, R. Matsumoto, K. Matsui, and T. Ishikawa. "CONVECTION PATTERN TRANSITION IN AN ANNULAR GAP AROUND A TRUNCATED CONICAL ROTOR IN A CIRCULAR CYLINDER." In Annals of the Assembly for International Heat Transfer Conference 13. Begell House Inc., 2006. http://dx.doi.org/10.1615/ihtc13.p20.160.
Повний текст джерела
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Dash, Upali Aparajita, and Sudhakar Sahu. "Effects of conical air gap for conformal and central probe feed on Cylindrical Dielectric Resonator Antenna: A behavioral study." In 2015 IEEE Applied Electromagnetics Conference (AEMC). IEEE, 2015. http://dx.doi.org/10.1109/aemc.2015.7509166.
Повний текст джерела
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Matsumoto, Ryosuke, and Mamoru Ozawa. "Flow Pattern Transition and Related Heat Transfer in an Annular Gap Around a Truncated Conical Rotor in a Cylinder." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22874.
Повний текст джерелаАнотація:
Viscous flows in a concentric annulus with rotating inner cylinder was characterized by Taylor-Couette flow. When the inner cylinder is replaced with a truncated conical rotor, the effect of imbalanced centrifugal force induces the meridional circulation flow with a single toroidal vortex. Under non-isothermal condition at cooling the rotor and heating the vessel wall, the flow pattern is drastically changed with the thermal conditions and the rotating speed. This paper describes the vortex flow-pattern transition and related heat transfer of the mixed convection in such a system. The temperature and flow field were visualized by means of thermo-sensitive liquid-crystal tracers. At the same time, the local heat transfer distributions on the cylindrical vessel wall were measured under a uniform heat flux by the electrically-conductive transparent film. Based on the experimental findings is described the interaction between the heat transfer and the thermal flow field during the unsteady mixed convection in the annular gap.