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Littérature scientifique sur le sujet « Radial segmented seals »
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Articles de revues sur le sujet "Radial segmented seals"
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Birch, Philip, et Jamie Haynes. « The Pierce Field, Blocks 23/22a, 23/27, UK North Sea ». Geological Society, London, Memoirs 20, no 1 (2003) : 647–59. http://dx.doi.org/10.1144/gsl.mem.2003.020.01.51.
Texte intégralRésumé :
AbstractThe Pierce Field contains oil and gas in Palaeocene Forties Sand and fractured Chalk, draped around the flanks of a pair of Central Graben salt diapirs. Whilst the two diapirs constitute a single field containing over 387 MMSTB AND 125 BCF, it took almost 25 years, and several advances in seismic, drilling and production technology, for the field to be brought into production. Many appraisal wells were drilled on the field. Data from these wells were interpreted to suggest the field was highly segmented both in terms of petroleum distribution and pressure variance. On the basis of this interpretation an economic development required a floating production system with long reach horizontal wells to penetrate the many reservoir segments. The results of development drilling have indicated that few pressure seals exist within the field, with concentric faults being more likely to seal than radial faults. The various reservoir pressures and oil-water contacts have been re-interpreted as a single, highly tilted oil-water contact, facilitated by the location of the field in the low permeability toe of the Forties submarine fan, a major conduit for the transport of basinal fluids away from the deep Central GrabenPalaeocene reservoir depositional patterns closely resemble those predicted by analogue models. The greatest reservoir thickness and net/gross are located in areas of flow velocity reduction (depletive flow), on the 'lee' side of the diapirs, but porosity and permeability are optimized in areas of increased flow velocity (accumulative flow), towards the crests of the diapirsStrontium residual salt analysis has been used to study the charge history of the field. Interpretation suggests that South Pierce was filled before North Pierce, from a local Upper Jurassic source kitchen. Oil and gas subsequently spilled into North Pierce to form a composite trap with a single, tilted oil-water contact. The South Pierce gas cap has since been breached, and the escape of gas is currently leading to the retreat of the tilted water contact, once again isolating the two diapir structures
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Li, Chuantian, Yingfeng Sun, Shiyue Wu et Xiaoyuan Sun. « Investigation on the Gas Drainage Effectiveness from Coal Seams by Parallel Boreholes ». Sustainability 15, no 2 (4 janvier 2023) : 942. http://dx.doi.org/10.3390/su15020942.
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Gas drainage is an important technology to prevent coal and gas outburst, and the drained gas is a kind of clean energy. The gas pressure can characterize gas drainage effectiveness. In this paper, we investigated the effectiveness of gas drainage by gas pressure. Determined by the space shape of the gas flow field, the gas flow state surrounding the drainage boreholes is radial flow. According to the basic equations of radial flow, discrete equations were achieved by the implicit difference scheme, and then we obtained the gas pressure surrounding the drainage boreholes. Results showed that the midpoint between two holes presents the highest gas pressure, and gas pressure declined from the midpoint of two boreholes to both sides. The midpoint gas pressure of the two holes reflects gas drainage effectiveness in a certain degree. Gas pressure declined with segmented characteristics in the first period decline curve in the form of a cubic curve, and the second period decline curve in the form of a straight line. When the drainage pressure reaches a certain value, the decline rate of gas pressure had little relationship with the drainage negative pressure, mainly influenced by the permeability coefficient. To improve the drainage effectiveness, anti-reflection measures are feasible, instead of increasing the drainage negative pressure. Moreover, the conclusion was verified by field data.
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Pugachev, Alexander O., Manuel Gaszner, Christos Georgakis et Paul Cooper. « Segmentation Effects on Brush Seal Leakage and Rotordynamic Coefficients ». Journal of Engineering for Gas Turbines and Power 138, no 3 (22 septembre 2015). http://dx.doi.org/10.1115/1.4031386.
Texte intégralRésumé :
This paper studies the effect of brush seal segmentation on the seal performance characteristics. A brush–labyrinth sealing configuration arranged of one brush seal downstream and two labyrinth fins upstream is studied experimentally and theoretically. The studied brush seal is of welded design installed with zero cold radial clearance. The brush seal front and back rings as well as the bristle pack are segmented radially in a single plane using the electrical discharge machining (EDM) technique. The segmentation procedure results in loss of bristles at the site of the cuts altering the leakage flow structure in the seal and its performance characteristics. Two test rigs are used to obtain leakage, as well as rotordynamic stiffness and damping coefficients of the seal at different pressure ratios. The computational fluid dynamics (CFD)-based model is used to predict the seal performance and to study in detail local changes in the flow field due to the segmentation. A back-to-back comparison of the performance of nonsegmented and segmented brush seals as well as baseline labyrinth seal is provided. The obtained results demonstrate that the segmentation in general negatively affects the performance of the studied brush–labyrinth sealing configuration. However, the segmented brush seal shows increased direct damping coefficients.
Thèses sur le sujet "Radial segmented seals"
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Fourt, Erwan. « Étude de joints radiaux en carbone graphite avec application aéronautique ». Electronic Thesis or Diss., Poitiers, 2021. http://www.theses.fr/2021POIT2292.
Texte intégralRésumé :
Cette thèse a pour but d’étudier expérimentalement plusieurs technologies de joints radiaux segmentés. L’introduction permet de situer le contexte du travail tout en évoquant plusieurs technologies d’étanchéités couramment employées dans les moteurs aéronautiques. Au cours de ce chapitre, les contraintes auxquelles les joints radiaux segmentés doivent faire face sont également détaillées. La première étude menée a pour but d’étudier trois technologies différentes de joints radiaux segmentés : sans poche, avec poche sur les patins et enfin une technologie de joint sans poche en vis-à-vis de rainures inclinées sur le rotor. Dans un premier temps, les performances de chaque étanchéité sont évaluées et comparées.Ensuite, une étude métrologique a été menée sur la technologie de joint sans poche afin d’investiguer l’usure subie par ce dernier au cours des essais. Au cours de ce travail, la fragilité de ce type d’étanchéité a été mis en avant. C’est pourquoi, des joints similaires présentant une défaillance ont été étudiés. Comme précédemment, les performances de ces joints ainsi que l’usure subie ont été évaluées. Il a été montré que malgré la défaillance, ces joints n’ont montré aucun signe de détérioration supplémentaire.Enfin, l’influence de la rugosité de surface a été étudié afin de mettre en avant les phénomènes liés au soulèvement des segments. Pour cela, une méthode numérique multi-échelles a été développée. Il a été montré que cette dernière permettait de résoudre un tel problème avec un effort de calcul faible en comparaison des méthodes standardThe main goal of this thesis is the experimental study of several technologies of radial segmented seals. First of all, an introduction presents the context of the study by detailing the most commonly used seals technologies in aero engines.Firstly, three different technologies of radial segmented seals have been studied: without pocket, with pocket and without pocket and inclined grooves on the rotor. The performance of each technologies has been investigated and compared. In complement, the wear of the pocket-free technology has been study. The work highlights the fragility of this kind of seals. It is why the performance and the wear of faulty seals have been investigated.This second study shows that despite the failure, the seals do not show more serious complications.Then, the impact of roughness on a gas flow was investigate to highlight the lift effect of the segments. For this, a multiscale method was developed. It was shown that this method works well to study such a problem with a very low computational effort in comparison with two other existent methods
Actes de conférences sur le sujet "Radial segmented seals"
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Fourt, Erwan, Mihai Arghir, Pascal Jolly et Mohamed Andasmas. « Experimental Analysis of the Leakage Characteristics of Three Types of Annular Segmented Seals ». Dans ASME Turbo Expo 2022 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-80195.
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Abstract This paper presents an experimental analysis of the leakage characteristics of three kind of segmented seals. The segments of the first seal has smooth pads while the second seal has pads with pockets. The pads of the third seal are smooth but the rotor is textured with inclined grooves. The pockets or the textures lift the segments from the rotor and create a radial clearance. This is reflected by the leakage flow rate, the friction torque and the seal’s temperature. These characteristics are hereby measured on a dedicated test rig. The presented results are dimensionless, the measured values for the three types of seals types being divided by the same maximum value. This makes it possible to compare the performance of different segmented seal technologies. The assumptions made on the position of the segment during the tests (opened or closed against the rotor) are thus verified.
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Arghir, Mihai, et Samia Dahite. « Numerical Analysis of Lift Generation in a Radial Segmented Gas Seal ». Dans ASME Turbo Expo 2019 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90492.
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Abstract A radial segmented seal is composed of three or six carbon segments that are assembled by a circumferential (garter) spring that presses them against the rotor. Assembled, they take the form of an annular ring. Each segment has several pads that generate a radial lift force depending on the rotor speed. There are many ways of creating effective lift forces. For example, a pocket on the pad creates a lift force because each pad will act as a Rayleigh step bearing. A groove on the rotating shaft will also create a radial lift force on the pad. However, this latter lift force will be unsteady. The aim of the present work is the numerical study of the lift created by a grooved rotor on a pad. Due to the very small operating radial clearances of radial segmented seals (less than 10 μm), the problem can be simplified by analyzing a single pad and a grooved runner. Previous analysis of gas face seals or thrust bearings always considered grooved pads and a smooth runner, even when the runner was grooved. The peculiarity of this study, which is the first of its kind, is considering the unsteady problem of the moving runner grooves. The analysis was performed for a single pad of a radial segmented seal operating with air.
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Pugachev, Alexander O., Manuel Gaszner, Christos Georgakis et Paul Cooper. « Segmentation Effects on Brush Seal Leakage and Rotordynamic Coefficients ». Dans ASME Turbo Expo 2015 : Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42332.
Texte intégralRésumé :
This paper studies the effect of brush seal segmentation on the seal performance characteristics. A brush-labyrinth sealing configuration arranged of one brush seal downstream and two labyrinth fins upstream is studied experimentally and theoretically. The studied brush seal is of welded design installed with zero cold radial clearance. The brush seal front and back rings as well as the bristle pack are segmented radially in a single plane using the electrical discharge machining technique. The segmentation procedure results in loss of bristles at the site of the cuts altering the leakage flow structure in the seal and its performance characteristics. Two test rigs are used to obtain leakage, as well as rotordynamic stiffness and damping coefficients of the seal at different pressure ratios. The CFD-based model is used to predict the seal performance and to study in detail local changes in the flow field due to the segmentation. A back-to-back comparison of the performance of non-segmented and segmented brush seals, as well as baseline labyrinth seal is provided. The obtained results demonstrate that the segmentation in general negatively affects the performance of the studied brush-labyrinth sealing configuration. However, the segmented brush seal shows increased direct damping coefficients.
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Grondahl, Clayton M., et James C. Dudley. « Film Riding Leaf Seals for Improved Shaft Sealing ». Dans ASME Turbo Expo 2010 : Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-23629.
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Turbine shaft seals are vulnerable to rubs caused by thermal distortion, mis-alignment and rotor dynamic vibration that are often not well understood. When seals rub as a machine is brought up to operating conditions performance is compromised due to increased seal leakage. Much effort has been extended in recent years to develop seals that mitigate those losses. This paper presents a seal design with segmented film riding runners capable of non-contacting seal operation during rotor transients. Operating differential seal pressure displaces seal leaves and attached runners toward the rotor surface until balanced by hydrostatic and hydrodynamic lift. Sufficient radial range of operation is provided to follow the rotor seal surface during transients while maintaining a small seal clearance. Seal design features and function will be described and illustrated along with analysis of forces and motions for a sample application. Planned modeling and testing will also be presented. This concept promises enhanced shaft sealing by combining a leaf seal structure that provides a large range of motion to avoid rubs during startup and shutdown with runner elements capable of generating hydrostatic and hydrodynamic lift forces to maintain shaft–seal separation during all rotor displacement transients. Improved turbine performance from small operating seal clearance and extended seal life without rubs are expected benefits of the Film Riding Pressure Actuated Leaf Seal (FRPALS).
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Herrmann, N., K. Dullenkopf et H. J. Bauer. « Flexible Seal Strip Design for Advanced Labyrinth Seals in Turbines ». Dans ASME Turbo Expo 2013 : Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95424.
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The paper discusses the potential benefit of flexible seal strips in labyrinth seals for turbines. By reducing the radial stiffness compared to a standard straight and stiff knife, seal clearance could be reduced without significantly reducing the seal durability and long-term performance. As contact between the seal strips and the rotor can occur especially during transient operating phases, a more flexible design of the seal strips can prevent damage and wear, keeping the discharge rates constantly low. However, the pressure difference across the fin will cause a deflection of the seal strip due to the increased flexibility and thus creating an additional possible risk for an unwanted contact. Pressure balanced designs and supports on the low pressure side are used on the investigated seal designs to eliminate that risk. To give evidence of possible performance gain a standard labyrinth seal configuration is compared to two configurations with segmented and curved seal strips. In a first step, the discharge coefficient and the leakage rates for the nominal seal design are calculated using two-dimensional CFD. In order to investigate the impact of a worn seal tip on the leakage flow, the geometry change due to a rubbing event is simulated with FEA tools. Therefore, a specific high-speed wear model is implemented and calibrated by experimental data, enabling the correct cooling effects and plastic deformation. The discharge coefficient and the leakage mass flow rates of the worn geometry are then again modeled with CFD for the various seal configurations and compared to the unworn state. The study shows that a wise combination of the advantages of flexible curved seal strips can be used to reduce the leakage rates significantly, improving the life time of seal elements at the same time.
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Arghir, Mihai, et Antoine Mariot. « Theoretical Analysis of the Static Characteristics of the Carbon Segmented Seal ». Dans ASME Turbo Expo 2016 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56643.
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The segmented carbon seal is regularly used for sealing bearing chambers of aeronautical turboengines or as part of a buffer seal in space turbopumps. The seal operates with contaminated air or with an inert gas and is made of many identic carbon segments (generally three or six) with reciprocally overlapping ends. The segments are serrated against the rotor by the pressure difference between the upstream and the downstream chambers and by a circumferential (garter) spring. The pressure difference and an axial spring press the segments also against the stator. The inner cylindrical surface of each segment is provided with pads that create an aerodynamic lift proportional to the rotor speed. Following this lift force, the segments of the seal are pushed away from the rotor and the seal opens. The contact between the rotor and the segments is lost and an axial leakage path is thus created. Although it was developed since long, a model for calculating the characteristics of the segmented seal is completely absent from the scientific literature. The goal of the present work is to fill this gap at least for the static characteristics (leakage and torque). The analysis is carried out for a single segment of the seal by supposing that all the segments have the same characteristics. Each segment has a planar motion (i.e. three degrees of freedom) and therefore the film thickness under each pad is not uniform. Given the stationary operating conditions (pressure difference and rotation speed), the present model calculates the equilibrium position of each segment on the bases of the lift and of the friction force acting on the pads, of the friction forces acting on the nose of the seal and of the radial and axial springs. Once found the static equilibrium position, the leakage and the torque of the seal are calculated. A parametric study enlightens the importance of the pad waviness, of the pocket depth and of the spring forces on the characteristics of the segmented seal.
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Xue, Qichao, Xueying Li et Jing Ren. « Numerical Investigations of Flow Structures in Radial Rim Seal and a Modification of the Orifice Model ». Dans ASME Turbo Expo 2022 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-83536.
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Abstract Under the increasing turbine temperature of gas turbine, the thermal bearing capacity of rotor and stator of turbine is increasingly limited, which poses a more severe challenge to the protection means such as rim seal, and requires more detailed estimation of flow and heat transfer of rim seal. One of the most important parameters in the estimation is the sealing efficiency. The Orifice Model is widely used to simplify the prediction of sealing efficiency of various sealing structures. Its advantage is that different structures can be described by the same model. However, further work is needed in the prediction of sealing efficiency for more complex structures or the high radius of the locations such as the interface between the disc cavity and the main flow. In this paper, steady numerical simulation is carried out for a radial rim seal structure, and the numerical results are verified by the experimental results in the disk cavity. The flow phenomenon and the mechanism of ingress flow near the rim seal structure is further studied. It is found that the ingress flow has axial and circumferential inhomogeneity, According to the tangential velocity, the ingress flow presents two distinct and “antagonistic” fluids respectively. On this basis, this paper proposes a modification to the Orifice Model, which determine whether the flow is egress or ingress by the tangential velocity. In addition, according to this method, the two-dimensional distribution of the egress and ingress at the interface near the main flow can be seen, and it can be fitted with a simple multi-segment linear function.
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Kong, Xiaozhi, Gaowen Liu, Yuxin Liu et Qing Feng. « Investigation on the Leakage Flow, Windage Heating and Swirl Development of Rotating Labyrinth Seal in a Compressor Stator Well ». Dans ASME Turbo Expo 2016 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56740.
Texte intégralRésumé :
What make the labyrinth seal in a compressor stator well different from the normal labyrinth seal are the inlet and outlet rotor-stator disc cavities. Due to the presence of rotating disc cavities, the windage heating and the swirl development are remarkable, which can have a great influence on the leakage characteristic. Besides, when compressor operates at different speeds, the rotor and stator grow differently owing to centrifugal expansion and thermal expansion. Hence the tip clearance which determines the leakage mass flow changes with the varying of rotational speed and temperature in the stator well. A rotating test rig with rotational speed 8100rpm and pressure ratio range 1.05∼1.3 was designed for the test of labyrinth seal in a compressor stator well. A cantilevered structure was used to entirely collect the mass flow for an accurate measurement. To know the working tip clearance precisely, the set up tip clearance was measured with plug gauges, while the radial displacements of rotating disc and stationary casing were measured separately with two high precision laser distance sensors. The total temperatures of airflow in the stator well were measured with thermocouples to analyze the proportion of windage heating among the inlet rotating disc cavity, outlet rotating disc cavity, and labyrinth seal segment. The disc and stator casing were manufactured with non-metallic materials to reduce heat dissipation. Furthermore, the circumferential velocity of the leakage flow was measured using probes to reveal the swirl development. Two-dimensional, axisymmetric swirl flow numerical simulations were carried out to provide insight into the flow field details, total temperature variation and swirl flow development in the stator well. The numerical results of discharge coefficient, windage heating and swirl ratio were compared with the experimental data. Of particular note is, the tip clearance of numerical model at a specific rotating speed was set to be the same with the actual working clearance which was measured in the experiment. The inlet and outlet parameters corresponded with the experimental conditions also.
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Johannesson, Tomas. « Partial Meshing of Synchronous Belt Teeth ». Dans ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34548.
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Synchronous belts have been used in power transmissions where synchronization is also needed since the 1940’s. In the 1960’s overhead camshaft engines were introduced and synchronous belts were used as cam belts. This made way for a new standard for belts: improvements were made in materials and profile geometry. These new belts had lower noise emissions and, at the same time, greater durability. Often, both wear and noise are generated when a belt tooth seats or unseats a pulley. A tooth is considered to be fully meshed when the whole belt pitch forms a circular arc. This is not the case for teeth in partial mesh, which occurs in seating and unseating zones. In these zones force peaks are often present. These peaks are believed to arise mainly as a result of two phenomena: one is the overlap effect due to the belt geometry not fitting the pulley, and other is the velocity difference effect. The latter is speed-dependent while the former depends on the belt and pulley profile geometries and the belt teeth positions relative to the pulley. Although force peaks of high magnitude occur, they are present at a such small part of the engagement that their contribution to power transmission can be neglected. This indicates that the positions of the belt pitches relative to the pulley pitches can be established by the load distribution from fully meshed conditions. Although the characteristics of partial mesh teeth have been improved by the introduction of new profiles and materials, problems of durability, noise and transmission error, arising from partially meshed teeth, are still present. Therefore it is important to study belt mechanics in seating and unseating zones. This paper describes a method to calculate force peakson seating and unseating. An overlap area (geometrical interference) is formed by giving belt teeth profiles displacement and checking for interference with the pulley profile. Since it is assumed that the seating and unseating force peaks do not influence the load distribution, the positions of the first and last teeth are superimposed on belt teeth profiles using the results from a quasi-static load distribution model covering fully meshed conditions. The superimposed first and last belt teeth profiles are modelled by line segments. A pulley profile is also modelled by line segments and the profiles are checked for interference. Where interference occur an overlap area is formed. The overlap is translated to a force value via correlation with belt tooth force measurements. Results from the model show good agreement with measurements when force peaks are small. This is due to the fact that the quasi-static load distribution model produces correct belt displacements for these cases. For measured force peaks of higher amplitude the seating and unseating effects are under estimated by the method. The semicircular belt geometry in combination with the hyperelastic nature of the elastomer is probably the reason. A solution is to implement a non-linear force-overlap relation. Another effect not included is the velocity difference effect. The results are sensitive to belt tooth height and radial tooth stiffness.