Download or read book An Investigation of Labyrinth Seal Flow Fields Using Computational Fluid Dynamics written by Nandita Mohleji and published by . This book was released on 2007 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation of the Flow Field in 3D Eccentric Annular and 2D Centered Labyrinth Seals for Comparison with Experimental LDA Data written by Anand Vijaykumar and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The flow field in an annular seal is simulated for synchronous circular whirl orbits with 60Hz whirl frequency and a clearance/radius ratio of 0.0154 using the Fluent Computational Fluid Dynamics (CFD) code. Fluent's Moving Reference Frame model (MRF) is used to render the flow quasi-steady by making transformations to a rotating frame. The computed flow fields for velocity, pressure and shear stress measurements are compared with the experimental data of Winslow, Thames and Cusano. The CFD predictions are found to be in good agreement with the experimental results. The present CFD methodology can be extended to other whirl frequencies and clearances. The dynamic wall pressure distributions in an annular seal for non-circular whirl orbits were obtained using CFD. The simulations were performed using a time dependant solver utilizing Fluent's Dynamic Mesh model and User Defined Functions (UDFs). The wall pressure distributions obtained from the simulations are compared with data of Cusano. The CFD simulations over predicted the pressure field when compared to experimental results however the general trends in pressure contours are similar. The flow fields for varying rotor eccentricities are also studied by performing coordinate transformations and rendering the flow quasi-steady at set eccentricities using Fluent's MRF model. The computed velocity and pressure fields are compared with the time dependant solution obtained using Fluent's Dynamic Mesh model and UDFs for the same eccentricity. Good agreement in the velocity fields is obtained; however the pressure fields require further investigation. 2D Labyrinth seal simulations were performed for comparisons with experimental LDA data from Johnson. The velocity fields match the experimental LDA data to a fair degree of extent; however, Fluent simulations under predicted the secondary recirculation zones in Labyrinth Backward Swirl (LBS) case.

Download or read book The Experimental and Numerical Investigation of the Influence of Shaft Rotation on Leakage Rate of Non contacting Seals Found in Turbine Applications written by Jacobus Johannes Fourie Wiid and published by . This book was released on 2018 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project was initiated by ESKOM power generation. ESKOM loses up to 22% of their steam energy in the HP turbines due to leakage at the turbine labyrinth seals. Therefore the need was expressed their need to implement improved sealing configurations. The aim of this study is to investigate the effect that shaft rotation has on the leakage rate of labyrinth and brush seals. This is done by means of experimental and numerical methods. For many decades it was assumed that the shaft rotation has no or little effect on seal performance and therefore it was neglected in seal design. It was decided to investigate this subject, in order to assist and improve in future seal design and operation. Both labyrinth and brush seals were investigated experimentally on a test rig. A real life application of the labyrinth or brush seals can be found in the power generation industry where a turbine shaft has a diameter of 300 mm and rotates at 3 000 rpm. The test rig was designed to assist in this application. Therefor the test rig had a shaft diameter of 150 mm with shaft speeds ranging between 0-10 000 rpm and with five different upstream pressures ranging from 1-5 bar. The same seals were then simulated using the commercial Computational Fluid Dynamics (CFD) package STAR-CCM+ with the bristle pack of the brush seal modelled as a porous medium. The coefficients of resistance for the porous medium were experimentally obtained. The two investigation methods are compared for the labyrinth and brush seals. The labyrinth and brush seals are also compared against each other. The results show that the experimental leakage rates have a good correlation with those predicted by CFD. The CFD simulation provided detailed leakage flow fields and pressure distributions of both seals. It was found that shaft rotation has an influence on the leakage rate of both seals. The leakage rate increased at higher shaft speeds, with the brush seal performing better than the labyrinth seal. An increase of up to 1.7% was found at 10 000 rpm for the labyrinth seal and 1.45% for the brush seal at 10 000 rpm. Guidelines were created based on these results to assist with advanced seal design. It is recommended that these guidelines are used in future seal design and other research aspects of non-contacting seals in turbo machinery.

Download or read book Numerical Analytical Experimental Study of Fluid Dynamic Forces in Seals Volume 5 Description of Seal Dynamics Code Dyseal and Labyrinth Seals Code Ktk written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-15 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of the program were to develop computational fluid dynamics (CFD) codes and simpler industrial codes for analyzing and designing advanced seals for air-breathing and space propulsion engines. The CFD code SCISEAL is capable of producing full three-dimensional flow field information for a variety of cylindrical configurations. An implicit multidomain capability allow the division of complex flow domains to allow optimum use of computational cells. SCISEAL also has the unique capability to produce cross-coupled stiffness and damping coefficients for rotordynamic computations. The industrial codes consist of a series of separate stand-alone modules designed for expeditious parametric analyses and optimization of a wide variety of cylindrical and face seals. Coupled through a Knowledge-Based System (KBS) that provides a user-friendly Graphical User Interface (GUI), the industrial codes are PC based using an OS/2 operating system. These codes were designed to treat film seals where a clearance exists between the rotating and stationary components. Leakage is inhibited by surface roughness, small but stiff clearance films, and viscous pumping devices. The codes have demonstrated to be a valuable resource for seal development of future air-breathing and space propulsion engines Shapiro, Wilbur and Chupp, Raymond and Holle, Glenn and Scott, Thomas Glenn Research Center NAS3-25644; WBS 22-00-00

Download or read book A Numerical Investigation of Labyrinth Seal Flutter written by Richard Phibel and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigates numerically the phenomenon of flutter in Labyrinth seals. Computational fluid dynamics (CFD) methods are used to predict the fluid forces produced in the labyrinth when one of the seal members is vibrating in its natural mode. The geometry of the seal, the vibrational characteristics and the flow characteristics are varied to determine their influence on the aeroelastic stability. The CFD results are used to develop a bulk-flow model for labyrinth seal flutter analysis. An aeroelastic design procedure for labyrinth seal is pro- posed.

Download or read book Numerical Simulation of Flow in a Whirling Annular Seal and Comparison With Experiments written by and published by . This book was released on 1996 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Leakage Flow in Labyrinth Seals written by Mohammed Ajaz Khan and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Computational Fluid Dynamic Study of Subsonic Compressible Flow in a Labyrinth Seal written by Lily J. Ho and published by . This book was released on 2001 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Labyrinth Seal Leakage Analysis written by Gaurav Chaudhary and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Seals are basic mechanical devices commonly used in machinery to avoid undesired flow losses of working fluids. To understand the working of these seals specifically those placed between relatively moving parts is still one of the major engineering challenges for the scientific community. Particularly Annular seals are one of the most widely used in rotating machinery comprising turbines, compressors and pumps. They are mounted on the shaft that rotates within a stationary case. These seal designs make an impact on (i) machinery energy conversion efficiency and (ii) rotor dynamic stability due to the interaction between rotor and stator through fluid flow leakage. Among all annular seals straight through rectangular labyrinth seals are the most commonly used ones. Their designs have not changed much a lot since its inception by C.J. Parsons [1] back in 1901. These seals provide resistance to the fluid flow through tortuous path comprising of series of cavities and clearances. The sharp tooth converts the pressure energy to the kinetic which is dissipated through turbulence viscosity interaction in the cavity. To understand the accurate amount of leakage the flow is modeled using the discharge coefficient and for each tooth and the kinetic energy carry over coefficients. This research work is aimed at understanding the fluid flow though labyrinth seals with tooth mounted on the rotor. A matrix of fluid flow simulations has been carried out using commercially available CFD software Fluent® where all parameters effecting the flow field has been studied to understand their effect on the coefficients defining the seal losses. Also the rotor surface speed has been used varied in a step by step manner to understand the fluid flow behavior in high speed turbo-machinery. The carry over coefficient is found to be the function of all the geometric elements defining the labyrinth tooth configuration. A relation between the flow parameters and the carry over coefficient has also been established. The discharge coefficient of the first tooth has been found to be lower and varying in a different manner as compared to a tooth from a multiple cavity seal. Its dependence upon flow parameters and dimensionless geometric constants has been established. The discharge coefficient of the first teeth is found to be increasing with increasing tooth width. Further the compressibility factor has been defined to incorporate the deviation of the performance of seals with compressible fluid to that with the incompressible flow. Its dependence upon pressure ratio and shaft speed has also been established. Using all the above the mentioned relations it would be easy decide upon the tooth configuration for a given rotating machinery or understand the behavior of the seal currently in use.

Download or read book Leakage Prediction of Labyrinth Seals Having Advanced Cavity Shapes written by Sunil Murlidher Panicker and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Labyrinth seals are widely used in various turbo machines including turbines, compressors and pumps. Their purpose is to prevent the backflow of the working fluid. This backflow is due to the leakage of the seal. This loss affects the efficiency of the turbo machine, so it becomes critically important to assess the leakage of the seals under the given operating conditions. The accuracy of prediction of leakage is also important for performing rotodynamic analysis. The geometric shape of the seal plays an important role in influencing the fluid flowing through the seals and the leakage rate. Many empirical seal leakage prediction models, useful from a design/analysis point of view, have been developed. Saikishan Suryanarayanan and Gerald. L .Morrison studied the influence of various geometric and flow parameters on the leakage of labyrinth seals with rectangular cavities. They proposed a leakage equation based on their Computational Fluid Dynamics (CFD) simulations using software FLUENT. However, many real world labyrinth seals do not have simple rectangular cavities. In particular, this thesis focuses on seals with Isosceles triangle shaped teeth, right triangle shaped teeth, and a NASA seal. In the present work, CFD simulations of labyrinth seals with advanced cavity shapes are performed and the results are compared with the predictions of the rectangular seal model. The results show that the advanced cavities like, Isosceles shaped seal were more efficient as compared to rectangular seals. The pressure drop, which was taken as one of the key parameters to adjudge the efficiency of seals showed negative behavior in some of the advanced cavity shaped seal. The advanced cavity shaped seals are used in various turbo machinery equipments like steam and gas turbines. This study shows that Isosceles cavity shaped seals are the most efficient among all the advanced cavity shapes used in the present study.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book Investigation of the Performance of Labyrinth Seals for Centrifugal Compressor Applications written by Casey Palanca and published by . This book was released on 2022 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Labyrinth seals were one of the first seal configurations used in modern turbomachinery and, due to their robust qualities and relatively low-cost productions, remain one of the most widely used seal configurations today. Their primary purpose is to control internal leakage between the rotating and stationary components of rotating machinery, including the centrifugal compressor. A reduction in secondary leakage flow will always be accompanied by an increase in efficiency. However, while fulfilling the objective of restricting secondary fluid flow, labyrinth seals have been known to cause adverse stability effects on the rotor. Driving forces inside the cavities from the circumferential flow path have been known to be a potential source of destabilizing vibrations. Therefore, accurately predicting these forces is a primary interest in compressor design. These forces are characterized by stiffness and damping coefficients.The present study utilizes the growing advances in CFD to understand, model, and predict the aerodynamic and rotordynamic performance of labyrinth seals. The scope of this work progresses from a well-established steady state CFD method to a more novel transient CFD approach. The benefits and disadvantages of each method are evaluated and discussed by comparing accuracy, reliability, and computational efficiency. Each method is validated with experimental data. Additionally, the proposed transient CFD method can be used to perform a reasonably accurate prediction of the frequency-dependent rotordynamic coefficients by using a Fast Fourier Transform analysis on the monitored force response and displacement data.Lastly, the transient CFD approach is expanded upon by investigating the flow characteristics of long 18 tooth on rotor balance piston labyrinth seal modeled with abradable grooves on the stator. It was discovered that the creation of abradable grooves on the stator can cause the vortex between the labyrinth teeth to change directions (clockwise to counterclockwise). This observation is used to determine the relationship between the flow pattern and rotordynamic performance. A parametric study shows the effect of abradable groove geometries and operating flow conditions on the labyrinth seal rotordynamic coefficients.

Download or read book A Comparative Investigation of Corresponding Annular and Labyrinth Seal Flowfields written by D. L. Rhode and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A previous Navier-Stokes finite difference computer code is extended in order to compute seal leakage directly from given upstream and downstream reservoir pressures. The numerical results are in excellent agreement with previous measurements, the discrepancy being less than eight percent. Annual seals are found to leak approximately twenty percent more than corresponding labyrinths over the entire range of realistic clearance. A rather unexpected finding is that a dramatic increase of swirl velocity occurs near the discharge of small clearance annular seals, which does not arise in corresponding labyrinth seals. The results, which are used to explain this finding, show that a large density drop occurs near the small clearance annular seal exit, which provides the swirl velocity increase in accordance with angular momentum conservation.

Download or read book A Novel Isolation Curtain to Reduce Turbine Ingress Heating and an Advanced Model for Honeycomb Labyrinth Seals written by Dong Chun Choi and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A combination of 3-D and 2-D computational fluid dynamics (CFD) modeling as well as experimental testing of the labyrinth seal with hexagonal honeycomb cells on the stator wall was performed. For the 3-D and 2-D CFD models, the hexagonal honeycomb structure was modeled using the concept of the baffle (zero-thickness wall) and the simplified 2-D fin, respectively. The 3-D model showed that even a small axial change of the tooth (or honeycomb wall) location, or a small circumferential change of the honeycomb wall location significantly affected the flow patterns and leakage characteristics especially for small tooth tip clearance. Also, the local details of the flow field were investigated. The seven basic procedural steps to develop a 2-D axisymmetric honeycomb labyrinth seal leakage model were shown. Clearly demonstrated for varying test conditions was the 2-D model capability to predict the 3-D honeycomb labyrinth flow that had been measured at different operating conditions from that used in developing the2-D model. Specifically, the 2-D model showed very close agreement with measurements. In addition, the 2-D model greatly reduced the computer resource requirement needed to obtain a solution of the 3-D honeycomb labyrinth seal leakage. The novel and advanced strategy to reduce the turbine ingress heating, and thus the coolant requirement, by injecting a "coolant isolation curtain" was developed numerically using a 3-D CFD model. The coolant isolation curtain was applied under the nozzle guide vane platform for the forward cavity of a turbine stage. Specifically, the isolation curtain serves to isolate the hot mainstream gas from the turbine outer region. The effect of the geometry change, the outer cavity axial gap clearance, the circumferential location of the injection curtain slot and the injection fluid angle on the ingress heating was investigated. Adding the chamfer to the baseline design gave asimilar or higher maximum temperature T*max than did the baseline design withoutchamfer, but implementation of the injection curtain slot reduced substantially T*max of the outer region. In addition, a more desirable uniform adiabatic wall temperature distribution along the outer rotor and stator surfaces was observed due to the presence of the isolation curtain.

Download or read book Rotordynamics Prediction in Engineering written by Michel Lalanne and published by John Wiley & Sons. This book was released on 1998-02-04 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this updated and revised second edition, the authors present a systematic and practical approach to the analytical and numerical aspects of the prediction of rotordynamics behaviour. The influence of bending is a main theme of the book, although the effects of torsion are also considered. The use of finite element techniques and the characteristics of rotor elements are introduced. The book goes on to consider simple models showing basic phenomena which are then linked to industrial applications such as turbocompressors, high pressure centrifugal compressors, and steam and air turbines. Key features include: The inclusion of a computer program available free of charge on the Internet The development of a simple model of co-axial multirotors New industrial applications and 1995 API specifications This book will be of great interest and value to students and engineers concerned with predictions in rotordynamics and mechanical engineering.

Download or read book Numerical Analytical Experimental Study of Fluid Dynamic Forces in Seals Volume 2 Description of Gas Seal Codes Gcylt and Gface written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-15 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of the program were to develop computational fluid dynamics (CFD) codes and simpler industrial codes for analyzing and designing advanced seals for air-breathing and space propulsion engines. The CFD code SCISEAL is capable of producing full three-dimensional flow field information for a variety of cylindrical configurations. An implicit multidomain capability allow the division of complex flow domains to allow optimum use of computational cells. SCISEAL also has the unique capability to produce cross-coupled stiffness and damping coefficients for rotordynamic computations. The industrial codes consist of a series of separate stand-alone modules designed for expeditious parametric analyses and optimization of a wide variety of cylindrical and face seals. Coupled through a Knowledge-Based System (KBS) that provides a user-friendly Graphical User Interface (GUI), the industrial codes are PC based using an OS/2 operating system. These codes were designed to treat film seals where a clearance exists between the rotating and stationary components. Leakage is inhibited by surface roughness, small but stiff clearance films, and viscous pumping devices. The codes have demonstrated to be a valuable resource for seal development of future air-breathing and space propulsion engines. Liang, Anita D. (Technical Monitor) and Shapiro, Wilbur Glenn Research Center NAS3-25644; WBS 22-5000-0013

Download or read book Numerical Analytical Experimental Study of Fluid Dynamic Forces in Seals Volume 4 Description of Incompressible Fluid Seal Codes Icyl and Iface written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-03 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of the program were to develop computational fluid dynamics (CFD) codes and simpler industrial codes for analyzing and designing advanced seals for air-breathing and space propulsion engines. The CFD code SCISEAL is capable of producing full three-dimensional flow field information for a variety of cylindrical configurations. An implicit multidomain capability allow the division of complex flow domains to allow optimum use of computational cells. SCISEAL also has the unique capability to produce cross-coupled stiffness and damping coefficients for rotordynamic computations. The industrial codes consist of a series of separate stand-alone modules designed for expeditious parametric analyses and optimization of a wide variety of cylindrical and face seals. Coupled through a Knowledge-Based System (KBS) that provides a user-friendly Graphical User Interface (GUI), the industrial codes are PC based using an OS/2 operating system. These codes were designed to treat film seals where a clearance exists between the rotating and stationary components. Leakage is inhibited by surface roughness, small but stiff clearance films, and viscous pumping devices. The codes have demonstrated to be a valuable resource for seal development of future air-breathing and space propulsion engines.Liang, Anita D. (Technical Monitor) and Artiles, AntonioGlenn Research CenterSEALS (STOPPERS); COMPUTATIONAL FLUID DYNAMICS; AIR BREATHING ENGINES; FLOW DISTRIBUTION; ROTOR DYNAMICS; THREE DIMENSIONAL FLOW; CYLINDRICAL BODIES; GRAPHICAL USER INTERFACE; EXPERT SYSTEMS