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 Labyrinth Seal Leakage Analysis written by Orcun Inam and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Annular seals are devices used in turbomachinery to avoid flow losses which reduce efficiency. The dynamic stability of the machine is also improved by the seal. Thus, it is an important subject to understand the flow behavior through the seal. Straight through triangular labyrinth seals are one of the most commonly used types of non-contacting annular seals. The energy dissipation through these seals is achieved by a series of teeth and cavities. As the flow passes above each tooth, a portion of its pressure energy is converted into kinetic energy. A portion of this kinetic energy is dissipated through turbulence-viscosity interaction in the cavity that follows. Moreover, some portion of the pressure energy is also lost through viscosity of the fluid. This research aims to understand the effects of flow parameters and seal geometry on these losses. This will make it possible to estimate the mass flow leakage through the seal. ANSYS Fluent is used to simulate the flow through the seal. The effect of seal geometry is studied by varying clearance, pitch, tooth height, tooth width and upstream side angle. It was found that, amongst other geometrical parameters, tooth clearance and pitch has a strong influence on carryover coefficient. Smaller values of c/s have better kinetic energy dissipation in the cavity. Carryover coefficient is also found to be a function of the Reynolds number and shaft speed. Discharge coefficient of the seal presents the overall efficiency while carryover coefficient only shows the cavity performance. Discharge coefficient is also found to be a strong function of tooth clearance, pitch, Reynolds number and shaft speed. Remaining parameters have smaller effects. It was observed that the discharge coefficient of first tooth is always lower than those of intermediate teeth. The compressibility effects are presented by using an expansion factor which is the ratio of compressible flow discharge coefficient to incompressible flow discharge coefficient. It was found that the expansion factor is fairly independent of geometrical parameters but a strong function of flow parameters. Considering the effects of seal geometry and flow parameters on carryover coefficient, discharge coefficient and expansion factor, the seal geometry is optimized to increase the kinetic energy dissipation and pressure head loss which in turn will reduce the mass flow leakage.

Download or read book Labyrinth Seal Leakage Equation written by Saikishan Suryanarayanan and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A seal is a component used in a turbomachine to reduce internal leakage of the working fluid and to increase the machine's efficiency. The stability of a turbomachine partially depends upon the rotodynamic coefficients of the seal. The integral control volume based rotodynamic coefficient prediction programs are no more accurate than the accuracy of the leakage mass flow rate estimation. Thus an accurate prediction of the mass flow rate through seals is extremely important, especially for rotodynamic analysis of turbomachinery. For labyrinth seals, which are widely used, the energy dissipation is achieved by a series of constrictions and cavities. When the fluid flows through the constriction (under each tooth), a part of the pressure head is converted into kinetic energy, which is dissipated through small scale turbulence-viscosity interaction in the cavity that follows. Therefore, a leakage flow rate prediction equation can be developed by comparing the seal to a series of orifices and cavities. Using this analogy, the mass flow rate is modeled as a function of the flow coefficient under each tooth and the carry over coefficient, which accounts for the turbulent dissipation of kinetic energy in a cavity. This work, based upon FLUENT CFD simulations, initially studies the influence of flow parameters, in addition to geometry, on the carry over coefficient of a cavity, developing a better model for the same. It is found that the Reynolds number and clearance to pitch ratios have a major influence and tooth width has a secondary influence on the carry over coefficient and models for the same were developed for a generic rectangular tooth on stator labyrinth seal. The discharge coefficient of the labyrinth seal tooth (with the preceding cavity) was found to be a function of the discharge coefficient of a single tooth (with no preceding cavity) and the carry over coefficient. The discharge coefficient of a single tooth is established as a function of the Reynolds number and width to clearance ratio of the tooth and a model for the same is developed. It is also verified that this model describes the discharge coefficient of the first tooth in the labyrinth seal. By comparing the coefficients of discharge of compressible flow to that of incompressible flow at the same Reynolds number, the expansion factor was found to depend only upon the pressure ratio and ratio of specific heats. A model for the same was developed. Thus using the developed models, it is possible to compute the leakage mass flow rate as well as the axial distribution of cavity pressure across the seal for known inlet and exit pressures. The model is validated against prior experimental data.

Download or read book Analysis of Leakage Flow and Dynamic Coefficients of Gas Labyrinth Seals Using a Three Control Volume Method written by Jie Zhou and published by . This book was released on 2007 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: A computer code has been developed to predict seal leakage and rotordynamic coefficients. A comparison of leakage flow rate and rotordynamic coefficients is presented between experiments, CFD simulation, the new code prediction and previous analysis.

Download or read book Proceedings of the 6th National Symposium on Rotor Dynamics written by J. S. Rao and published by Springer Nature. This book was released on 2020-10-13 with total page 605 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents select papers presented during the 6th National Symposium on Rotor Dynamics, held at CSIR-NAL, Bangalore, and focuses on the latest trends in rotor dynamics and various challenges encountered in the design of rotating machinery. The book is of interest to researchers from mechanical, aerospace, tribology and power industries, engineering service providers and academics.

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 Labyrinth Seal Analysis Volume 3 Analytical and Experimental Development of a Design Model for Labyrinth Seals written by and published by . This book was released on 1986 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thorough review of the literature concerning labyrinth seals was conducted and the significant geometric and aerodynamic parameters influencing leakage were identified. An extensive data base was accumulated from published and in-house experimental results as the foundation for the development of a design model for labyrinth seals. Full-size two-dimensional seal geometries were tested to extend the data range in key areas. The empirically based model was developed using statistical methods to define correlating equations based the seal parameters. Comparison of the resulting model to experimental data revealed an accuracy of + or - 5%. Flow visualization studies yielded qualitative descriptions of the internal flow fields and loss mechanisms at work in both straight and stepped labyrinth seals. Measurement of pressures and temperatures in the seal cavities provided data for comparison with theoretical predictions. Hot-wire anemometer data for internal velocity profiles were in qualitative agreement with the Navier-Stokes analyses. Volume I summarizes the labyrinth seal analysis model. Volume II presents the user's manual for the analysis model computer code. Volume III contains the experimental results and summarizes the design model based on these empirical data. Volume IV presents the user's manual for the design model computer code. Keywords: Rotating seals, Contactless seals, Gas path seals, Interstage seals, Air leakage in gas turbines.

Download or read book Analysis of Compressible and Incompressible Flows Through See through Labyrinth Seals written by Jeng Won Woo and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The labyrinth seal is a non-contact annular type sealing device used to reduce the internal leakage of the working fluid which is caused by the pressure difference between each stage in a turbomachine. Reducing the leakage mass flow rate of the working fluid through the labyrinth seal is desirable because it improves the efficiency of the turbomachine. The carry-over coefficient, based on the divergence angle of the jet, changed with flow parameters with fixed seal geometry while earlier models expressed the carry-over coefficient solely as a function of seal geometry. For both compressible and incompressible flows, the Reynolds number based on clearance was the only flow parameter which could influence the carry-over coefficient. In the case of incompressible flow based on the simulations for various seal geometries and operating conditions, for a given Reynolds number, the carry-over coefficient strongly depended on radial clearance to tooth width ratio. Moreover, in general, the lower the Reynolds number, the larger is the divergence angle of the jet and this results in a smaller carry-over coefficient at lower Reynolds numbers. However, during transition from laminar to turbulent, the carry-over coefficient reduced initially and once the Reynolds number attained a critical value, the carry-over coefficient increased again. In the case of compressible flow, the carry-over coefficient had been slightly increased if radial clearance to tooth width ratio and radial clearance to tooth pitch ratio were increased. Further, the carry-over coefficient did not considerably change if only radial clearance to tooth width ratio was decreased. The discharge coefficient for compressible and incompressible flows depended only on the Reynolds number based on clearance. The discharge coefficient of the tooth in a single cavity labyrinth seal was equivalent to that in a multiple tooth labyrinth seal indicating that flow downstream had negligible effect on the discharge coefficient. In particular, for compressible fluid under certain flow and seal geometric conditions, the discharge coefficient did not increase with an increase in the Reynolds number. It was correlated to the pressure ratio, Pr. Moreover, it was also related to the fact that the flow of the fluid through the constriction became compressible and the flow eventually became choked. At low pressure ratios (less than 0.7), Saikishan's incompressible model deviated from CFD simulation results. Hence, the effects of compressibility became significant and both the carry-over coefficient compressibility factor and the discharge coefficient compressibility factor needed to be considered and included into the leakage model. The carry-over coefficient compressibility factor, phi, had two linear relationships with positive and negative slopes regarding the pressure ratios. This result was not associated with the seal geometry because the seal geometry ratios for each instance were located within the nearly same ranges. Further, the phi-Pr relationship was independent of the number of teeth regardless of single and multiple cavity labyrinth seals. The discharge coefficient compressibility factor, psi, was a linear relationship with pressure ratios across the tooth as Saikishan predicted. However, in certain flow and seal geometric conditions, Saikishan's model needed to be modified for the deviation appearing when the pressure ratios were decreased. Hence, a modified psi-Pr relationship including Saikishan's model was presented in order to compensate for the deviation between the simulations and his model.

Download or read book Compressor Performance written by Theodore Gresh and published by Newnes. This book was released on 2001-05-17 with total page 215 pages. Available in PDF, EPUB and Kindle. Book excerpt: Compressor Performance is a reference book and CD-ROM for compressor design engineers and compressor maintenance engineers, as well as engineering students. The book covers the full spectrum of information needed for an individual to select, operate, test and maintain axial or centrifugal compressors. It includes basic aerodynamic theory to provide the user with the "how's" and "why's" of compressor design. Maintenance engineers will especially appreciate the troubleshooting guidelines offered. Includes many example problems and reference data such as gas properties and flow meter calculations to enable easy analysis of compressor performance in practice. Includes companion CD with computer programs.M. Theodore Gresh has been with the Elliot Company in Jeannette, Pennsylvania, since 1975, initially working on the mechanical and aerodynamic design and application of centrifugal compressors.Unrivalled coverage of the theory and practical use of all kinds of compressors in industrial use from an industry-leading company sourceComplete subject reference and learning resource in one stop, suitable for newly graduated engineers and experienced professional reference useIncludes companion CD-ROM

Download or read book Leakage and Rotordynamic Effects of Pocket Damper Seals and See through Labyrinth Seals written by Ahmed Mohamed Gamal Eldin and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation discusses research on the leakage and rotordynamic characteristics of pocket damper seals (PDS) and see-through labyrinth seals, presents and evaluates models for labyrinth seal and PDS leakage and PDS force coefficients, and compares these seals to other annular gas seals. Low-pressure experimental results are used alongside previously-published high-pressure labyrinth and PDS data to evaluate the models. Effects of major seal design parameters; blade thickness, blade spacing, blade profile, and cavity depth; on seal leakage, as well as the effect of operating a seal in an off-center position, are examined through a series of non-rotating tests. Two reconfigurable seal designs were used, which enabled testing labyrinth seals and PDS with two to six blades. Leakage and pressure measurements were made with air as the working fluid on twenty-two seal configurations. Increasing seal blade thickness reduced leakage by the largest amount. Blade profile results were more equivocal, indicating that both profile and thickness affected leakage, but that the influence of one factor partially negated the influence of the other. Seal leakage increased with increased eccentricity at lower supply pressures, but that this effect was attenuated for higher pressure drops. While cavity depth effects were minor, reducing depths reduced leakage up to a point beyond which leakage increased, indicating that an optimum cavity depth existed. Changing blade spacing produced results almost as significant as those for blade thickness, showing that reducing spacing can detrimentally affect leakage to the point of negating the benefit of inserting additional blades. Tests to determine the effect of PDS partition walls showed that they reduce axial leakage. The pressure drop was found to be highest across the first blade of a seal for low pressure drops, but the pressure drop distribution became parabolic for high pressure drops with the largest drop across the last blade. Thirteen leakage equations made up of a base equations, a flow factor, and a kinetic energy carryover factor were examined. The importance of the carryover coefficient was made evident and a modified carryover coefficient is suggested. Existing fully partitioned PDS models were expanded to accommodate seals of various geometries.

Download or read book Comparison of Experimental and Ideal Leakage Flows Through Labyrinth Seals for Very Small Pressure Differences written by and published by . This book was released on 1970 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Self acting Lift pad Geometry for Circumferential Seals A Noncontacting Concept written by Gordon P. Allen and published by . This book was released on 1980 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Stepped Labyrinth Seal Leakage Performance written by Thomas Stanley Reed and published by . This book was released on 1993 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Labyrinth Seal Analysis Volume 2 User s Manual for the Navier Stokes Analysis for Labyrinth Seals written by and published by . This book was released on 1986 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document is a User's Manual for running a computer code for calculating the flow in labyrinth seals. The computer code has the ability to solve the Navier-Stokes equations for two-dimensional and axisymmetric flow for both orthogonal and non-orthogonal coordinate systems. A description of the code, the strategy for running the code, a detailed description of the input, sample input and sample output are presented. A description of a comparison plot program is also presented. Keywords: Computational fluid mechanics; Leakage flow; Gas turbine engine requirements; Fortran; MINT computer program; PLOT computer program.

Download or read book Proceedings of the 10th International Conference on Rotor Dynamics IFToMM written by Katia Lucchesi Cavalca and published by Springer. This book was released on 2018-08-20 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: IFToMM conferences have a history of success due to the various advances achieved in the field of rotor dynamics over the past three decades. These meetings have since become a leading global event, bringing together specialists from industry and academia to promote the exchange of knowledge, ideas, and information on the latest developments in the dynamics of rotating machinery. The scope of the conference is broad, including e.g. active components and vibration control, balancing, bearings, condition monitoring, dynamic analysis and stability, wind turbines and generators, electromechanical interactions in rotor dynamics and turbochargers. The proceedings are divided into four volumes. This first volume covers the following main topics: Active Components and Vibration Control; Balancing; Bearings: Fluid Film Bearings, Magnetic Bearings, Rolling Bearings and Seals; and Blades, Bladed Systems and Impellers.

Download or read book A Study of Labyrinth Seal Leakage written by Tamara K. Grimmett and published by . This book was released on 1982 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Gas Seal Leakage at High Temperature written by Alain Anderson and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Reducing secondary leakage is a common challenge in numerous machines, particularly in steam and gas turbines. Too large leakage in seals produces a substantial loss in efficiency and power delivery with an increase in specific fuel consumption. Various seal types exist, each with unique advantages and disadvantages as per leakage, power loss, and wear. Labyrinth seals are most common due to their simple design and low cost. Their main drawback is a too high leakage due to enlarged (worn) clearances when a rotor vibrates. More complicated seal types, such as brush seals can withstand rotor excursions and ensure lower leakage rates than with labyrinth seals. Brush seals utilize a bristle bed which contacts the rotor and wears out thereby reducing leakage performance. The HALO[superscript TM] seal, an all-metal seal with flexibly supported shoes, is engineered as a clearance control seal to reduce leakage even more, in particular for operation with high pressure differentials and with high surface rotor speeds. Static leakage tests with hot air at a high temperature (max. 300°C) conducted in a test rig holding a labyrinth seal and a novel all-metal seal (HALO[superscript TM] seal), both of the same diameter, length and clearance, show the novel seal leaks ~1/5 the flow of a labyrinth seal for pressure ratios (P[subscript s]/P[subscript a]) > 3.5. The savings in leakage are maximized during operation at high pressure differentials. Leakage measurements with a rotor spinning to a maximum speed of 2,700 rpm (surface speed = 23.6 m/s) produce a slight decrease in leakage with increasing rotor speed. The research product is a reliable leakage data base enabling the application of a state of the art sealing technology that increases system efficiency by reducing leakage and extends maintenance intervals by eliminating wear of components. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151242