Download or read book Leakage Estimation of Incompressible Fluids in Stepped Labyrinth Seals with Swirl written by Scott Perry Waughtal and published by . This book was released on 1986 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Leakage Estimation of Incompressible Fluids in Stepped Labyrinth Seals written by Daesung Chi and published by . This book was released on 1983 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fluid Mechanics Model to Estimate the Leakage of Incompressible Fluids Through Labyrinth Seals LMFBR written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An analytical model for estimating the leakage of incompressible fluids through straight labyrinth seals has been described. Recent developments in theoretical and experimental studies of recirculating flow inside rectangular cavities and of flow in a channel have been incorporated in the model to solve a practical problem. The approach used in this model is different from those of previous ones for compressible fluids in which the gas-dynamics laws with some empirical coefficients determined from gas data were used. The seal leakages predicted by the model are in reasonable agreement with these measured indirectly in sodium and those obtained for gas at low Mach number and small pressure variations. It can be concluded from this study that the labyrinth seal formed with cavities has less leakage than the one formed with threads if all other conditions are the same. Furthermore, the fluid leakage through straight labyrinth seals (for both cavity and thread types) is strongly dependent upon the seal clearance and pressure drop.

Download or read book A Fluid Mechanics Model to Estimate the Leakage of Incompressible Fluids Through Labyrinth Seals written by J. T. Han and published by . This book was released on 1979 with total page 8 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 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 Leakage Prediction of Incompressible Fluids in Labyrinth Seals written by Kevin Charles Cogan and published by . This book was released on 1982 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 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 The Prediction and Measurement of Incompressible Flow in a Labyrinth Seal written by Jonathan Alexander Demko and published by . This book was released on 1986 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow Visualization and Leakage Measurments of Stepped Labyrinth Seals Part 2 Sloping Surfaces written by David L. Rhode and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented at the International Gas Turbine and Aeroengine Congress &Exhibition Birmingham, UK - June 10-13, 1996.

Download or read book Flow Visualization and Leakage Measurments of Stepped Labyrinth Seals Part 1 Annular Groove written by David L. Rhode and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented at the International Gas Turbine and Aeroengine Congress &Exhibition Birmingham, UK - June 10-13, 1996.

Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) * at Purdue University in 1 957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all con cerned if the printing and distribution of the volumes were handled by an interna tional publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Cor poration of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 28 (thesis year 1 983) a total of 10,661 theses titles from 26 Canadian and 197 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this important annual reference work. While Volume 28 reports theses submitted in-1983, on occasion, certain univer sities do report theses submitted in previous years but not reported at the time.

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 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 The Effect of High Rotational Speed on the Performance of Straight through Labyrinth Seals for Compressible and Incompressible Flow written by Ekene R. Obidigbo and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The leakage flow through straight through labyrinth seals with tooth on stator was investigated by performing CFD simulations .ANSYS Fluent is used to simulate the fluid flow through straight through Labyrinth seals. The effect of seal geometry on discharge coefficient, carry over coefficient and expansion factor is studied by varying clearance, pitch, tooth height, tooth width, Reynolds number and rotor speed. Derived quantities Such as carry over coefficient, coefficient of discharge and expansion factor are analyzed as a function of the tooth with preceding cavity to predict the effectiveness of the seal. To understand the effect of varying seal geometries and swirl, 2D CFD simulations were performed. It was found that the clearance to pitch ratio is a strong geometry factor which affect the performance of the seal. The carryover coefficient which describes the portion of kinetic energy carried over from one cavity to the next is also examined. It was found to be a function of Reynolds number and shaft speed. Discharge coefficient describes the losses which occur when fluid flows through the cavity and under the tooth. Just like the carryover coefficient, it is also discovered that it is a strong function of Reynolds number and shaft speed.