Download or read book Exploratory Investigation for Reducing Labyrinth Seal Leakage in High Pressure Ratio Gas Turbines written by H. L. Stocker and published by . This book was released on 1973 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: The attendant problem of labyrinth seal air leakage in current and advanced high pressure ratio gas turbines is directly related to the limitations of current gas turbine dynamic seal technology. A method of improving the efficiency of labyrinth seals which does not violate mechanical design constraints involves increasing the internal cavity turbulence of the seal. Therefore, an exploratory investigation was undertaken to conceive, design, fabricate, and test several unique labyrinth seal configurations. (Modified author abstract).

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 652 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

Download or read book Continued Investigation of Leakage and Power Loss Test Results for Competing Turbine Engine Seals written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-24 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Secondary seal leakage in jet engine applications results in power losses to the engine cycle. Likewise, seal power loss in jet engines not only result in efficiency loss but also increase the heat input into the engine resulting in reduced component lives. Experimental work on labyrinth and annular seals was performed at NASA Glenn Research Center to quantify seal leakage and power loss at various temperatures, seal pressure differentials, and surface speeds. Data from annular and labyrinth seals are compared with previous brush and finger seal test results. Data are also compared to literature. Annular and labyrinth seal leakage rates are 2 to 3 times greater than brush and finger seal rates. Seal leakage decreases with increasing speed but increases with increasing test temperature due to thermal expansion mismatch. Also seal power loss increases with surface speed, seal pressure differential, mass flow rate, and radial clearance. Annular and labyrinth seal power losses were higher than those of brush or finger seal data. The brush seal power loss was 15 to 30 percent lower than annular and labyrinth seal power loss. Delgado, Irebert R. and Proctor, Margaret P. Glenn Research Center NASA/TM-2006-214420, ARL-MR-0643, AIAA Paper 2006-4754, E-15638

Download or read book Leakage and Power Loss Test Results for Competing Turbine Engine Seals written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-21 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced brush and finger seal technologies offer reduced leakage rates over conventional labyrinth seals used in gas turbine engines. To address engine manufacturers concerns about the heat generation and power loss from these contacting seals, brush, finger, and labyrinth seals were tested in the NASA High Speed, High Temperature Turbine Seal Test Rig. Leakage and power loss test results are compared for these competing seals for operating conditions up to 922 K (1200 F) inlet air temperature, 517 KPa (75 psid) across the seal, and surface velocities up to 366 m/s (1200 ft/s). Proctor, Margaret P. and Delgado, Irebert R. Glenn Research Center NASA/TM-2004-213049, GT2004-53935, E-14452

Download or read book Leakage and Power Loss Test Results for Competing Turbine Engine Seals written by and published by . This book was released on 2004 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced brush and finger seal technologies offer reduced leakage rates over conventional labyrinth seals used in gas turbine engines. To address engine manufacturers' concerns about the heat generation and power loss from these contacting seals, brush, finger, and labyrinth seals were tested in the NASA High Speed, High Temperature Turbine Seal Test Rig. Leakage and power loss test results are compared for these competing seals for operating conditions up to 922 K (1200 degrees F) inlet air temperature, 517 KPa (75 psid) across the seal, and surface velocities up to 366 m/s (1200 ft/s).

Download or read book Aerodynamic Performance of Conventional and Advanced Design Labyrinth Seals with Solid smooth Abradable and Honeycomb Lands written by and published by . This book was released on 1977 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Power Dissipation in Smooth and Honeycomb Labyrinth Seals written by and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The surface frictional characteristics of a labyrinth seal can result in significant windage power dissipation for high speed seals. Recent advances in seal design have produced high speed, high pressure labyrinth seals which operate at very low leakage rates. The reduced leakage is beneficial to gas turbine efficiency, but seal discharge temperatures can approach material design limits with high windage power dissipation. Also, a high air temperature rise can influence seal leakage flow. Consequently, the general assumption of negligible rotational effect on leakage is not always valid. A method is presented for the prediction of seal power dissipation and leakage flow over a wide range of design parameters. Results are compared to available test data and several approaches examined for the reduction of seal windage.

Download or read book Effects of Operating Damage of Labyrinth Seal on Seal Leakage and Wheelspace Hot Gas Ingress written by Jinming Xu and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The labyrinth seal is widely used in turbomachinery to minimize or control leakage between areas of different pressure. The present investigation numerically explored the effect of damage and wear of the labyrinth seal on the turbomachinery flow and temperature fields. Specifically, this work investigated: (1) the effect of rubgroove downstream wall angle on seal leakage, (2) the effect of tooth bending damage on the leakage, (3) the effect of tooth "mushrooming" damage on seal leakage, and (4) the effect of rub-groove axial position and wall angle on gas turbine ingress heating. To facilitate grid generation, an unstructured grid generator named OpenCFD was also developed. The grid generator is written in C++ and generates hybrid grids consisting primarily of Cartesian cells. This investigation of labyrinth seal damage and wear was conducted using the Reynolds averaged Navier-Stokes equations (RANS) to simulate the flows. The high- Reynolds k - e Model and the standard wall function were used to model the turbulence. STAR-CD was used to solve the equations, and the grids were generated using the new code OpenCFD. It was found that the damage and wear of the labyrinth seal have a significant effect on the leakage and temperature field, as well as on the flow pattern. The leakage increases significantly faster than the operating clearance increase from the wear. Further, the specific seal configuration resulting from the damage and wear was found to be important. For example, for pure-bending cases, it was found that the bending curvature and the percentage of tooth length that is bent are important, and that the mushroom radius and tooth bending are important for the mushrooming damage cases. When an abradable labyrinth seal was applied to a very large gas turbine wheelspace cavity, it was found that the rub-groove axial position, and to a smaller degree, rub-groove wall angle, alter the magnitude and distribution of the fluid temperature.

Download or read book Pressure Balanced Low Hysteresis Finger Seal Test Results written by Gul K. Arora and published by . This book was released on 1999 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The finger seal is a revolutionary new technology in air to air sealing for secondary flow control and gas path sealing in gas turbine engines. Though the seal has been developed for gas turbines, it can be easily used in any machinery where a high pressure air cavity has to be sealed from a low pressure air cavity, for both static and rotating applications. This seal has demonstrated air leakage considerably less than a conventional labyrinth seal and costs considerably less than a brush seal. A low hysteresis finger seal design was successfully developed and tested in a seal rig at NASA Glenn Research Center. A total of thirteen configurations were tested to achieve the low hysteresis design. The best design is a pressure balanced finger seal with higher stiffness fingers. The low hysteresis seal design has undergone extensive rig testing to assess its hysteresis, leakage performance and life capabilities. The hysteresis, performance and endurance test results are presented. Based on this extensive testing, it is determined that the finger seal is ready for testing in an engine.

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 Shaft Seals for Compressors and Turbines for Gas cooled Reactor Application written by Oak Ridge National Laboratory and published by . This book was released on 1959 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Announcements written by and published by . This book was released on 1974 with total page 826 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 Frederick C. Yeh and published by . This book was released on 1970 with total page 48 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 High Temperature Leakage Performance of a Hybrid Brush Seal Compared to a Standard Brush Seal and a Labyrinth Seal written by Zachary Ashton and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Adequate sealing in turbomachinery reduces secondary leakage and results in more efficient and stable systems. Labyrinth seals are most common, although brush seals are popular in specialized applications. The Hybrid Brush Seal (HBS) is a novel design that adds to the bristle brush matrix a number of cantilever pads that rest on the rotor surface. Upon shaft rotation the pads lift due to the generation of a hydrodynamic gas film while the brushes effectively seal an upstream pressure. Hence the HBS has no wear and no local thermal distortion effects. Measurements of leakage versus pressure differential are obtained in a three-teeth labyrinth, a conventional brush seal, and a hybrid brush seal for operation at high temperature (300o.C), with shaft surface speeds to 27 m/s, and at supply pressures to 3.5 bar. Flow measurements are presented in terms of a flow factor to remove dependency on the air temperature and supply pressure. The measurements demonstrate the HBS leaks less (~61%) than a standard brush seal and is significantly better (~38%) than a similarly sized labyrinth seal. Predictions of flow through a labyrinth seal predict well at supply pressures under 1.7 bar but overpredict by as much as 25% at high supply pressures. A porous medium fluid flow model predicts the flow through the HBS and brush seal. The model for the HBS and brush seal underpredicts the flow rate at low supply pressures but match well at high supply pressures. Measurements of the drag torque of the test seals show the HBS has a larger torque when pressurized compared to the brush seal and labyrinth seal. This indicates that the HBS experiences a larger degree of blow-down due to the pads decreasing the clearance. The mechanical parameters of the brush seal and HBS are found based upon the flexibility function from impact load tests. A combined structural and dry friction damping model represent well the measured flexibility. An equivalent damping is found based upon the energy dissipation. Based upon the damping ratio, the HBS has twice of the viscous damping as the brush seal at a supply pressure of 2.0 bar.

Download or read book Government Reports Index written by and published by . This book was released on 1975 with total page 908 pages. Available in PDF, EPUB and Kindle. Book excerpt: