Download or read book Turbine Tip Clearance Loss Mechanisms written by Steven Andrew Mazur and published by . This book was released on 2013 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three-dimensional numerical simulations (RANS and URANS) were used to assess the impact of two specific design features, and of aspects of the actual turbine environment, on turbine blade tip loss. The calculations were carried out for a subsonic high pressure turbine stage. The loss mechanism examined is that due to tip clearance vortex mixing. The effects examined were three-dimensional blade stacking, downstream transition duct geometry, and unsteadiness due to an upstream nozzle guide vane. Tip leakage loss changes due to three-dimensional blade stacking (bowing or reverse bowing) are verified to be associated with changes in the magnitude of blade tip loading, which create differences in the leakage flow exit velocities. The effect of a downstream diffusing transition duct on tip leakage losses is small; there was a 3.6% increase in tip leakage loss for a 65% increase in duct exit-to-inlet area ratio compared to a constant area duct. For unsteadiness arising from an upstream nozzle guide vane, it is shown that substantial temporal fluctuations in vortex core velocity and loss generation exist. However, the time average tip leakage loss differed less than 5% from the tip leakage loss calculated on a steady flow basis. Based on the computations, the mechanism for tip leakage vortex loss in the three different situations examined appears to be similar to that which is seen for an isolated turbine blade.
Download or read book Loss Mechanisms in Turbine Tip Clearance Flows written by Arthur C. Huang and published by . This book was released on 2011 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical simulations of tip clearance ow have been carried out to dene the loss generation mechanisms associated with tip leakage in unshrouded axial turbines. Mix- ing loss between the leakage, which takes the form of a strong embedded streamwise vortex (u=ux 1 in the vortex core), and the mainstream ow is found to be the main source of loss. Vortex line contraction, and consequent vortex core expansion, and also vortex breakdown, are identied as the two important mechanisms that determine mixing loss. Because of these vortex dynamic features, the behavior is dierent from the conventional view of the effect of pressure level on mixing of non- uniform flows. More specifically, it is shown, through control volume arguments and axisymmetric computations, that as a strongly swirling ow passes through a pres- sure rise, the mixed-out loss can either decrease or increase, the latter occurring if the deceleration becomes large enough to initiate vortex breakdown. It is further shown that tip vortices in turbines experience pressure rises large enough to cause vortex breakdown. The effect of pressure distribution on tip leakage losses is illustrated through examination of two turbine blades, one designed with a forward loaded tip and one with an aft loaded tip. The computations show a 16% difference in tip clearance loss between the two, due to the lower pressure rise encountered by the clearance vortex, and hence lower vortex breakdown losses, with the forward loaded blade. Other computational experiments, on the effects of blade loading, incidence, and solidity, are also shown to be consistent with the ideas developed about blade pressure distribution effects on vortex breakdown and hence clearance mixing loss.
Download or read book Endwall Flow loss Mechanisms in a Linear Turbine Cascade with Blade Tip clearance written by A. Yamamoto and published by . This book was released on 1988 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanisms of Endwall leakage Flows and the Associated Losses in a Linear Turbine Rotor Cascade with Blade Tip clearance written by Atsumasa Yamamoto and published by . This book was released on 1988 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Internal Flow written by E. M. Greitzer and published by Cambridge University Press. This book was released on 2007-02-26 with total page 739 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the analysis and behaviour of internal flows encountered in propulsion systems, fluid machinery (compressors, turbines and pumps) and ducts (diffusers, nozzles and combustion chambers). The focus is on phenomena that are important in setting the performance of a broad range of fluid devices. The authors show that even for complex processes one can learn a great deal about the behaviour of such devices from a clear understanding and rigorous use of basic principles. Throughout the book they illustrate theoretical principles by reference to technological applications. The strong emphasis on fundamentals, however, means that the ideas presented can be applied beyond internal flow to other types of fluid motion. The book equips students and practising engineers with a range of new analytical tools. These tools offer enhanced interpretation and application of both experimental measurements and the computational procedures that characterize modern fluids engineering.
Download or read book Radial Flow Turbocompressors written by Michael Casey and published by Cambridge University Press. This book was released on 2021-06-10 with total page 789 pages. Available in PDF, EPUB and Kindle. Book excerpt: An introduction to the theory and engineering practice that underpins the component design and analysis of radial flow turbocompressors. Drawing upon an extensive theoretical background and years of practical experience, the authors provide descriptions of applications, concepts, component design, analysis tools, performance maps, flow stability, and structural integrity, with illustrative examples. Features wide coverage of all types of radial compressor over many applications unified by the consistent use of dimensional analysis. Discusses the methods needed to analyse the performance, flow, and mechanical integrity that underpin the design of efficient centrifugal compressors with good flow range and stability. Includes explanation of the design of all radial compressor components, including inlet guide vanes, impellers, diffusers, volutes, return channels, de-swirl vanes and side-streams. Suitable as a reference for advanced students of turbomachinery, and a perfect tool for practising mechanical and aerospace engineers already within the field and those just entering it.
Download or read book A Computational Study of Tip Leakage Flow and Losses in a Linear Turbine Cascade written by Joan G. Moore and published by . This book was released on 1992 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: A computational study of 3-D flow in the VPI and SU tip leakage turbine cascade is used to show the level of modelling attainable now. Results for the overall flow development are compared with measurements of flow and losses at the exit of the tip leakage gap and downstream of the blade row. Mechanisms for the additional loss due to tip leakage are discussed. Consideration is given to areas where the modelling of fine scale flow structure may be improved. These include the flow in the tip clearance gap, flow in the tip leakage vortex, and flow separation at the trailing edge.
Download or read book Effect of Rotor Tip Clearance on the Performance of a 5 inch Single Stage Axial Flow Turbine written by Donald E. Holeski and published by . This book was released on 1969 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbomachinery Fluid Dynamics and Heat Transfer written by Hah and published by Routledge. This book was released on 2017-10-02 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: This festschrift in honor of Professor Budugur Lakshminarayana's 60th birthday-based on the proceedings of a symposium on Turbomachinery Fluid Dynamics and Heat Transfer held recently at The Pennsylvania State University, University Park-provides authoritative and conclusive research results as well as new insights into complex flow features found in the turbomachinery used for propulsion, power, and industrial applications. Explaining in detail compressors, heat transfer fields in turbines, computational fluid dynamics, and unsteady flows, Turbomachinery Fluid Dynamics and Heat Transfer covers: Mixing mechanisms, annulus wall boundary layers, and the flow field in transonic turbocompressors The numerical implementation of turbulence models in a computer code Secondary flows, film cooling, and thermal turbulence modeling The visualization method of modeling using liquid crystals Innovative techniques in the computational modeling of compressor and turbine flows measurement in unsteady flows as well as axial flows and compressor noise generation And much more Generously illustrated and containing key bibliographic citations, Turbomachinery Fluid Dynamics and Heat Transfer is an indispensable resource for mechanical, design, aerospace, marine, manufacturing, materials, industrial, and reliability engineers; and upper-level undergraduate and graduate students in these disciplines.
Download or read book Analysis of Turbine Rotor Tip Clearance Losses and Parametric Optimization of Shroud written by William V. Banks (III) and published by . This book was released on 2019 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerodynamic losses due to tip leakage in a High Pressure Turbine (HPT) rotor setting are analyzed using the commercial CFD software Star-CCM+. The compressible RANS equations were solved over unstructured polyhedral grids of 11 to 17 million cells, with turbulence resolved using the k-w SST model. A study of 3 blade tip/casing configurations at tip clearances between 0% and 4% of blade span is performed, with resulting mass-flow Reynolds #'s of 2.4-2.7 million and levels of reaction of 0.13-0.17. A flat-tip blade experienced a linear correlation between tip clearance and efficiency. The same blade with recessed casing was more efficient for small clearances, but large shear losses were seen to nullify this advantage at high clearances. A shrouded blade was more efficient than both at all clearances, displaying asymptotic behavior at high clearances. Various pressure and velocity monitoring techniques are employed to evaluate leakage flow and loss. Location and strength of leakage vortices are discussed, as these are closely tied with efficiency. A parametric study was performed on the shroud geometry, examining seal angle, number of seals, seal wear, and shroud axial gap. Efficiencies were compared between each study point at clearances of 2% and 4% of blade span. Total pressure loss was tracked across the blade and split between the main flow path and tip gap to distinguish between Profile and Internal Gap Shear losses. Axial gap was seen to have the greatest impact on efficiency, as a narrower gap acts as additional tip flow blockage and increases efficiency. At lower clearances, seal wear produced a negative impact as well.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 488 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 Turbine Inlet Non uniformities and Unsteady Mechanisms written by Devon James Jedamski and published by . This book was released on 2015 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of axial turbine stage inlet non-uniformities are examined through two model problems: wake attenuation and hot streak processing. In the first, twodimensional calculations (RANS and URANS) are used to identify the mechanisms contributing to upstream stator wake attenuation through a turbine blade row. For a representative turbine rotor, pitch and time-averaged wake attenuation by 74% percent is demonstrated at one quarter chord downstream of the trailing edge. Near the pressure surface, the wake stagnation pressure increases by up to 42% above the freestream stagnation pressure. The mechanisms identified are a localized reduction in flow-through time for wake fluid near the pressure surface, compared to the freestream, and an unsteady pressure field (Op/&t) in the rotor reference frame that increases work extraction in the freestream relative to wake fluid. For the second model problem, three-dimensional calculations (RANS and URANS) identify a difference in turbine efficiency sensitivity to thermal distortion between a geometry with no tip gap and a geometry with a finite tip gap. The turbine with a tip clearance is 2.5 times less sensitive, in terms of efficiency decrease, to an inlet hot streak. For the tip gap and no tip gap geometries, the efficiency drops by 0.75% and 1.86% respectively for a peak temperature non-uniformity equal to 0.6 times the combustor temperature rise. The difference in efficiency decrease, due to hot streak, between the two geometries is linked to a reduction in tip leakage mixing losses caused by changes in relative rotor inlet flow angle with and without hot streak.
Download or read book Gas Turbines for Electric Power Generation written by S. Can Gülen and published by Cambridge University Press. This book was released on 2019-02-14 with total page 735 pages. Available in PDF, EPUB and Kindle. Book excerpt: Everything you wanted to know about industrial gas turbines for electric power generation in one source with hard-to-find, hands-on technical information.
Download or read book The Development of Axial Turbine Leakage Loss for Two Profiled Tip Geometries Using Linear Cascade Data written by George Morphis and published by . This book was released on 1990 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: To assess the possibility of tip clearance loss reduction and to explore the nature and origin of tip clearance loss, blade tip geometries that reduce the roughly 40 percent of total loss occurring within the gap were studied. The shapes investigated aimed at reducing or avoiding the gap separation bubble thought to contribute significantly to both internal gap loss and to the endwall mixing loss. It was found that radiusing and contouring the blade at gap inlet eliminated the separation bubble and reduced the internal gap loss but created a higher mixing loss to give almost unchanged overall loss coefficients when compared with the simple sharp-edged flat-tipped blade. The separation bubble does not therefore appear to influence the mixing loss. Using a method of assessing linear cascade experimental data as though it were a rotor with work transfer, one radiused geometry, contoured to shed radial flow into the gap and reduce the leakage mass flow, was found to have a significantly higher efficiency. This demonstrates the effectiveness of the data analysis method and that cascade loss coefficient alone or gap discharge coefficient cannot be used to evaluate tip clearance performance accurately. Contouring may ultimately lead to better rotor blade performances.
Download or read book The Aerothermodynamics of Aircraft Gas Turbine Engines written by and published by . This book was released on 1978 with total page 770 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Feasibility Study for a Practical High Rotor Tip Clearance Turbine written by Dennis C. Evans and published by . This book was released on 1972 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbine tip clearance loss prediction methods were investigated analytically. Vector diagram variations, flow path wall curvature, and stator tangential lean and axial sweep affect the magnitude of this loss for given turbine design requirements and tip clearance. For a model core turbine, a potential 30% reduction in clearance loss relative to an equivalent free vortex turbine is predicted for a practical application of these variations. A follow-on investigation is proposed. (Author).
Download or read book NASA Technical Paper written by and published by . This book was released on 1984 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt:
