Download or read book STUDY OF LOW REYNOLDS NUMBER EFFECTS ON THE LOSSES IN LOW PRESSURE TURBINE BLADE ROWS NASA written by United States. National Aeronautics and Space Administration and published by . This book was released on 1999* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Low Reynolds Number Effects on the Losses in Low Pressure Turbine Blade Rows written by and published by . This book was released on 1998 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book STUDY OF LOW REYNOLDS NUMBER EFFECTS ON THE LOSSES IN LOW PRESSURE TURBINE BLADE ROWS NASA TM 1998 207919 SEP 16 1998 written by and published by . This book was released on 1999* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reynolds Averaged Navier Stokes Studies of Low Reynolds Number Effects on the Losses in a Low Pressure Turbine written by and published by . This book was released on 1996 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental and Numerical Investigation of Losses in Low Pressure Turbine Blade Rows written by Daniel J. Dorney and published by . This book was released on 2000 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterization of Internal Wake Generator at Low Reynolds Number with a Linear Cascade of Low Pressure Turbine Blades written by Chase A. Nessler and published by . This book was released on 2010 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unsteady flow and its effects on the boundary layer of a low pressure turbine blade is complex in nature. The flow encountered in a low pressure turbine contains unstructured free-stream turbulence, as well as structured periodic perturbations caused by upstream vane row wake shedding. Researchers have shown that these conditions strongly influence turbine blade performance and boundary layer separation, especially at low Reynolds numbers. In order to simulate these realistic engine conditions and to study the effects of periodic unsteadiness, a moving bar wake generator has been designed and characterized for use in the Air Force Research Labs low speed wind tunnel. The layout is similar to other traditional squirrel cage designs, however, the entire wake generator is enclosed inside the wind tunnel, up-stream of a linear cascade. The wake shed from the wake generator was characterized by its momentum deficit, wake width, and peak velocity deficit. It is shown that the wakes produce a periodic unsteadiness that is consistent with other wake generator designs. The effect of the periodic disturbances on turbine blade performance has been investigated at low Reynolds number using the highly loaded, AFRL designed L1A low pressure turbine profile. Wake loss measurements, pressure coefficient distribution, and particle image velocimetry was used to quantify the L1A blade performance with unsteady wakes at a Reynolds number of 25,000 with 0.5% and 3.4% free-stream turbulence. Wake loss data showed that the inclusion of periodic wakes reduced the profile losses by 56% compared to steady flow losses. Previous pressure coefficient distributions showed that the L1A blade profile, under steady flow conditions, has non-reattaching separated flow along the suction surface. With the inclusion of the periodic wakes, the pressure coefficient profile revealed that the flow separation had been dramatically reduced to a small separation bubble. The wake passing event was split into six phases and captured using two-dimensional planer PIV. The interaction between the passing wakes and the separation bubble was noted. The bubble was observed to grow in size between passing wakes, but was only able to achieve a fraction of the original level of separation. The streamlines through the unrestricted blade passage were able to better follow the blade profile, indicating an improved exit flow angle with lower losses. The data shows that the wake generator was successfully implemented into the wind tunnel and is able to properly simulate blade row interactions.
Download or read book An Experimental Investigation of the Aerodynamic Losses for an Incident Tolerant Low Pressure Turbine Blade Over Moderate to Low Reynolds Numbers at Engine Representative Mach Numbers written by Jonathan Adam Long and published by . This book was released on 2015 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of the Effects of Low Reynolds Number Operation on the Performance of a Single Stage Turbine with a Downstream Stator written by Robert E. Forrette and published by . This book was released on 1959 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reduction of Separation Losses on a Turbine Blade with Low Reynolds Number written by James P. Lake and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Dimple Pattern on the Suppression of Boundary Layer Separation on a Low Pressure Turbine Blade written by John P. Casey and published by . This book was released on 2004-03-01 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three dimple patterns were investigated to ascertain their relative effectiveness on controlling boundary layer separation from a low-pressure turbine blade. The three cases included a single row of dimples at 65% of the axial chord with 2.22 cm spacing, a single row of dimples at 65% of the axial chord with 4.44 cm spacing, and a two-row staggered pattern with rows at 65% and 76% of the axial chord with 4.44 cm spacing. The multiple row case was such that the center of the upstream dimple set at the midpoint between two downstream dimples. The dimple spacing was measured center-on-center. Each of the dimple patterns was studied and compared to an unmodified blade at axial chord Reynolds numbers based on inlet velocity of 25k, 45k, and 100k. Experimental data was collected in a low-speed, draw down wind tunnel containing a linear turbine cascade of 8 Pak-B blades. Measurements of surface pressure, boundary layer parameters, wake velocity, and total pressure losses were made to examine the flow. No dimple pattern dramatically outperformed the others. Each of the dimple patterns studied improved the average total pressure loss coefficient by 34% for Re 25k and 1% Tu. Complementing the experimental effort was a three-dimensional computational fluid dynamics study. Four models were built and analyzed. The models included an unmodified blade, blades with dimples at 65% of the axial chord with 2 cm or 4 cm spacing, respectively, and a multiple row case consisting of dimples at 65% and 76% of the axial chord with 2 cm spacing. Again the upstream dimple set at the midpoint between two downstream dimples. The computational fluid dynamics study provided detailed flow visualization in and around the dimples as well as a comparison to experimental data for solver verification. It was shown that the computational and experimental results showed similar trends in wake loss and boundary layer traverses.
Download or read book Numerical Investigation of Low Reynolds Number Flow in Turbine Passage written by Sergio Romero Martinez and published by . This book was released on 2016 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fluid flow across a Low-Pressure Turbine passage has been simulated numerically for a chord-based low Reynolds number of Re = 5,000 and an inlet Mach number of 0.1. Although the practical Reynolds number regime in turbomachinery is considerably larger than 5,000, similarities of the flow topology between the 5,000 and Re = 100,000 flow were attained through boundary layer suction. The present results are for the L2F Low-Pressure Turbine (LPT) profile. This geometry has been developed by the Air Force Research Laboratory (AFRL) for investigating the flow physics of highly loaded LPT blades at low Reynolds numbers. The L2F profile has a front-loaded pressure distribution which attenuates the adverse pressure gradient on the suction surface, thus delaying or preventing separation. Without boundary layer suction the flow separates laminar from the suction surface. With boundary layer suction this separation is almost completely suppressed. Special attention is drawn to the secondary flow effects near the turbine end-wall or hub which are responsible for a large part of the pressure losses in axial jet engines. The two dominant features of the resulting flow topology are the corner flow separation and the passage vortex. Both features are loss mechanisms. Active flow control via harmonic wall-normal blowing or zero-net mass flux control is employed and its effect on the total pressure loss is investigated. The flow control strategies were characterized in terms of the momentum coefficient, c[mu], and the reduced frequency, F+. Remarkable total pressure gains were achieved with zero-net mass flux blowing and suction. The active flow control strategies as discussed here have the potential to increase the efficiency of real LPT stages which operate at higher Reynolds numbers. Any increase in LPT stage performance will result in almost equal overall engine performance gains and thus improve the economics of air travel.
Download or read book International Journal of Turbo Jet engines written by and published by . This book was released on 1998 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the 2011 International Conference on Informatics Cybernetics and Computer Engineering ICCE2011 November 19 20 2011 Melbourne Australia written by Liangzhong Jiang and published by Springer Science & Business Media. This book was released on 2011-11-24 with total page 821 pages. Available in PDF, EPUB and Kindle. Book excerpt: The volume includes a set of selected papers extended and revised from the International Conference on Informatics, Cybernetics, and Computer Engineering. A computer network, often simply referred to as a network, is a collection of computers and devices interconnected by communications channels that facilitate communications and allows sharing of resources and information among interconnected devices. Put more simply, a computer network is a collection of two or more computers linked together for the purposes of sharing information, resources, among other things. Computer networking or Data Communications (Datacom) is the engineering discipline concerned with computer networks. Computer networking is sometimes considered a sub-discipline of electrical engineering, telecommunications, computer science, information technology and/or computer engineering since it relies heavily upon the theoretical and practical application of these scientific and engineering disciplines. Networks may be classified according to a wide variety of characteristics such as medium used to transport the data, communications protocol used, scale, topology, organizational scope, etc. Electronics engineering, also referred to as electronic engineering, is an engineering discipline where non-linear and active electrical components such as electron tubes, and semiconductor devices, especially transistors, diodes and integrated circuits, are utilized to design electronic circuits, devices and systems, typically also including passive electrical components and based on printed circuit boards. The term denotes a broad engineering field that covers important subfields such as analog electronics, digital electronics, consumer electronics, embedded systems and power electronics. Electronics engineering deals with implementation of applications, principles and algorithms developed within many related fields, for example solid-state physics, radio engineering, telecommunications, control systems, signal processing, systems engineering, computer engineering, instrumentation engineering, electric power control, robotics, and many others. ICCE 2011 Volume 3 is to provide a forum for researchers, educators, engineers, and government officials involved in the general areas of Computer Engineering and Electronic Engineering to disseminate their latest research results and exchange views on the future research directions of these fields. 99 high-quality papers are included in the volume. Each paper has been peer-reviewed by at least 2 program committee members and selected by the volume editor. Special thanks to editors, staff of association and every participants of the conference. It’s you make the conference a success. We look forward to meeting you next year.
Download or read book Use of Dimples to Suppress Boundary Layer Separation on a Low Pressure Turbine Blade written by Kurt P. Rouser and published by . This book was released on 2002-12-01 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow separation on a low pressure turbine blade is explored at Reynolds numbers of 25k, 45k and 100k, Experimental data is collected in a low- speed, draw-down wind tunnel using a cascade of eight Pak-B blades, Flow is examined from measurements of blade surface pressures, boundary layer parameters, exit velocities, and total pressure losses across the blade, Two recessed dimple shapes are assessed for suppressing flow separation and associated losses, One dimple is spherical, and the second is asymmetric, formed from a full dimple spanwise half-filled, A single row of each dimple shape is tested at 50%, 55% and 65% axial chord, Symmetric dimples reduce separation losses by as much as 28%, while asymmetric dimples reduce losses by as much as 23%, A complementary three-dimensional computational study is conducted to visualize local flow structure, Computational analysis uses Gridgen v13,3 as a mesh generator, Fluent v6,O as a flow solver and FIELDVIEW - v8,0 for graphic display and analysis, Computational results for Pak-B blades at a Reynolds number of 25k indicate that both dimple shapes cause a span-wise vortex to rollup within the dimple and provide a localized pressure drop,
Download or read book On the Experimental Evaluation of Loss Production and Reduction in a Highly Loaded Low Pressure Turbine Cascade written by Philip Steven Bear and published by . This book was released on 2016 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Improvements in turbine design methods have resulted in the development of blade profiles with both high lift and good Reynolds lapse characteristics. An increase in aerodynamic loading of blades in the low pressure turbine section of aircraft gas turbine engines has the potential to reduce engine weight or increase power extraction. Increased blade loading means larger pressure gradients and increased secondary losses near the endwall. Prior work has emphasized the importance of reducing these losses if highly loaded blades are to be utilized. The present study analyzes the secondary flow field of the front-loaded low-pressure turbine blade designated L2F with and without blade profile contouring at the junction of the blade and endwall. The current work explores the loss production mechanisms inside the low pressure turbine cascade. Stereoscopic particle image velocimetry data, total pressure loss data and oil flow visualization are used to describe the secondary flow field. The flow is analyzed in terms of total pressure loss, vorticity, Q-Criterion, Reynolds' stresses, turbulence intensity and turbulence production. The flow description is then expanded upon using an Implicit Large Eddy Simulation of the flow field. The RANS momentum equations contain terms with static pressure derivatives. With some manipulation these equations can be rearranged to form an equation for the change in total pressure along a streamline as a function of velocity only. After simplifying for the flow field in question the equation can be interpreted as the total pressure transport along a streamline. A comparison of the total pressure transport calculated from the velocity components and the total pressure loss is presented and discussed. Peak values of total pressure transport overlap peak values of total pressure loss through and downstream of the passage suggesting that total pressure transport is a useful tool for localizing and predicting loss origins and loss development using velocity data which can be obtained non-intrusively.
Download or read book Low Reynolds Number Loss Reduction on Turbine Blades with Dimples and V grooves written by James P. Lake and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Impingement Jet Cooling in Gas Turbines written by R.S. Amano and published by WIT Press. This book was released on 2014-05-28 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the requirement for enhanced cooling technologies on modern gas turbine engines, advanced research and development has had to take place in field of thermal engineering. Among the gas turbine cooling technologies, impingement jet cooling is one of the most effective in terms of cooling effectiveness, manufacturability and cost. The chapters contained in this book describe research on state-of-the-art and advanced cooling technologies that have been developed, or that are being researched, with a variety of approaches from theoretical, experimental, and CFD studies. The authors of the chapters have been selected from some of the most active researchers and scientists on the subject. This is the first to book published on the topics of gas turbines and heat transfer to focus on impingement cooling alone.
