Download or read book Unsteady Flows in a Two dimensional Linear Cascade with Low pressure Turbine Blades written by Christopher G. Murawski and published by . This book was released on 1999 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Three dimensional Unsteady Flow in Oscillating Turbine Blade Row written by and published by . This book was released on 2006 with total page 173 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 High order Accurate Solution for Flow Through a Turbine Linear Cascade written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Low-pressure turbines (LPT) in aircraft engines undergo tremendous losses at cruise conditions. The flow Reynolds number at cruise is lower than the take-off Reynolds number by a factor of almost two. At low Reynolds numbers, the flow is largely laminar, and tends to separate easily on the suction surface of the turbine blade when an adverse pressure gradient is encountered. Therefore, accurate prediction of flow separation is crucial for an effective design of LPT blade; and is achieved in the present work using a high-order accurate numerical solution procedure. The three-dimensional, unsteady, full Navier-Stokes equations are solved to analyze the flow. A MPI-based higher-order, parallel, chimera version of the FDL3DI flow solver, is extended for use with this turbomachinery application. A sixth-order accurate compact-difference scheme is used for the spatial discretization, along with second-order accurate temporal discretization. Tenth-order filtering is used to minimize the numerical oscillations in the flow solution and maintain numerical stability. The objective of the present study is to show the ability of higher-order accurate compact-difference scheme to predict the flow separation that occurs inside an LPT cascade at Re C = 25,000 (based on axial chord and inlet velocity). A new set of subsonic inflow/outflow boundary conditions that account for upstream influence (BC2) are derived by specifying stagnation quantities at the inlet, and a static quantity at the exit of the flow domain, and maintaining the inflow angle constant. For inflow/outflow boundary conditions that do not account for upstream influence, fixed inflow with extrapolated outflow (BC1) has been utilized. The effect of the two different sets of inflow/outflow boundary conditions on the flow solution is studied, for second-order, fourth-order and sixth-order accurate schemes. The computed Cp distribution for the LPT flow shows good agreement with the existing experimental data. The location of the onset of separation matches with an available LES simulation result and with the available experimental data. The performance of high-order compact difference schemes has been assessed via simulation of laminar flow over a circular cylinder at Re D = 250 (based on free-stream velocity and cylinder diameter). The sixth-order accurate compact difference scheme with tenth-order filtering on a coarser mesh preserves the vortex structure better than possible with the second-order accurate scheme on a finer mesh. This demonstrates the efficiency of the higher-order accurate compact difference scheme.
Download or read book Analysis of Unsteady Secondary Flows in Linear Low pressure Turbine Cascades written by Roberto Ciorciari and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Unsteady Aerodynamics Aeroacoustics and Aeroelasticity of Turbomachines and Propellers written by H.M. Atassi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 876 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first International Symposium on Unsteady Aerodynamics and Aero elasticity of Turbomachines was held in Paris in 1976, and was followed by symposia at Lausanne in 1980, Cambridge in 1984, Aachen in 1987, Bei jing in 1989, and Notre Dame in 1991. The proceedings published following these symposia have become recognized both as basic reference texts in the subject area and as useful guides to progress in the field. It is hoped that this volume, which represents the proceedings of the Sixth International Symposium on Unsteady Aerodynamics of Turbomachines, will continue that tradition. Interest in the unsteady aerodynamics, aeroacoustics, and aeroelasticity of turbomachines has been growing rapidly since the Paris symposium. This expanded interest is reflected by a significant increase in the numbers of contributed papers and symposium participants. The timeliness of the topics has always been an essential objective of these symposia. Another important objective is to promote an international exchange between scien tists and engineers from universities, government agencies, and industry on the fascinating phenomena of unsteady turbomachine flows and how they affect the aeroelastic stability of the blading system and cause the radiation of unwanted noise. This exchange acts as a catalyst for the development of new analytical and numerical models along with carefully designed ex periments to help understand the behavior of such systems and to develop predictive tools for engineering applications.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1972 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Science Technology and the Modern Navy written by Edward I. Salkovitz and published by . This book was released on 1976 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aeronautical Engineering written by and published by . This book was released on 1991 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 41st AIAA Aerospace Sciences Meeting Exhibit written by and published by . This book was released on 2003 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational Fluid Dynamics Review 1998 In 2 Volumes written by Mohamed M Hafez and published by World Scientific. This book was released on 1998-11-20 with total page 1169 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first volume of CFD Review was published in 1995. The purpose of this new publication is to present comprehensive surveys and review articles which provide up-to-date information about recent progress in computational fluid dynamics, on a regular basis. Because of the multidisciplinary nature of CFD, it is difficult to cope with all the important developments in related areas. There are at least ten regular international conferences dealing with different aspects of CFD.It is a real challenge to keep up with all these activities and to be aware of essential and fundamental contributions in these areas. It is hoped that CFD Review will help in this regard by covering the state-of-the-art in this field.The present book contains sixty-two articles written by authors from the US, Europe, Japan and China, covering the main aspects of CFD. There are five sections: general topics, numerical methods, flow physics, interdisciplinary applications, parallel computation and flow visualization. The section on numerical methods includes grids, schemes and solvers, while that on flow physics includes incompressible and compressible flows, hypersonics and gas kinetics as well as transition and turbulence. This book should be useful to all researchers in this fast-developing field.
Download or read book On the Physics of Flow Separation Along a Low Pressure Turbine Blade Under Unsteady Flow Conditions written by and published by . This book was released on 2003 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Air Breathing Engines and Aerospace Propulsion written by B. N. Raghunandan and published by Allied Publishers. This book was released on 2004 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contributed papers presented at the 7th National Conference on Air Breathing Engines and Aerospace Propulsion, hosted at I.I.T., Kanpur.
Download or read book Unsteady Aerodynamics Aeroacoustics and Aeroelasticity of Turbomachines written by Kenneth C. Hall and published by Springer Science & Business Media. This book was released on 2006-05-11 with total page 605 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook is a collection of technical papers that were presented at the 10th International Symposium on Unsteady Aerodynamics, Aeroacoustics, and Aeroelasticity of Turbomachines held September 8-11, 2003 at Duke University in Durham, North Carolina. The papers represent the latest in state of the art research in the areas of aeroacoustics, aerothermodynamics, computational methods, experimental testing related to flow instabilities, flutter, forced response, multistage, and rotor-stator effects for turbomachinery.
Download or read book Paper written by and published by . This book was released on 2001 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book CFD Simulations for the Effect of Unsteady Wakes on the Boundary Layer of a Highly Loaded Low Pressure Turbine Airfoil L1A written by Samuel J. Vinci and published by . This book was released on 2011 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of a very high lift, low-pressure turbine airfoil in the presence of unsteady wakes was performed computationally and compared against experimental results. The experimental data were collected in a low speed wind tunnel under high (4.9%) and then low (0.6%) freestream turbulence intensity conditions on a linear cascade with wakes that were produced from moving rods upstream of the cascade. The flow coefficient was kept at 0.7 while the rod to blade spacing was changed from 1 to 1.6 to 2 blade spacings. These cases were conducted for Reynolds number equal to 25,000 and 50,000, based on the suction surface length and the nominal exit velocity from the cascade. The experimental and computational data have shown that in cases without wakes, the boundary layer separated and did not reattach. The CFD was done with LES and URANS utilizing the finite-volume code ANSYS Fluent under the same freestream turbulence and Reynolds number conditions as the experiment but only at a rod to blade spacing of 1. With wakes, separation was largely suppressed, particularly if the wake passing frequency was sufficiently high. This was validated in the CFD by comparing the experimental results for the pressure coefficients and velocity profiles, which were reasonable for all cases examined, showing very consistent results in a three dimensional domain with a larger Reynolds' number. The two dimensional domain failed to capture the three dimensionality effects of the wake and thus were less consistent with the experimental data. The effect of the freestream turbulence intensity levels also showed a little more consistency with the experimental data at higher intensities; however the low intensity results were also very consistent. As a further computational study, cases were run to simulate a higher wake passing frequencies which were not run experimentally. The results of these computational cases showed that an initial 25% increase in the wake passing frequency greatly reduced the size of the separation bubble, nearly completely suppressing it; however an additional 33% increase on top of this did not prove to have much of an effect.
