Download or read book UNSFLO a Numerical Method for the Calculation of Unsteady Flow in Turbomachinery written by Massachusetts Institute of Technology. Gas Turbine Laboratory and published by . This book was released on 1991 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book UNSFLO written by Michael Giles and published by . This book was released on 1991 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book UNSFLO written by Michael Giles and published by . This book was released on 1988 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction: There are four principal sources of unsteadiness in a single stage of a turbomachine in which there is one row of stationary blades (stators) and one row of moving blades (rotors). As shown in Fig. 1.1, wake/rotor interaction causes unsteadiness because the stator wakes, which one can assume to be approximately steady in the stator frame of reference, are unsteady in the rotor frame of reference since the rotor is moving through the wakes and chopping them into pieces. This causes unsteady forces on the rotor blades and generates unsteady pressure waves. Although the stator wakes are generated by viscosity, the subsequent interaction with the rotor blades is primarily an inviscid process and so can be modelled by the inviscid equations of motion. This allows two different approaches in numerical modelling. The first is to perform a full unsteady Navier-Stokes calculation of the stator and rotor blades. The second is to perform an unsteady inviscid calculation for just the rotor blade row, with the wakes being somehow specified as unsteady inflow boundary conditions. This latter approach is computationally much more efficient, but assumes that one is not concerned about the unsteady heat transfer and other viscous effects on the rotor blades. Potential stator/rotor interaction causes unsteadiness due to the fact that the pressure in the region between the stator and rotor blade rows can be decomposed approximately into a part that is steady and uniform, a part that is non-uniform but steady in the rotor frame (due to the lift on the rotor blades) and a part that is non-uniform but steady in the stator frame (due to the lift on the stator blades). As the rotor blades move, the stator trailing edges experience an unsteady pressure due to the non-uniform part that is locked to the rotors, and the rotor leading edges experience an unsteady pressure due to the non-uniform part that is locked to the stators. This is a purely inviscid interaction which is why it is labelled a "potential" interaction. There are again two approaches to modelling this interaction. The first is an unsteady, inviscid calculation of the stator and rotor blade rows. The second is an unsteady, inviscid calculation of just one of the blade rows, either the stator or the rotor, with the unsteady pressure being specified as a boundary condition. The latter approach is more efficient, but unfortunately the situation in which the potential stator/rotor interaction becomes important is when the spacing between the stator and rotor rows is extremely small, and/or there are shock waves moving in the region between them. Consequently, one does not usually know what values to specify as unsteady boundary conditions. The first two sources of unsteadiness were both due to the relative motion of the stator and rotor rows. The remaining two sources are not. The viscous flow past a blunt turbine trailing edge results in vortex shedding, very similar to the Karman vortex street shed behind a cylinder. In fact real wakes lie somewhere between the two idealized limits of a Karman vortex street and a turbulent wake with steady mean velocity profile. It is believed that provided the integrated loss is identical the choice of model does not affect the subsequent interaction with the downstream rotor blade row. However, this is an assumption which needs to be investigated sometime in the future. The importance of vortex shedding lies in the calculation of the average pressure around the blunt trailing edge, which determines the base pressure loss, a significant component of the overall loss. There is also experimental evidence to suggest that the vortex shedding can be greatly amplified under some conditions by the potential stator/rotor interaction. Finally, there can be unsteadiness due to the motion of the stator or rotor blades. The primary concern here is the avoidance of flutter. This is a condition in which a small oscillation of the blade produces an unsteady force and moment on the blade which due to its phase relationship to the motion does work on the blade and so increases the amplitude of the blade's unsteady motion. This can rapidly lead to very large amplitude blade vibrations, and ultimately blade failure.
Download or read book UNSFLO a Numerical Method for Unsteady Inviscid Flow in Turbomachinery written by Massachusetts Institute of Technology. Gas Turbine Laboratory and published by . This book was released on 1988 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solution adaptive Calculation of Unsteady Blade Row Interactions in Transonic Turbomachinery written by Scott M. Richardson and published by . This book was released on 1996 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the development of an implicit, viscous method for the solution of the quasi-three-dimensional flow equations for rotor-stator interaction in transonic turbomachinery. The flow algorithm is described, followed by the implicit time-marching scheme, and the one-equation turbulence model. The algorithm is implemented on an unstructured grid arrangement of locally structured micro-blocks called 'patches.' Solution-dependent adaptation is used to refine the grid in regions containing flow features which require enhanced resolution. An overlapped sliding grid interface is used to transfer flow equation information between the respective blade grids. The resulting computational algorithm has been used to perform a number of validation exercises and has been demonstrated on a modern transonic turbine stage. Where possible, these results are compared with experimental data and show the ability of the method to accurately capture the unsteady flow physics in a robust and computationally efficient manner.
Download or read book Unsteady Aerodynamics and Aeroelasticity of Turbomachines written by Torsten H. Fransson and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 835 pages. Available in PDF, EPUB and Kindle. Book excerpt: Twenty-one years have passed since the first symposium in this series was held in Paris (1976). Since then there have been meetings in Lausanne (1980), Cambridge (1984), Aachen (1987), Beijing (1989), Notre Dame (1991) and Fukuoka (1994). During this period a tremendous development in the field of unsteady aerodynamics and aeroelasticity in turbomachines has taken place. As steady-state flow conditions become better known, and as blades in the turbomachine are constantly pushed towards lower weight, and higher load and efficiency, the importance of unsteady phenomena appear more clearly. th The 8 Symposium was, as the previous ones, of high quality. Furthermore, it presented the audience with the latest developments in experimental, numerical and theoretical research. More papers than ever before were submitted to the conference. As the organising committee wanted to preserve the uniqueness of the symposium by having single sessions, and thus mingle speakers and audience with different backgrounds in this interdisciplinary field, only a limited number of papers could be accepted. 54 papers were accepted and presented at the meeting, all of which are included in the present proceedings.
Download or read book Three Dimensional Unsteady Turbomachinery Flow Analysis written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Loosely Couple Blade Row (LCBR) numerical method is developed to analyze the unsteady flow field of a three-dimensional multi-blade-row turbomachinery problem. This method allows the use of initial blade numbers for unsteady calculation and only one blade channel per blade row is used. Circumferential average approach to obtain a converged steady solution as the initial condition is adopted for unsteady calculation. Relatively, it not only maintains the blade configuration, but is also computationally more efficient. The numerical method used is a compressible viscous finite volume algorithm solving Reynolds averaged Navier-Stokes equations. Artificial dissipation terms similar to that used by Jameson is adopted to suppress the numerical oscillations. Four-Stage Runge-Kutta scheme is used to advance the flow equations in time. Residual smoothing and multi-grid techniques are employed to accelerate the convergence. Baldwin and Lomax algebraic turbulent model is used for the calculation of eddy viscosity. The UTRC (United Technologies Research Center) large scale turbine is used here as the test case. The unsteady flow predicted correlates well with data. The results indicate that the unsteady turbomachinery flowfield can be solved with single flow channel of unequal pitch on each blade row.
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 Unsteady Computational Fluid Dynamics in Aeronautics written by P.G. Tucker and published by Springer Science & Business Media. This book was released on 2013-08-30 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of Large Eddy Simulation (LES) and hybrids is a vibrant research area. This book runs through all the potential unsteady modelling fidelity ranges, from low-order to LES. The latter is probably the highest fidelity for practical aerospace systems modelling. Cutting edge new frontiers are defined. One example of a pressing environmental concern is noise. For the accurate prediction of this, unsteady modelling is needed. Hence computational aeroacoustics is explored. It is also emerging that there is a critical need for coupled simulations. Hence, this area is also considered and the tensions of utilizing such simulations with the already expensive LES. This work has relevance to the general field of CFD and LES and to a wide variety of non-aerospace aerodynamic systems (e.g. cars, submarines, ships, electronics, buildings). Topics treated include unsteady flow techniques; LES and hybrids; general numerical methods; computational aeroacoustics; computational aeroelasticity; coupled simulations and turbulence and its modelling (LES, RANS, transition, VLES, URANS). The volume concludes by pointing forward to future horizons and in particular the industrial use of LES. The writing style is accessible and useful to both academics and industrial practitioners. From the reviews: "Tucker's volume provides a very welcome, concise discussion of current capabilities for simulating and modellng unsteady aerodynamic flows. It covers the various pos sible numerical techniques in good, clear detail and presents a very wide range of practical applications; beautifully illustrated in many cases. This book thus provides a valuable text for practicing engineers, a rich source of background information for students and those new to this area of Research & Development, and an excellent state-of-the-art review for others. A great achievement." Mark Savill FHEA, FRAeS, C.Eng, Professor of Computational Aerodynamics Design & Head of Power & Propulsion Sciences, Department of Power & Propulsion, School of Engineering, Cranfield University, Bedfordshire, U.K. "This is a very useful book with a wide coverage of many aspects in unsteady aerodynamics method development and applications for internal and external flows." L. He, Rolls-Royce/RAEng Chair of Computational Aerothermal Engineering, Oxford University, U.K. "This comprehensive book ranges from classical concepts in both numerical methods and turbulence modelling approaches for the beginner to latest state-of-the-art for the advanced practitioner and constitutes an extremely valuable contribution to the specific Computational Fluid Dynamics literature in Aeronautics. Student and expert alike will benefit greatly by reading it from cover to cover." Sébastien Deck, Onera, Meudon, France
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 Paper written by and published by . This book was released on 2001 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Computational Fluid and Aerodynamics written by Paul G. Tucker and published by Cambridge University Press. This book was released on 2016-03-15 with total page 589 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book outlines the computational fluid dynamics evolution and gives an overview of the methods available to the engineer.
Download or read book IUTAM Symposium Transsonicum IV written by H. Sobieczky and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Symposium Transsonicum" was founded by Klaus Oswatitsch four decades ago when there was clearly a need for a systematic treatment of flow problems in the higher speed regime in aeronautics. The first conference in 1962 brought together scientists concerned with fundamental problems involving the sonic flow speed regime. Results of the conference provided an understanding of some basic tran sonic phenomena by proposing mathematical methods that allowed for the de velopment of practical calculations. The "Transonic Controversy" (about shock free flows) was still an open issue after this meeting. In 1975 the second symposium was held, by then there was much understanding in how to avoid shocks in a steady plane flow to be designed, but still very little was known in unsteady phenomena due to a lack of elucidating experiments. A third meeting in 1988 reflected the availability oflarger computers which allowed the numerical analysis of flows with shocks to a reasonable accuracy. Because we are trying to keep Oswatitsch's heritage in science alive especially in Gottingen, we were asked by the aerospace research community to organize another symposium. Much had been achieved already in the knowledge, techno logy and applications in transonics, so IUT AM had to be convinced that a fourth meeting would not just be a reunion of old friends reminiscing some scientific past. The scientific committee greatly supported my efforts to invite scientists ac tively working in transonic problems which still pose substantial difficulties to ae rospace and turbomachinery industry.
Download or read book Flow Simulation with High Performance Computers II written by Ernst Heinrich Hirschel and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: Der Band enthält den Abschlußbericht des DFG-Schwerpunktprogramms "Flußsimulation mit Höchstleistungsrechnern". Es führt die Arbeiten fort, die schon als Band 38 in der Reihe "Notes on Numerical Fluid Mechanics" erschienen sind.Work is reported, which was sponsored by the Deutsche Forschungsgemeinschaft from 1993 to 1995. Scientists from numerical mathematics, fluid mechanics, aerodynamics, and turbomachinery present their work on flow simulation with massively parallel systems, on the direct and large-eddy simulation of turbulence, and on mathematical foundations, general solution techniques and applications. Results are reported from benchmark computations of laminar flow around a cylinder, in which seventeen groups participated.
Download or read book Engineering Turbulence Modelling and Experiments 3 written by G. Bergeles and published by Newnes. This book was released on 2012-12-02 with total page 932 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents and discussses new developments in the area of turbulence modelling and measurements, with particular emphasis on engineering-related problems. At present, turbulence is one of the key issues in tackling engineering flow problems. Powerful computers and numerical methods are now available for solving the flow equations, but the simulation of turbulence effects which are nearly always important in practice, is still in an unsatisfactory state and introduces considerable uncertainities in the accuracy of CFD calculations. These and other aspects of turbulence modelling and measurements are dealt with in detail by experts in the field. The resulting book is an up-to-date review of the most recent research in this exciting area.
Download or read book High Performance Computing in Science and Engineering 98 written by Egon Krause and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book contains reports about the most significant projects from science and industry that are using the supercomputers of the Federal High Performance Computing Center Stuttgart (HLRS). These projects are from different scientific disciplines, with a focus on engineering, physics and chemistry. They were carefully selected in a peer-review process and are showcases for an innovative combination of state-of-the-art physical modeling, novel algorithms and the use of leading-edge parallel computer technology. As HLRS is in close cooperation with industrial companies, special emphasis has been put on the industrial relevance of results and methods.
Download or read book Journal of Turbomachinery written by and published by . This book was released on with total page 852 pages. Available in PDF, EPUB and Kindle. Book excerpt:
