Download or read book Computations of Unsteady Multistage Compressor Flows in a Workstation Environment written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-16 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-end graphics workstations are becoming a necessary tool in the computational fluid dynamics environment. In addition to their graphic capabilities, workstations of the latest generation have powerful floating-point-operation capabilities. As workstations become common, they could provide valuable computing time for such applications as turbomachinery flow calculations. This report discusses the issues involved in implementing an unsteady, viscous multistage-turbomachinery code (STAGE-2) on workstations. It then describes work in which the workstation version of STAGE-2 was used to study the effects of axial-gap spacing on the time-averaged and unsteady flow within a 2 1/2-stage compressor. The results included time-averaged surface pressures, time-averaged pressure contours, standard deviation of pressure contours, pressure amplitudes, and force polar plots. Gundy-Burlet, Karen L. Ames Research Center NASA-TM-103839, A-91074, NAS 1.15:103839 RTOP 505-60-00...

Download or read book Computations of Unsteady Multistage Compressor Flows in a Workstation Environment written by and published by . This book was released on 1992 with total page 18 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 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Computational Fluid Dynamics written by Vijay K. Garg and published by CRC Press. This book was released on 1998-05-08 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Describes the latest techniques and real-life applications of computational fluid dynamics (CFD) and heat transfer in aeronautics, materials processing and manufacturing, electronic cooling, and environmental control. Includes new material from experienced researchers in the field. Complete with detailed equations for fluid flow and heat transfer."

Download or read book ASME Technical Papers written by and published by . This book was released on 2001 with total page 488 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 Modeling Multi stage Flows and Aeroelasticity in Transonic Gas Turbine Compressors written by Roy Milton Culver and published by . This book was released on 2009 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern desire to have turbomachines perform over a large range of conditions raises concerns as to their susceptibility to potentially harmful vibrations induced by the unsteady flows encountered at conditions far from the design point. Machines demonstrating this type of behavior may be damaged by fatigue or be subject to catastrophic failure. Due to these concerns and the relative expense and difficulty in obtaining accurate experimental data for fluid-structure interaction in turbomachines, computations have been and will continue to be an indispensable part of the design and research efforts focused on avoiding such phenomena. While the traditional computational analysis considering a single isolated blade row can aid in understanding the mechanisms that initiate vibrations in turbomachines, study of multiple blade rows may be necessary to completely model the underlying causes of these vibrations. In the present work, the mixing-plane and sliding-mesh methods are used to simulate both steady and unsteady multi-stage transonic compressor flows. The simulations conducted here include the solution of the compressible unsteady Reynolds Averaged Navier Stokes (RANS) Equations. The Spalart Almaras model is used to simulate the effects of turbulence in the flow field. A modal superposition method is used to model fluid-structure interaction resulting from blade vibration. Steady flow through the NASA Stage 35 transonic compressor is computed using the mixing-plane method, and reasonable agreement is obtained with experimental data and previous computations. Steady and unsteady computations are also performed for a modern 1.5-stage transonic compressor design provided by Siemens. For this case, experiments indicate the appearance of low frequency, large amplitude flow oscillations which could potentially lead to unwanted structural vibration. In performing unsteady computations for the Siemens compressor, effects of the periodic domain size for the sliding-mesh computations are considered by doubling and tripling the initial domain size. Computations performed on the triple-sized domain show a qualitatively different character than those performed with the two smaller domains. While this result cannot guarantee that the large domain has fully resolved the unsteady flow, it provides a strong argument that the two smaller domains have not, and highlights the need to clearly identify the circumferential wavelengths expected in an unsteady multi-stage flow. Fluid-structure interaction computations for this case show very small amplitude vibrations.

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Download or read book Monthly Catalog of United States Government Publications written by and published by . This book was released on 1993 with total page 962 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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Download or read book NAS Technical Summaries Numerical Aerodynamic Simulation Program March 1990 February 1991 written by and published by . This book was released on 1991 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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Download or read book Research and Technology Program Digest written by United States. National Aeronautics and Space Administration and published by . This book was released on with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book AGARD Lecture Series written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development and published by . This book was released on 199? with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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Download or read book Experimental Analysis of the Unsteady Flow and Instabilities in a High speed Multistage Compressor written by Nicolas Courtiade and published by . This book was released on 2012 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work is a result of collaboration between the LMFA (Laboratoire de Mécanique des Fluides et d'Acoustique, Ecole Centrale de Lyon - France), Snecma and the Cerfacs. It aims at studying the flow in the 3.5-stages high-speed axial compressor CREATE (Compresseur de Recherche pour l'Etude des effets Aérodynamique et TEchnologique - rotation speed: 11543 RPM, Rotor 1 tip speed: 313 m/s), designed and built by Snecma and investigated at LMFA on a 2-MW test rig. Steady measurements, as well as laser velocimetry, fast-response wall static and total pressure measurements have been used to experimentally investigate the flow. The analysis focuses on two main aspects: the study of the flow at stable operating points, with a special interest on the rotor-stator interactions, and the study of the instabilities arising in the machine at low mass flow rates.The description of the unsteady flow field at stable operating points is done through measurements of wall-static pressure, total pressure and velocity, but also total temperature, entropy and angle of the fluid. It is shown that the complexity and unsteadiness of the flow in a multistage compressor strongly increases in the rear part of the machine, because of the interactions between steady and rotating rows. Therefore, a modal analysis method developed at LMFA and based on the decomposition of Tyler and Sofrin is presented to analyze these interactions. It is first applied to the pressure measurements, in order to extract the contributions of each row. It shows that all the complex pressure interactions in CREATE can be reduced to three main types of interactions. The decomposition method is then applied to the entropy field extracted from URANS CFD calculations performed by the Cerfacs, in order to evaluate the impact of the interactions on the performance of the machine in term of production of losses.The last part of this work is devoted to the analysis of the instabilities arising in CREATE at low mass flows. It shows that rotating pressure waves appear at stable operating points, and increase in amplitude when going towards the surge line, until reaching a critical size provoking the onset a full span stall cell bringing the machine to surge within a few rotor revolutions. The study of these pressure waves, and the understanding of their true nature is achieved through the experimental results and the use of some analytical models. A precise description of the surge transient through wall-static pressure measurements above the rotors is also provided, as well as a description of a complete surge cycle. An anti-surge control system based on the detection of the amplitude of the pressure waves is finally proposed.