Download or read book Benchmark Solutions for Computational Aeroacoustics Caa Code Validation written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-21 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: NASA has conducted a series of Computational Aeroacoustics (CAA) Workshops on Benchmark Problems to develop a set of realistic CAA problems that can be used for code validation. In the Third (1999) and Fourth (2003) Workshops, the single airfoil gust response problem, with real geometry effects, was included as one of the benchmark problems. Respondents were asked to calculate the airfoil RMS pressure and far-field acoustic intensity for different airfoil geometries and a wide range of gust frequencies. This paper presents the validated that have been obtained to the benchmark problem, and in addition, compares them with classical flat plate results. It is seen that airfoil geometry has a strong effect on the airfoil unsteady pressure, and a significant effect on the far-field acoustic intensity. Those parts of the benchmark problem that have not yet been adequately solved are identified and presented as a challenge to the CAA research community. Scott, James R. Glenn Research Center NASA/TM-2004-213386, IMECE2004-59865, E-14894

Download or read book Validation of a CAA Code for a Case of Vortical Gust stator Interaction written by Christopher P. Durand and published by . This book was released on 2016 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, the solution of the NASA Glenn Research Center Broadband Aeroacoustic Stator Simulation (BASS) Computational Aeroacoustics (CAA) code to a benchmark problem has been presented. The test case used for this work is the Category 3 problem from the NASA Second CAA Workshop on Benchmark Problems, which is a 2D gust--cascade problem involving the interaction of an incident vortical gust with a row of infinitely thin stator blades. It has been found that BASS accurately predicts the magnitude of the cut-on acoustic modes that result from the gust impinging on the blades for both the low frequency and the high frequency benchmark case. Spurious reflections from the upstream and downstream boundaries are present in the solution due to limitations of the boundary conditions. Absorbing layers were used to minimize reflections from the boundary, with favorable results achieved by both using absorbing layers and increasing the axial length of the computational domain. Results also have been presented that suggest that dispersion relation-preserving (DRP) spatial differencing schemes may not accurately resolve the decay rate of decaying acoustic waves with an economical number of grid points per wavelength. This work does not suggest a solution to this issue, but provides a general overview of the problem in order to help form a basis for future research.

Download or read book Second Computational Aeroacoustics CAA Workshop on Benchmark Problems written by C. K. W. Tam and published by . This book was released on 1997 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proceedings of the ASME Noise Control and Acoustics Division written by and published by . This book was released on 2004 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Asymptotic Approximations for the Sound Generated by Aerofoils in Unsteady Subsonic Flows written by Lorna Ayton and published by Springer. This book was released on 2015-06-15 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigates the sound generated by solid bodies in steady subsonic flows with unsteady perturbations, as is typically used when determining the noise generated by turbulent interactions. The focus is predominantly on modelling the sound generated by blades within an aircraft engine, and the solutions are presented as asymptotic approximations. Key analytical techniques, such as the Wiener-Hopf method, and the matched asymptotic expansion method are clearly detailed. The results allow for the effect of variations in the steady flow or blade shape on the noise generated to be analysed much faster than when solving the problem numerically or considering it experimentally.

Download or read book ICASE LaRC Workshop on Benchmark Problems in Computational Aeroacoustics CAA written by Jay C. Hardin and published by . This book was released on 1995 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multifield Problems in Solid and Fluid Mechanics written by Rainer Helmig and published by Springer Science & Business Media. This book was released on 2006-11-28 with total page 569 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives an overview of the research projects within the SFB 404 "Mehrfeldprobleme in der Kontinuumsmechanik". The book is for researchers and graduate students in applied mechanics and civil engineering.

Download or read book Verification of a Computational Aeroacoustics Code Using External Verification Analysis EVA written by Daniel Ingraham and published by . This book was released on 2010 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: As Computational Aeroacoustics (CAA) codes become more complex andwidely used, robust Verification of such codes becomes more and more important. Recently, Hixon et al. proposed a variation of the Method of Manufactured Solutions of Roache especially suited for Verifying unsteady CFD and CAA codes that does not require the generation of source terms or any modification of the code being Verified. This work will present the development of the External Verification Analysis (EVA) method and the results of its application to some popular model equations of CFD/CAA and a high-order nonlinear CAA code.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2007 with total page 1184 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A High order High accuracy Geometric Block Interface Treatment for Computational Aeroacoustics Codes written by Nima Mansouri and published by . This book was released on 2016 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical performance in computational aeroacoustics (CAA) has driven the use of structured multi-block codes for modeling problems in the aeronautic industry. Structured grids reduce the amount of communication in a numerical simulation, leading to higher computational speeds and lower cost. CAA codes are applied to real problems, so they must be capable of handling complex geometries. The structure of the complex geometries may lead to grid discontinuities and/or singularities at block interfaces. These discontinuities are the primary sources of error in the codes, significantly reducing a codes performance. The geometric block interface treatment (GBIT) is a new approach to improve grid block discontinuity issues at block interfaces for structured multi-block codes. This article first reviews what researchers have done to treat block interfaces. Then, the mathematical model of our geometry-based treatment is proposed. This method was implemented in the high-order, high-accuracy NASA Glenn Research Center Broadband Aeroacoustic Stator Simulation (BASS) CAA code. Here, the initial results for two-dimensional test cases are shown. To determine the performance of the new method, the results are verified by Ingraham's External Verification Approach (EVA). Initial results are promising and reach expected convergence rate. However, instability and inaccuracy appear in the solution. Artificial dissipation and special differencing schemes are revealed to be the main causes of instability and inaccuracy, respectively. To overcome these problems, interior dissipation stencils replace biased stencils at interface regions. Smooth grid clustering is proposed to improve the accuracy of the spatial schemes performance near interfaces, which consequently strengthens the accuracy of the solution. All these new results are laid out, verified, and implemented in basic form.

Download or read book Evaluation of Far Field Boundary Conditions for the Gust Response Problem written by and published by . This book was released on 2002 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Institute for Computational Mechanics in Propulsion ICOMP written by and published by . This book was released on 1995 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Journal of the Acoustical Society of America written by Acoustical Society of America and published by . This book was released on 2004 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1995 with total page 938 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 36th Aerospace Sciences Meeting Exhibit written by and published by . This book was released on 1998 with total page 614 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Institute for Computational Mechanics in Propulsion ICOMP written by Charles E. Feiler and published by . This book was released on 1994 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: