Author : National Aeronautics and Space Administration (NASA)
Release : 2018-08-16
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Kind : eBook
Book Rating : 888/5 ( reviews)

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Book Synopsis Calculation of Unsteady Linearized Euler Flows in Cascades Using Harmonically Deforming Grids by : National Aeronautics and Space Administration (NASA)

Download or read book Calculation of Unsteady Linearized Euler Flows in Cascades Using Harmonically Deforming Grids written by National Aeronautics and Space Administration (NASA). This book was released on 2018-08-16. Available in PDF, EPUB and Kindle. Book excerpt: A method for calculating unsteady, inviscid, compressible flows in cascades is presented. Using the linearized Euler technique, the flow is decomposed into a steady or mean flow plus a harmonically varying small disturbance flow. The equations that describe the small disturbance flow are linear variable coefficient equations, and are solved using a pseudo-time time marching Lax-Wendroff technique. Unlike previous linearized methods, however, the solution is computed on a harmonically deforming computational grid that conforms to the motion of the vibrating airfoils. The mean flow and perturbation flow solutions are defined in the deforming coordinate system rather than in a coordinate system fixed in space. Hence, no extrapolation terms are required to implement the upwash boundary conditions at the airfoil surfaces, significantly improving the accuracy of the method. For transonic flow calculations, unsteady shock motions are modelled using shock capturing. The unsteady loads due to the shock motion are then seen as pressure impulses. Representative computational results are presented for transonic channel flows and subsonic and transonic cascade flows. Hall, Kenneth C. and Clark, William S. Unspecified Center NASA-CR-188916, NAS 1.26:188916 NAG3-1192...