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Preliminary Compressor Design Method Development. Development of an S1-S2 calculation system for axial flow compressors.

Daniel Lindblad
Göteborg : Chalmers tekniska högskola, 2014. Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, ISSN 1652-8557; 2014:38, 2014.
[Examensarbete på avancerad nivå]

The design of modern, transonic, axial flow compressors for applications within aero engines is a very complex process that is divided into many stages. It starts with fairly primitive methods to lay out the overall design, and ends with sophisticated 3D simulations using Computational Fluid Dynamics (CFD). In between these stages, through flow methods are applied to design the annular geometry and spanwise variations of blade shapes. These methods are dependent on correlations, which often have problems in predicting the performance of modern blade designs. This makes the step between the through flow method and the CFD method large, since the design predicted by the through flow method often turn out insufficient when reality is approached in 3D CFD. In this work, a possible remedy to this problem is investigated by coupling the streamline curvature (SLC) through flow code SC90C with a Quasi-Three-Dimensional (Q3D) blade-to-blade method. The blade-to-blade method is used to correct the correlations used in SC90C in order to get better predictions for the performance of arbitrary blade designs. The coupling is done in the Python 3 programming language to obtain a fully automated S1-S2 calculation system. In the SLC method, the inviscid momentum equations, together with the continuity and energy equations, are rewritten in a form suitable for the geometry of the compressor annulus. These are solved in conjunction with correlations on a mesh laid out between the hub and shroud, using a finite difference scheme. The blade-to-blade flow is modeled using the Favre averaged Navier-Stokes equations and the standard "k-epsilon" turbulence model. These are solved using a finite volume discretization method on a mesh having the shape of a streamtube passing over the blade. A special source term is also used to model the pressure gradient normal to the flow. This removes the necessity of resolving it, resulting in a smaller mesh size and less time consuming simulations. The S1-S2 system is used to predict the performance of a three-stage transonic compressor and the results are compared to 3D CFD. The results are promising, but also identifies several restrictions in the approach currently employed. These will have to be investigated further if the method should be applied in the future.

Nyckelord: Axial Flow Compressor, Compressible Flow, Compressor Performance, Computational Fluid Dynamics, CFD, Finite Volume Method, FVM, Quasi-Three-Dimensional Blade-To-Blade Calculations, Q3D, S1-S2 Calculation System, Streamline Curvature Method, SLC, Streamtube Source Term, Turbulence Modeling, Unsteady Favre averaged Navier-Stokes Equations



Publikationen registrerades 2015-07-07. Den ändrades senast 2015-12-10

CPL ID: 219542

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