NAFEMS International Journal of CFD Case Studies

Volume 11, April 2016

ISSN 1462-236X

Validation of Experimental Results of a Realistic Natural Laminar Swept Wing through Advanced Stability Methods

D de Rosa¹, R S Donelli¹ and D G Romano^2
1CIRA, Italy
²Piaggio Aero Industries S.p.A., Italy

https://doi.org/10.59972/0ztkg0mu

Keywords: Laminar Wings, Advanced Stability and Euler Code,

Abstract

Stability theory, coupled with the eⁿ method, offers a rational approach to transition prediction in a variety of flow conditions. Stability analyses are sensitive to the quality of the mean flow and require an adequate resolution in the boundary layer region. Navier-Stokes analyses for stability investigations are often not affordable because of the large number of points normal to the wall, necessary in the viscous layer, that makes computations extremely time consuming. Moreover, the definition of the boundary layer edge is not a straightforward task. For these reasons, according to the approach here investigated, the mean flow is evaluated using an Euler code, where the viscous flow is obtained through a boundary-layer code. In particular, the work performed is made-up of two different steps.
First of all, it is necessary to perform Euler computations to evaluate the basic non-viscous flow. Subsequently, the application of boundary-layer code allows the boundary layer to be computed and to perform the linear stability analysis.
In the past years several projects, both experimental and numerical, aimed to design laminar wings and to study their performances were carried out. Most of the projects are restricted, so it turns out to be difficult to retrieve experimental data. In the present work, the reference geometry is a laminar wing developed by CIRA (Centro Italiano Ricerche Aerospaziali) and PAI (Piaggio Aero Industries) in the framework of an Italian national program called VITAS (Vettore Innovativo per il Trasporto AeroSostenibile) [1]. Four different test cases have been selected among the available experimental results. The chosen conditions were the ones for which both the best IR (Infra-Red) camera results and the pressure distributions results were available.
Euler computations have been performed using the commercial CFD (Computational Fluid Dynamic) code CFD++ [2] and the boundary layer computations have been performed using the ONERA (Office National d'Études et de Recherches Aérospatiales) 3C3D laminar/turbulent boundary layer code [3,4], while the stability computations will be performed in the next step of the work related to the project using the 3D compressible code NOLLI (NOn Local Linear Instability code) developed in house by CIRA and based on the application of the multiple scale technique and ray tracing theory [5, 6, 7]. Fixed span-wise wavenumber β strategy will be used.

References

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[8] DE ROSA, D. and DONELLI, R. S. (2012) Geometry selected for receptivity and ray tracing investigations. RECEPT Deliverable D4.1, CIRA.

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Cite this paper

D de Rosa, R S Donelli, D G Romano, Validation of Experimental Results of a Realistic Natural Laminar Swept Wing through Advanced Stability Methods, NAFEMS International Journal of CFD Case Studies, Volume 11, 2016, Pages 91-111, https://doi.org/10.59972/0ztkg0mu