Airfoil drag at low-to-medium reynolds numbers: A novel estimation method

  • This paper presents a novel method for airfoil drag estimation at Reynolds numbers between 4×10⁵ and 4×10⁶. The novel method is based on a systematic study of 40 airfoils applying over 600 numerical simulations and considering natural transition. The influence of the airfoil thickness-to-chord ratio, camber, and freestream Reynolds number on both friction and pressure drag is analyzed in detail. Natural transition significantly affects drag characteristics and leads to distinct drag minima for different Reynolds numbers and thickness-to-chord ratios. The results of the systematic study are used to develop empirical correlations that can accurately predict an airfoil drag at low-lift conditions. The new approach estimates a transition location based on airfoil thickness-to-chord ratio, camber, and Reynolds number. It uses the transition location in a mixed laminar–turbulent skin-friction calculation, and corrects the skin-friction coefficient for separation effects. Pressure drag is estimated separately based on correlations of thickness-to-chord ratio, camber, and Reynolds number. The novel method shows excellent accuracy when compared with wind-tunnel measurements of multiple airfoils. It is easily integrable into existing aircraft design environments and is highly beneficial in the conceptual design stage.

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Metadaten
Author:Falk GöttenORCiD, Marc Havermann, Carsten BraunORCiD, Matthew Marino, Cees Bil
DOI:https://doi.org/10.2514/1.J058983
ISSN:1533-385X
Parent Title (English):AIAA Journal
Publisher:AIAA
Place of publication:Reston, Va.
Document Type:Article
Language:English
Year of Completion:2020
Date of the Publication (Server):2020/08/14
Volume:58
Issue:7
First Page:2791
Last Page:2805
Link:https://doi.org/10.2514/1.J058983
Zugriffsart:bezahl
Institutes:FH Aachen / Fachbereich Luft- und Raumfahrttechnik
collections:Verlag / American Institute of Aeronautics and Astronautics (AIAA)