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COBEM 2021
26th International Congress of Mechanical Engineering
AIRFOIL TRANSITION TO TURBULENCE PREDICTION USING A SIMPLIFIED ENVELOPE METHOD
Submission Author:
Gustavo Padovany da Silva , PR
Co-Authors:
Gustavo Padovany da Silva, Waldyr De Lima e Silva Junior, Gustavo Luiz Olichevis Halila
Presenter: Gustavo Padovany da Silva
doi://10.26678/ABCM.COBEM2021.COB2021-0332
Abstract
The inclusion of transition to turbulence effects in numerical simulations has a direct influence on the ability of computational tools to correctly reproduce aerodynamic coefficients. While high-fidelity tools accounting for transition to turbulence are today largely used in airplane design during both the conceptual and preliminary phases, they still represent high computational costs. In order to better explore the design space in a reasonable time frame, designers also employ lower fidelity approaches in the early design phase. We investigate the transition to turbulence capabilities as implemented in Xfoil, which is a panel method code that includes viscous effects through boundary layer estimations. Within Xfoil, the transition to turbulence effects are included by means of the so-called approximate envelope method, which we also describe in this paper. We compare the results obtained with this lower fidelity tool with the ones obtained by using the high-fidelity, nonparallel and nonlocal Parabolized Stability Equations (PSE) technique. Our results indicate that Xfoil predicts the expected transition front upstream movement trend when the freestream Reynolds number and turbulence intensity are increased, even tough some offset is observed when comparing these numerical results with the ones obtained with higher-fidelity prediction tools. According to our numerical results, Xfoil is able to predict lift and drag coefficients for airfoils in transitional flow within levels of accuracy compatible with early-stage design requirements.
Keywords
transition to turbulence, Tollmien-Schlichting waves, Approximate Envelope Method, XFOIL
