On the Theory of Force Elements with Turbulence Effects：Large-Eddy Simulation
Date Issued
2015
Date
2015
Author(s)
Liu, Kung-Wei
Abstract
In this study, turbulence effects on a NACA-0012 airfoil at Reynolds number of 20,700 and the angles of attack (AOA) = 5^° and 〖10〗^° are investigated through the force element theory. Flow fields are computationally obtained through the large-eddy simulation (LES). The computation is carried out on the body-fitted grids with the H-type orthogonal-grid construction. The study extends the force element theory (Chang (1992)) to the analysis for the turbulent flow filed. Turbulence effects can be divided into the computationally resolved field and the sub-grid-scale (SGS) model on the framework of LES. The total force contribution and the local effect of turbulence to the infinite wing are examined, and the results show that both give insignificant effect. Moreover, in the case of AOA = 〖10〗^°, the temporary extreme value of turbulent kinetic energy is investigated. It is found that the extreme is resulting from the interaction between turbulent fluctuation and the trailing-edge wakes. We also measure the resulting increase of turbulent fluctuation, which in turn causes the high ratio of lift and drag contribution due to the local fluctuation.
Subjects
force element theory
turbulence
large-eddy simulation
low-Reynolds-number
Type
thesis
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