On the Simulation of Complex Gusts at Low Reynolds Numbers

Wong, Jaime G.; Mohebbian, Ali; Kriegseis, Jochen; Rival, David E.

doi:10.2514/6.2012-2663

Cited by 5 publications

(5 citation statements)

References 7 publications

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“…The discrepancies can be justified b ased on the difference in t he Reynolds numbers. As discussed in Wong et al [2012] , the main difference between t he experimental and numerical data was found in the shear layer and wake where instabilities in the exp eriment (Re = 10000) were observed. In t he simulations, however, t he Reynolds number is sufficiently low (Re = 1600) to dampen out any instabilit ies.…”

Section: Validation Of Cfd Resultsmentioning

confidence: 95%

“…Chapter 3 discusses the numerical setup , which is used to produce a synthetic PIV velocity field. In addition, the numerical results presented in this study are validated with the experiments conducted by Wong et al [2012]. Chapter 4 provides the reader with the results obtained from the assessment of the DMT method.…”

Section: Measurementsmentioning

confidence: 84%

“…The results are compared bot h qualitatively and quantitatively to ensure that the PIV-like velocity field is acceptable in order to asses t he DMT method. Wong et al [2012] conducted a water tunnel experiments for a flat plate, which was moved sinusoidally under similar conditions compared to this study's simulation . Both the xperim nts and t he simulations a sume th ame gust and r duced frequen y (k = 0.25).…”

Section: Validation Of Cfd Resultsmentioning

confidence: 99%

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Assessment of the derivative-moment transformation method for unsteady-load estimation

Mohebbian

Rival

2012

Exp Fluids

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It is often difficult, if not impossible, to measure the aerodynamic or hydrodynamic forces on a moving body. For this reason, a traditional control-volume technique is typically ap plied to extract the unsteady forces. However, measuring the acceleration term within the volume of interest can be limited by optical access, reflections as well as shadows. There fore in this study an alternative approach, termed the Derivative-Moment Transformation (DMT) method, is introduced and tested on a synthetic data set produced using numerical simulations. The test case involves the unsteady loading of a flat plate in a two-dimensional, laminar periodic gust. The results suggest that the DMT method can accurately predict the acceleration term so long as appropriate spatial and temporal resolutions are maintained. It was shown that for large control volumes, and with realistic spatial resolution, the accuracy of the DMT method would also suffer. Therefore, a delicate compromise is required when selecting control-volume size in future experiments. lll l V

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Section: Validation Of Cfd Resultsmentioning

confidence: 95%

Section: Measurementsmentioning

confidence: 84%

Section: Validation Of Cfd Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Assessment of the derivative-moment transformation method for unsteady-load estimation

Mohebbian

Rival

2012

Exp Fluids

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“…For the sake of boundary effect elimination, all the computational domain boundaries were placed about 20 c from the airfoil surface. To capture the correct transitional boundary layer, the nondimensional wall distance is kept less than one, y + < 1.…”

Section: Methodsmentioning

confidence: 99%

“…It should be noted that recent studies have indicated that oscillation of the body instead of the oscillation of the freestream are not equivalent even at low frequencies. For the steady incident velocity, a uniform freestream ( U = U ∞ ) is considered, and for the unsteady freestream velocity, U ∞ = U mean . Both SOS and COS have the same frequency of oscillation, f , with the same reduced frequency ( k ), where

k MathClass-rel= \frac{π italicf c}{U_{MathClass-rel\infty}} MathClass-punc.

…”

Section: Simulated Casesmentioning

confidence: 99%

Effects of nonuniform incident velocity on a dynamic wind turbine airfoil

Gharali

Johnson

2014

Wind Energy

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For further insight into the performance of a horizontal axis wind turbine blade section under yaw loads, a 2D numerical simulation of a pitching S 809 airfoil under dynamic stall with an unsteady incident velocity is presented. The streamwise incident velocity and pitch angle of incidence oscillated with the same frequency but with a range of phase differences, ÄˆÄ . Changingˆcaused variation of the results, which can be highlighted as significantly augmented and dramatically damped dynamic stall loads, both increasing and decreasing trends for vortex growth time duringˆincrease, a shifted location of the maximum loads and a change in the order of the vortex pair circulation in each cycle. The results showed strong dependency on the velocity and acceleration of the freestream during dynamic stall, which categorized the results in four individual subdomains with different behaviors.

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