Experiments and analysis for a gust generator in a wind tunnel

Tang, Deman; Cizmas, Paul G. A.; Dowell, Earl H.

doi:10.2514/3.46914

Cited by 70 publications

(35 citation statements)

References 5 publications

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“…(9) In this study we have used freeplay, δ = 2.12°, so that the nominal angular gap shown in Fig. (9) In this study we have used freeplay, δ = 2.12°, so that the nominal angular gap shown in Fig.…”

Section: Control Surface Nonlinearitymentioning

confidence: 99%

The Influence of a Nonzero Angle of Attack and Gust Loads on the Nonlinear Response of a Typical Airfoil Section with a Control Surface Freeplay

Kholodar¹,

Dowell²

2000

International Journal of Nonlinear Sciences and Numerical Simulation

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The influence of a "frozen" harmonic gust excitation on an aeroelastic nonlinear system with a control surface freeplay at nonzero angles of attack is examined in the context of a three-degree-of-freedom airfoil. The formulation of the numerical model is based on Theodorsen's aerodynamics and is extended to account for nonlinear arbitrary motion and gust loads. By time marching of the governing equations, the system response is determined and the complex nonlinear behavior is observed. Results indicate that there is no suppressing effect due to a nonzero mean angle of attack for such a system under gust loads. A companion experimental test program in a wind tunnel with a gust generator is used to validate the numerical results. The good agreement between theory and experiment demonstrates the efficiency and accuracy of the computational method.

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Section: Control Surface Nonlinearitymentioning

confidence: 99%

The Influence of a Nonzero Angle of Attack and Gust Loads on the Nonlinear Response of a Typical Airfoil Section with a Control Surface Freeplay

Kholodar¹,

Dowell²

2000

International Journal of Nonlinear Sciences and Numerical Simulation

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“…There are investigations with gust excitation in a wind tunnel in the low subsonic flight regime, for instance tests with the European Research Aeroelastic Model [6,7], and experiments at Duke University based on rotating slotted cylinders [8]. A gust generator using oscillating vanes mounted upstream of the wind tunnel test section was also developed in the NASA Langley Transonic Dynamics Tunnel [9].…”

Section: Introductionmentioning

confidence: 99%

Analysis of forced response in a wind tunnel based on Doublet-Lattice method

2011

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A wind tunnel experiment for the validation of gust response computations has been performed. The model consists of an active two-dimensional rigid front wing acting as a gust generator and forcing an elastic backswept rear wing. Results of numerical simulations with gust generation are presented. For the setup of the experiment, a simulation environment was established to identify the effect of different installation positions by parameter variation and to point out the efficiency of gust generation in the wind tunnel. The aerodynamic forces are computed by a subsonic Doublet-Lattice method (DLM) which provides considerable computational efficiency and flexibility of the numerical approach. DLM is used as a standard unsteady aerodynamic tool for gust problems and enables comparisons with CFD results. A large number of numerical results in frequency and time domain are used to obtain the forced motion of the elastic back-swept wing located downstream of the gust generator and to simulate the aerodynamic interaction in the wind tunnel. This enables a survey of gust loads on the back-swept wing in comparison to gust and turbulence loads calculated according to airworthiness standards. Furthermore, the numerical results are compared to the experimental results measured in the Transonic Wind tunnel Göttingen of the German-Dutch Wind Tunnels.

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“…The two foils are some distance apart and the useful flow perturbations are generated downstream of the foils in the horizontal plane of symmetry of the foil set-up. This approach was pioneered by Ham et al (1974) and has later also been used by Jancauskas & Melbourne (1980), Tang et al (1996), Passmore et al (2001), Delpero (1992) and Horwich (1993). In these pieces of work, only either longitudinal or vertical perturbations were generated.…”

Section: Introductionmentioning

confidence: 99%

Generating controllable velocity fluctuations using twin oscillating hydrofoils: experimental validation

2014

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A method for generating controllable two-dimensional velocity fluctuations using two pitching foils was derived theoretically in a previous companion paper. The present work describes the experimental implementation of the method. The experiments are carried out in a re-circulating water channel optimised to provide low turbulence intensity in the incoming flow. Velocities are measured using an acoustic Doppler velocimeter. The pitching motions of the foils are position-controlled using a closed-loop control system. Two velocity fluctuation patterns are investigated. They consist of a combination of sinusoidal components. Theoretical predictions and experimental measurements are compared in the time and frequency domain. Although some discrepancies are observed, the agreement is generally good and therefore validates the theoretical method for the conditions investigated.

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Experiments and analysis for a gust generator in a wind tunnel

Cited by 70 publications

References 5 publications

The Influence of a Nonzero Angle of Attack and Gust Loads on the Nonlinear Response of a Typical Airfoil Section with a Control Surface Freeplay

The Influence of a Nonzero Angle of Attack and Gust Loads on the Nonlinear Response of a Typical Airfoil Section with a Control Surface Freeplay

Analysis of forced response in a wind tunnel based on Doublet-Lattice method

Generating controllable velocity fluctuations using twin oscillating hydrofoils: experimental validation

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