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Self-excited oscillation properties of the profile NACA0015 in subsonic flow
Zolotarev, Igor ; Vlček, Václav ; Kozánek, Jan
Self-excited oscillations of the profile NACA0015 in subsonic flow were realized in the wind tunnel. The plunge support had the same elasticity for all experiments, the pitch support had seven different elasticity parameters. During our experiments different types of selfexcited vibration (flutter, stall flutter) were observed. Range of Mach numbers was M = 0.08–0.45, corresponding range of Reynolds numbers is Re = (1–5)·105, when the chord length is used as the characteristic dimension of the profile.\n
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Some experimentally determined properties of a profile in case of self-excited oscillations in subsonic flow
Vlček, Václav ; Zolotarev, Igor ; Kozánek, Jan ; Šidlof, Petr ; Štěpán, M.
In the wind tunnel of the Institute of Thermomechanics of the AS CR,v .v. i., experiments were realized with the profile NACA0015 in the presence of the self-excited oscillation. The oscillation of the profile with pitch and plunge degrees of freedom was excited by the subsonic air flow. The plunge support had the same elasticity for all experiments, the pitch support had seven different values of elasticity. Within experiments different types of self-excited vibration (flutter, stall flutter, deep stall flutter) were realized. Range of Mach numbers were M=0.08–0.45, when the chord length is used as the characteristic dimension of the profile. The frequency and amplitude characteristics of the oscillating profile were experimentally determined.\n
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Evaluation of Interferograms of Unsteady Subsonic Airflow Past a Fluttering Airfoil
Šidlof, P. ; Riss, Š. ; Vlček, Václav
The paper reports on time-resolved interferometric measurements of unsteady ow elds around a uttering NACA0015 airfoil. A mechanical model with two degrees of freedom (pitch and plunge) has been designed and tested in a high-speed subsonic wind tunnel. Aeroelastic instability of the classical utter and dynamic stall type has been observed in the Mach number range M = 0.2 - 0.5. The interferograms were recorded using a Mach-Zehnder interferometer and a high-speed camera. An in-house software IFGPro was developed for the postprocessing and evaluation of the interferogram sequences, yielding pressure distribution, lift and drag force on the airfoil.
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