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Aeroelastic experiments with the structural properties variation
Chládek, Štěpán ; Zolotarev, Igor ; Uruba, Václav
The paper measurements on a model of the airfoil NACA0012. Usually there is a limit range of the flow velocity in the wind tunnel. The chosen wind tunnel is usually fixed, the only one possibility is to modify the structural properties of the experimental stand. There are presented two kinds of modifications, one is based on the geometry variation, the other one on the added mass approach. Both of them have been verified experimentally.
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Dynamics of flow around vibrating wing NACA 0012
Uruba, Václav
Flow around vibrating wing consisting of airfoil profile NACA 0012 has been studied experimentally using time resolved PIV technique. The unsteady velocity field close to the profile trailing edge is highly affected by the wing vibrations. The dynamic of the flow is analyzed using BOD technique of the flow-field for cases with and without vibrations. Comparison shows strong influence of the airfoil vibrations on the flow dynamics.
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Interaction and Feedbacks 2012
Zolotarev, Igor
Proceedings INTERACTION AND FEEDBACKS 2012 deals with the problems of interactions of dynamic systems with surrounding liquid or fluent environment and the solutions of the dynamic systems with feedbacks.
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The calculation of the forces and moments acting on the fluttering profile using interferometric measurements
Vlček, Václav ; Kozánek, Jan ; Zolotarev, Igor
Experimental investigation of the profile NACA0015 fixed as a dynamic system with two degree of freedom vibrating in self-excitation modes were measured in the wind tunnel of the Institute of Thermomechanics AS CR by interoferometric methods. The profile moved in the vertical direction and rotated around the elastic axis in 1/3 of the profile chord. Presented results of the aeroelastic measurement correspond to the flow velocity M = 0.28 and Reynolds number 0.34·106. Time depends of the airflow forces and moments acting on the vibrating profile were obtained newly in this contribution. Applied method of the evaluation is now in the process of its evolvement, therefore presented results should be regards as preliminary conclusions.
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Influence of force transducer’s mounting on its signal
Půst, Ladislav ; Pešek, Luděk
Some records of dry-friction-properties measurement at oscillating relative motion were distorted owing to higher harmonics. Numerical simulation of simplified model of experimental set shows that this distorsion is caused by the interaction of dynamic properties of force transducer’s support. In the case when some harmonics of excitation dry friction force coincides with the any eigenfrequency of support. Using support with sufficiently high eigenfrequencies replaces this kind of distorsion.
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Implementation of 1D mathematical model of vocal cavities into TTS synthesizer – preliminary study
Radolf, Vojtěch ; Horák, Petr
Simplified 1D mathematical models of the human vocal tract were modified for using them in Text-To-Speech systems so that they help to simulate emotional speech. The geometry (area function) of the models for all Czech vowels was modified using the inverse task optimization procedure so that the computed formant frequencies match the measured formant frequencies of utterances of professional speaker. Output acoustic pressure signal generated from the models in wav format sounded satisfactorily for all the vowels and fundamental frequencies varied in an octave range from 77 Hz to 156 Hz. Neverthelles more testing procedures are needed to verify reliability and quickness of the model as well as intelligibility of generated utterances especially in formant TTS system and linear predictive TTS system.
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Measurement of contact stress in a self-oscillating model of human vocal folds
Horáček, Jaromír ; Bula, Vítězslav ; Veselý, Jan ; Radolf, Vojtěch
The contribution presents in vitro measurement of contact stress in the artificial vocal folds made of a silicon rubber excited by airflow with synchronous registration of the flow induced vocal fold vibrations using a high speed camera, measurement of subglottal dynamic and mean air pressure and the generated acoustic signal. The measured maximum impact stress, maximum glottal opening and sound pressure level are compared with data found in excised larynges as well as with the values numerically simulated by the aeroelastic model of vocal fold self-oscillations.
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