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Interaction and Feedbacks 2011
Zolotarev, Igor
Proceedings INTERACTION AND FEEDBACKS 2011 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 self-excited vibration of the isolated profile in wide interval of Mach numbers
Vlček, Václav ; Kozánek, Jan ; Zolotarev, Igor
In this paper the experimental results of the self-excited vibration of the isolated NACA0015 profile in subsonic airflow are given. The optical and pneumatical methods were used in the wide range of flow velocities (Mach numbers 0,18 – 0,45). The profile was equipped with semi-conductor pressure sensors situated in the profile surface. From obtained interferograms and pressure signals follow complicated relation among phase differences of rotational and transversal profile movement.
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Temperature processes at dry friction
Pešek, Luděk ; Půst, Ladislav ; Cibulka, Jan ; Bula, Vítězslav
Application of dry friction damping contact is very often used for damping of turbine blades vibration. This problem is intensively studied in our Institute for several years, but the deficiency of knowledge of special material’s friction characteristics introduces serious uncertainty into the results of research. Therefore laboratory experimental equipment has been designed and realized. Results of the first set of measurement is presented and discussed. Friction double of steel blade material and overlay of tungsten carbide was investigated at various thrust forces and frequencies of relative motion at the simultaneous measurement of temperatures in tree points near the friction surface. Increase of temperature after 25 s of friction run, friction coefficient, friction force, dissipated energy in one cycle, during 1 s, entire energy during the friction run, lost power, and energy for 1oC temperature increase at various conditions were ascertained.
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Analysis of the influence of piriform sinus on vocal tract acoustic characteristics
Radolf, Vojtěch
An analysis of several testing mathematical models and human vocal tract model with piriform sinus (PS) cavities was done. The method used was based on 1D acoustic wave equation, considering viscous losses, radiation impedance losses and applied on conical elements in frequency domain. The analysis revealed that the 1D model is able to capture differences in acoustic variables of the vocal tract modified with PS. Nevertheless the model includes PS of very small dimensions (9 mm in depth) that generate spectral changes far away from frequency band 4-5 kHz as Dang&Honda (1996) observed with their models including PS up to 20 mm in depth.
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