|
|
Měřicí řetězec aerodynamického profilu se dvěma stupni volnosti
Štěpán, M. ; Šidlof, P. ; Vlček, Václav
Příspěvek je zaměřen na měření vibračního pohybu aerodynamického profilu v aerodynamickém tunelu Ústavu termomechaniky AV ČR. Fyzikální model NACA 0015 profilu byl navržen a vyroben, umožňuje pohyb se dvěma stupni volnosti: vertikální pohyb a otáčení kolem elastické osy. Pohyb profilu byl registrován optickým inkrementálním čidlem, nezávisle též vysokorychlostní kamerou se synchronním měřením tlaků na povrchu profilu. Zesílené signály ze snímačů tlaku a tenzometrů byly získány pomocí datových karet National Instruments a Dewesoft měřícího programu. Výsledky měření jsou zde uvedeny.
|
|
| |
|
| |
|
| |
|
|
Records-distortion at discontinuous forces measurements
Půst, Ladislav ; Pešek, Luděk ; Radolfová, Alena
Our paper in the last “Interaction and feedback 2012” conference has been oriented on the influence of force transducer’s mounting on its signal. The presented paper links on the previous contribution and concentrates on the problem of recording time histories of discontinuous periodic forces. The frequency spectrum of sudden jumps in force courses contain many high components, some of them can be laying near to some of the system’s eigenfrequencies. The excitation of these higher oscillations can essentially distort records of force jumps. Unfortunately, the application of low pas filter cannot be used, as it deletes both distorted frequencies as well as these same frequencies in the jumps signal and distorted it again. One of the possibilities how to solve this problem is using special evaluation procedure that enables to estimate (at least approximately) the real measured force. This evaluation method can be used successfully at measurement of dry friction forces arising during vibration’s tangential contact.
|
|
|
Measurement of acoustic input impedance of the human vocal tract models
Radolf, Vojtěch ; Dlask, P. ; Otčenášek, Z.
Input acoustic impedance of the human vocal tract models made of plexiglass was measured using the measurement system BIAS 6. Three models A, I, U for vowels /a:/, /i:/ and /u:/ had simplified rectangular shape of the channel with constant height 20 mm. The fourth model A2D had elliptical channel shape. Resulted resonance frequencies were within the known ranges of formant frequencies of the vowels. The resonances of default configurations varied for different boundary positions in relation to measuring microphone in the range of 0.5 %, 3.9 %, 2.1%, 6.7 % for the models A2D, A, I and U, respectively. The resonances of direct and reversed models with the output closed differed in the range of 0.5 % and 1.8 % for A2D and A model, respectively. The measured and computed resonances differed in the range from 3.8 % for A2D to 14.6 % for the model I.
|
|
|
Numerical solution of compressible subsonic flows in 3D channel
Pořízková, P. ; Kozel, K. ; Horáček, Jaromír
The channels shape is a simplified geometry of the glottal space in the human vocal tract. Goal is numerical simulation of flow in the channels which involves attributes of real flow causing acoustic perturbations. The system of Navier-Stokes equations closed with static pressure expression for ideal gas describes the unsteady laminar flow of compressible viscous fluid. The numerical solution is implemented using the finite volume method and the predictor-corrector MacCormack scheme with artificial viscosity using a grid of quadrilateral cells. The unsteady grid of quadrilateral cells is considered in the form of conservation laws using Arbitrary Lagrangian-Eulerian method.
|
host ::
RSS.