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Influence of Carrying Frequency Phase Shift of Synthetic Jet Generator on The Noise
Pick, P. ; Matějka, Milan ; Skála, V.
The main topic of this article is the influence of phase shift of neighbouring synthetic jet generators to the flow field past a hump and noise reduction. Syntheetic jet generators are placed in the hump in front of point of boundary layer separation. The carrying frequency of actuating signal, wich is driving the synthetic jet generator, is shifted for about 180°. The modulated frequency, which corresponds to the shading frequency of the flow, is superposed on the carrying signal. Finally, the benefits of phase shift signal of neighbouring synthetic jet generators are described, as far as the produced noise and the total loss coefficient decrease are concerned.
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Numerical Solution of 3D Airflow in Channel Representing a Vocal Tract
Pořízková, P. ; Kozel, Karel ; Horáček, Jaromír
This study deals with the numerical solution of a 3D compressible flow of a viscous fluid in a channel for low inlet airfloe velocity. the channel is a simplified model of the glottal space in the human vocal tract. The system of Navier-Stokes equations has been used as mathematical model of laminar flow of the compressible viscous fluid in a domain. The numerical solution is implemented using the finite volume method (FVM)and the predictor-corrector MacCormack scheme with artifical viscosity using a grid of quadrilateral cells.
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Oblique Shock Wawes in Saturated Steam
Šimurda, David ; Nový, A. ; Šafařík, Pavel
The paper deals with modeling of oblique shock waves in saturated steam. A theoretical model is based on balance of mass, momentum and energy taking in account shock wave geometry. Numerical solution of steam parameters is performed using the IAPWS-IF97 steam thermodynamic properties. The aerodynamic calculation problem is formulated to solve oblique shock wave parameters for saturated steam upstream of the oblique shock. Achieved results are presented by means of hodograph shock polars and pressure-deflection shock polars and they are analyzed and discussed.
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Numerical Simulation of Compressible Transitional Flow Through High-Loaded Turbine Blade Cascade
Straka, P. ; Příhoda, Jaromír
The contribution deals with the numerical simulation of compressible transitional flow through the high-loaded turbine blade cascade. The mathematical model is based on the solution of the averaged Navier-Stokes equations closed by the explicit algebraic Reynolds stress model completed by the algebraic transition model taking into account the effect of free-stream turbulence and pressure gradient. The transition model is based on empirical correlations for the onset and the length of the transition region covering a wide range of free-stream turbulence. Various boundary conditions with the transition in attached and separated flows were tested and compared with experimental data.
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