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Actuators for Flow Control Based on Plasma Principle
Procházka, Pavel P. ; Uruba, Václav ; Šonský, Jiří
One can distinguish between two types of flow control, passive and active. Active flow control has a few advantages. The biggest advantage is a possibility to influence the flow only if there is a need. By contrast, the passive control acts all the time and for all regimes and this is not good in terms of fuel consumption, for example. Active flow control provides the necessary momentum to the shear layer from an external source, as opposed to passive control which uses the momentum of free stream of fluid.
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Numerická simulace aerodynamické interakce křídla a trupu
Šimurda, David ; Popelka, Lukáš ; Zelený, L. ; Matějka, Milan
In order to investigate and understand extent of the wing-body interaction effects taking place during operation of a particular self-launching sailplane, commercial code Fluent 6.3 was used for numerical simulation of flow past a simplified model of TST-10a. Several methods were used to identify vortex structures originating due to interference effects in this part of the aircraft. 3D effects and distortions of pressure and velocity distributions taking place in the junction of the body and the fuselage were observed.
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Dynamika odtržení řízené mezní vrstvy na válci
Uruba, Václav ; Matějka, Milan ; Procházka, Pavel
Dynamical aspects of the boundary layer separation on a circular cylinder in cross-flow are studied experimentally. Two cases are compared, the base case and the case with excitation using a synthetic jet actuator. The TR-PIV technique was used to catch both space and time velocity field correlations. Instantaneous velocity fields and skin friction distributions are evaluated. For dynamical structures study, the BOD method was applied based on energetic principle. Dynamical modes connected with vortex shedding process, dynamical excitation by synthetic jet and transition to turbulence are identified.
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Dynamics of a boundary layer separation
Uruba, Václav ; Knob, Martin
Dynamical behavior of a boundary layer separation is studied using experimental approach. The dynamical nature of the phenomenon is demonstrated on a simple case of a boundary layer in adverse pressure gradient. The Time-Resolved PIV technique was utilized to study instantaneous structure of the separation region and its time development. Distinctive coherent structures and their dynamical behavior were identified using the POD and BOD methods.
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Měřicí prostor pro profily a tělesa, studie proveditelnosti výzkumného projektu
Popelka, Lukáš
Article describes new 865x485x900mm3 test section of closed-circuit wind tunnel IT AS CR for airfoils and bodies, respectively. These setups are arranged primary for three-component aerodynamic balance and visualization techniques access. Prepared research programme aimed at reference measurements, outer stream turbulence, flow control and surface roughness influence on boundary layer transition and separation is presented.
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Aplikace ortogonálních dekompozičních metod
Uruba, Václav ; Knob, Martin
Orthogonal decomposition techniques are introduced with respect to application to time-resolved PIV data. Several modifications of the techniques are taken into account, particularly the Proper Orthogonal Decomposition in continuous and snapshot variants for space analysis only as well as the Bi-Orthogonal Decomposition to be used for joint space-time analysis.
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