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The impact of plasma induced flow on the boundary layer in a narrow channel
Procházka, Pavel P. ; Uruba, Václav
The induced flow generated by dielectric barrier discharge (DBD) actuator working in steady and unsteady regime will be used to modify properties of naturally developer boundary layer (BL) in short and length rectangular perspex channel which is connected to the blow-down wind tunnel. The actuator is placed in spanwise configuration and the inlet velocities will range between 5 and 20 m•s-1. Previously, mean flow field and statistical quantities were subjugated to investigation. In this paper, there will be presented dynamical features of the BL as well as tracking of coherent structures using phase-averaging. Proper Orthogonal Decomposition (POD) of influenced flow field and frequency analysis will be presented. These results should be taken into account regarding to use in the flow around a bluff body.
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Experimental investigation of a control synthetic jet
Němcová, L. ; Kordík, Jozef ; Trávníček, Zdeněk ; Kopecký, V.
Synthetic jets were used in previous studies to control a continuous round air jet. This study focuses on the single synthetic jet, which is measured using Constant Temperature Anemometry (CTA) and Particle Image Velocimetry (PIV). Velocity profiles and frequency characteristics of the single synthetic jet are discussed and the velocity maps at frequencies of 30 Hz, 81 Hz and 190 Hz are presented. Finally, velocity, flow rate and momentum coefficients featured the present flow control are evaluated, and examples of actively controlled round air jet are put on. The results confirm efficiency of the present flow control method.
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Infrared Thermography as a Visualization Tool of Flow Control by Vortex Generators
Součková, Natálie ; Kuklová, J. ; Popelka, Lukáš ; Matějka, M.
This paper focuses on a suppression of the flow separation, which occurs on a deflected flap, by means of vortex generators (VG's). An airfoil NACA 63A421 with a simple flap and vane-type vortex generators were used. The investigation was carried out by using experimental and numerical methods. The data from the numerical simulation of the flapped airfoil without VG's control were used for the vortex generator design. Two sizes, two different shapes and various spacing of the vortex generators were tested. The flow past the airfoil was visualized through two methods, namely oil and infrared thermography visualization. The lift curves for both cases without and with vortex generators were acquired for a lift coefficient improvement determination. . The experiments were performed in closed circuit wind tunnels with open and close test sections. The improvement was achieved for several cases by means all of the applied methods.
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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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