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Řízení vztlaku a odtržení na lopatkách vetrných elektrárenúčinkem vírů majících osy orientované ve směru proudění
Tesař, Václav ; Kordík, Jozef ; Daněk, Martin
Paper describes two alternative versions of wind-turbine blade section models for tests in wind tunnel aimed at lift control at high angles of attack. They use synthetic jet (or hybrid-synthetic jet) exiting at 18 % of the chord length on the upper (suction) surface. Otherwise the two layouts are different. In version A the single synthetic jet issues from a continuous exit slit across the full span. In the other version B, a large number of small hybrid-synthetic jets exit in an anti-parallel manner (180 deg phase shift between neighbours) from a row of orifices, switched by an array of small fluidic valves inside the model. Rather surprisingly, despite the differences, the lift control in both layouts was found to be due to generation of vortices with streamwise orientation of their axes.
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Piezokeramický generátor pro syntetizovaný proud
Dančová, P. ; Vít, T. ; Trávníček, Zdeněk
Synthetic jets are jets of fluid which are generated by periodic pulzations of fluid. The pulsation generator can work on principle of loudspeaker, piston, pieocrystal or the other equipment. In our experiments, the actuator works on piezoceramic transducer (PTC). The paper shows results of vibrometry principle and results of FEM simulations.
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Syntetizovaný proud
Dančová, P. ; Trávníček, Zdeněk ; Vít, T.
Equipments working on the synthetic jet (SJ) principle can be used in aerospace industry, automotive industry, pumps and ejectors, cooling and heating applications, intensification of mixing in chemical reactors. SJ can be used for jet control and vectoring, flow control in external and internal aerodynamics, intensification of heat transfer. The main advantage of these applications is relative simplicity of SJ equipment. This article summarizes primary SJ world studies, and it shows examples of own experimental results.
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Použití fluidiky k řízení proudění syntetickými proudy
Tesař, Václav
Synthetic jets and a special variant, the hybrid synthetic jets with non-zero nozzle exit time mean flow rate are applied to flow control pas an airfoil. Paper describes their generation on suction side at 18% chord by fluidic devices built into a wind tunnel model of an airfoil NACA 63-418.
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Přestup tepla a hmoty u syntetizovaného impaktního proudu
Trávníček, Zdeněk ; Hyhlík, Tomáš ; Maršík, František
A zero–net–mass–flux actuator was used to generate a synthetic air jet. The local mass transfer in the jet impingement configuration was investigated using the naphthalene sublimation method. Based on the heat/mass transfer analogy, the mass transfer data have been converted to the corresponding heat transfer data. The results have been compared with the data for continuous impinging jets; the difference is less than 11%.
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Numerická simulace a vizualizace vytváření syntetizovaného proudu
Trávníček, Zdeněk ; Vogel, Jiří ; Vít, T.
The paper presents the results of numerical and experimental investigations of a synthetic jet generation. The experiments were performed in air by means of flow visualization and hot-wire anemometry. The subsequent numerical simulation was performed using the commercial code FLUENT. The geometry, boundary conditions, and material properties of the numerical simulation were defined according to the real experimental situation.
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