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Oblast parametrů syntetizovaných proudů
Broučková, Z. ; Šafařík, P. ; Trávníček, Zdeněk
Práce uvádí prehled parametru, které jsou potrebné pro popis syntetizovanýchproudu. Jsou diskutovány prípady vybrané z dostupné literatury. Rovnež je overenaspolehlivost nekolika známých kritérií existence techto proudu. Vetšina kritérií má obdobnýcharakter a dává spolehlivé výsledky – všechny vybrané prípady je splnují. Jedno zposuzovaných kriterií bylo vyhodnoceno jako málo duveryhodné.Dále bylo provedeno merení rychlosti proudení osove symetrického syntetizovaného prouduPitotovou sondou a anemometrem se žhaveným drátkem. Výsledky merení velmi dobrevyhovují poznatkum z literatury. Navíc se ukázalo, jak snižování Reynoldsova císla apribližování pracovního bodu ke kritické hodnote na hranici oblasti existence vede kpostupnému zkracování dosahu proudu.
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“Master and Slave" Fluidic Amplifier Cascade
Tesař, Václav
Paper díscusses mutual matching of two no-moving-part fluidic unvented amplifiers in a two-device module, where small MASTER device, with feedback loop converting it into a small high-frequency oscillator dictates the flow switching in a large powerful SLAVE device. Interest in this configuration was caused by it providing a solution in generation of gas microbubbles. The oscillation frequency has to be high and this calls for small amplifier size - while a the total gas flow has to be large, calling for a large size. The conditions in the circuit is complicated by the need to considerfive terminals in each amplifier.
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Visualization of synthetic jets at higher stokes numbers
Broučková, Zuzana ; Trávníček, Zdeněk ; Šafařík, Pavel
Visualization of synthetic jets at higher Stokes numbers (S = 90 and 127) by the phase-locked smoke-wire technique is presented and discussed. The working fluid is air. The Reynolds numbers are quantified using hot-wire anemometry. Although our method of visualization essentially provides only qualitative results, the present study also demonstrates some quantitative results, namely the behavior of the zero-net-mass-flux jet near its critical stage. Visualization of the sub-critical stage is also shown.
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Experimental Data on High-Speed Flow Past the Root Blade Cascade
Šimurda, David ; Luxa, Martin ; Synáč, J. ; Šafařík, P.
The paper deals with experimental results of high-speed aerodynamic research on a blade cascade. The blade cascade represents root section of the last stage rotor blades of large output steam turbine. Basic aerodynamic characteristics of the blade cascade are presented together with photographs of flow fields in the range of transonic flow regimes. Results are analysed and discussed to provide a new knowledge on design and operation of the last rotor at the region of the blade root.
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Experimental investigation of synthetic jet array
Dančová, Petra ; Vít, Tomáš ; Kotek, M.
Paper deals on an experimental investigation of a synthetic jet array. This investigation focuses on a partial problem of the general task “a synthetic jet array interacting with a channel flow”. The experiments have been performed with water as a working fluid using hot-wire anemometry, laser Doppler vibrometry and particle image velocimetry methods.
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The interaction of continual and synthetic jets
Broučková, Zuzana ; Trávníček, Zdeněk ; Šafařík, Pavel
This work deals with an interaction of continual and cross synthetic jets. Both jets are axisymmetric. All measurements have been performed in air by means of the Pitot tube and hot-wire anemometry. Flow visualization has been also performed. The possibility of flow control is shown and quantified. For the moderate momentum ratio, the mean jet deflection reasonably agrees with the momentum conservation.
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BASIC CHARACTERISTICS OF ARRAY OF PULSATILE JET
Novotný, P. ; Vít, Tomáš ; Vestfálová, M.
The presented paper shows the results of measurement of basic characteristics of array of pulsatile jets which are used to enhance the efficiency of ejectors. Four pulsatile jets forms cross like structure where perpendicular couples are operating in two basic modes (a) in phase and (b) in antiphase. Paper presents phase averaged velocity profiles and velocity fields. All of the presented experiments are realized using hot wire anemometry method.
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