|
| |
|
|
Small wind tunnel
Flídr, E. ; Šafařík, P. ; Trávníček, Zdeněk ; Broučková, Z.
The aim of this paper was to describe a small wind tunnel for flow field visualization. Flow velocity was investigated by four methods: hot wire anemometry, Prandtl tube, Pitot tube and flow field visualization were used. Flow pas circular cylinder in Von Kármán regime was shown.
|
|
|
Passive control of axisymmetric air flow
Pušková, P. ; Šafařík, P. ; Trávníček, Zdeněk ; Broučková, Z.
The work deals with passive management axially symmetrical air flow through the resonator. The aim is to see how it affects the behavior of the resonator current. To verify the theoretical knowledge is known experimentally measured frequency response of the Helmholtz resonator. It is also detected spectral power density signal from the microphone for various flow regimes (Re = 1600, 5000, 10000 and 30000) and various volumes of the resonator. For selected modes stream characteristics (speed decreases in the axis of flow and velocity profiles) are measured by Pitot probes. Then the flow characteristics are compared without a resonator and with resonator.
|
|
|
Experimental Investigation of The Flow Pattern Behind Cylinder
Vítkovičová, R. ; Skála, Vladislav ; Čížek, J.
Investigation of the flow behind bluff bodies, especially for cylinder, is one of the highly topical research topics in the fluid mechanics. Nevertheless, mainly because of its complexity, this topic is still an open problem. This article discusses the running project at the Czech Technical University in Prague, Faculty of Mechanical Engineering and it deal with the implementation of a methodology for measuring the cylinder wake in a wind tunnel and also recapitulates the partial results obtained measurements.
|
|
|
Optimized Five Hole Probe
Skála, Vladislav ; Pick, P. ; Nožička, J.
This work deals with the design, construction and setting characteristics pětiotvorové probe to measure the direction and speed of air flow in the wind tunnel. The probe was optimized in the design. Set characteristics will be used in the evaluation of the speed measured by the probe.
|
|
|
Solution of parameters of compressible viscous fluid flow through a minichannel
Hála, Jindřich ; Šafařík, Pavel ; Luxa, Martin
In this paper the results of the experiment of the choked air flow through channel with characteristic dimensions: height 2mm, width 100mm, length 100mm will be presented. On the bases of the both pneumatic and optical measurements the development of the flow properties along the channel and the influence of the dissipative processes will be described. The results of the experiment will be compared to the theoretical results and to the results of the numerical simulation. At the end the comparison will be thoroughly discussed.
|
|
|
Measurement of velocity and frequency in synthetic jet
Flídr, E. ; Šafařík, P. ; Trávníček, Zdeněk ; Broučková, Z.
The aim of this paper is to evaluate resonance frequency of pulsation in synthetic jets of air. Resonance frequency was determined by theoretical calculation. This frequency was compared with experimental results. To obtain frequency characteristics three experimental methods were used. Velocity was measured by Pitot tube and hot wire anemometry in CTA regime. Last method was based on calculation of reaction force from relative weight changes.
|
|
|
Spectral analysis of continual and synthetic jet
Broučková, Z. ; Trávníček, Zdeněk ; Šafařík, P.
This experimental work deals with a characterization of three types of air jet flows (continual jet, synthetic jet and continual jet which is controlled by a synthetic jet). The characterization is performed using the power spectral density (PSD). All the characteristics were obtained from single-point measurements of flow velocity. The velocity was measured by a hot-wire anemometer (CTA). Power spectral density was acquired directly from measured signal (or from velocity data) by means of MATLAB software. Obtained graphs showed the control effect on the main flow behaviour. The significant qualitative change was revealed near a boundary of synthetic jet formation. Moreover it was concluded that this significant change can be also well quantified.
|
|
| |
|
|
Visualization of the flow around rotating cylinder
Broučková, Z. ; Trávníček, Zdeněk ; Šafařík, P.
The visualization of the flow around a rotating and standing cylinder has been performed in air. This visualization has been performed for two velocities of a freestream for Reynolds numbers Re = 920 a 990 and for four frequencies of the rotation (0 s-1, 5 s-1, 12.5 s-1 and 20 s-1). The results have been compared with the theoretical model – potential flow. The velocity of the freestream has been evaluated by measurement of the frequency of the shedding vortices behind the standing cylinder in the regime of the Kármán vortex street. In the regime of the Kármán vortex street the Reynolds numbers were Re = 110 a 120. The known relations between Stouhal and Reynolds numbers were used.
|
guest ::
