National Repository of Grey Literature 247 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Flow in Branched Channel
Uruba, Václav ; Procházka, Pavel P. ; Skála, Vladislav
Flow in a branched channel is investigated experimentally using the PIV method. The branches are issuing from the main cannel perpendicularly, all channels are of rectangular cross-section. The time-mean flow-fields in the main channel and in the branches are studied in details.
Measurement of Turbulence in LP Part of the 1090 MW Steam Turbine
Antoš, Pavel ; Uruba, Václav ; Jonáš, Pavel ; Procházka, Pavel P. ; Skála, Vladislav ; Hoznedl, M. ; Sedlák, K.
The aim of the paper is to demonstrate a use of the hot-wire anemometry for measurement of turbulent fluctuation in a steam turbine. Measurement technique and used methods are presented in the paper. An experimental research was performed in the last stage of LP (lowpressure) part of the 1090 MW steam turbine in nuclear power-plant turbine. The last moving steel blade has a length of 1220 mm. The experiment was carried out by Institute of Thermomechanics of Czech Academy of Science (IT CAS) in cooperation with Doosan Škoda Power s.r.o. (DSPW), the manufacturer of the turbine.
The Experimental Study of Aeroelastic Coupling of the Moveable Blade Grid with the Flow Field at Reynolds Number up to 150 000
Procházka, Pavel P. ; Uruba, Václav ; Pešek, Luděk ; Bula, Vítězslav
This experimental study was conducted to help clarify an aeroelastic coupling in the case of rotational periodic bodies. The blade grid was placed behind the outlet of the blow-down wind tunnel. Three of five blades were constructed to allow vertical position changing by the action of three shakers. Particle Image Velocimetry was used to study the flow field statistical and dynamical parameter. The parameters, whose presence indicates the aeroelastic coupling, are searched.
On 3D Structure of Wake Behind an Inclined Plate
Uruba, Václav ; Procházka, Pavel P. ; Skála, Vladislav
The flow-field behind an inclined plate was investigated experimentally using stereo PIV method providing all 3 velocity vector components in the measuring plane. Flow structure in several measuring planes perpendicular to the main flow was studied. Statistical characteristics were evaluated in the measuring planes. The downwash angle was assessed as well to consider its effect on the lift generation mechanism. The dynamical behavior was studied using Proper Orthogonal Decomposition of velocity fields in measuring planes. The dominant (most energetic) structures were evaluated and presented. The detected structures are of the form of streamwise vortices combined with high-and low-velocity streaks.
Flow field of the valve model II
Uruba, Václav ; Procházka, Pavel P. ; Skála, Vladislav
This report is dealing with the measurement on the second valve model. It builds on the previous report. The main goal of this investigation was to describe the physical principles related with the non-stationarities which are related with the stability of shear layers of the flow field inside the valve.
Flow field of the valve model I
Uruba, Václav ; Procházka, Pavel P. ; Skála, Vladislav
This report is dealing with the measurement on the valve model. The model design is based on the real steam turbine valve used for steam regulation in an inlet pipe. The main goal of this investigation was to describe the physical principles related with the non-stationarities which are related with the stability of shear layers of the flow field inside the valve.
Numerical and experimental investigation of parallel flows in the branched channels
Novotný, Jaroslav ; Uruba, Václav ; Procházka, Pavel P. ; Skála, Vladislav
The flow filed inside a main channel with 13 parallel outlets was investigated numerically and also experimentally by PIV method. The formulas were derived and a program in Fortran programming language was introduced to solve turbulent flow described by N-S equations and by various models of turbulence. K-epsilon model without wall functions is the best match with the experiment. \n\n
Pod analysis of stereo PIV data from wake behind an inclined plate
Uruba, Václav ; Procházka, Pavel P.
The motivation of the experiments is to study the flow dynamics and topology behind an airfoil. The airfoil is modeled by a simple flat plate with rounded leading and trailing edges. To obtain an information about the 3D structure of the flow the stereo PIV method is applied in the plain behind the plate oriented perpendicularly to the main flow. The flow dynamics topology could be studied using POD method revealing the most energetic fluctuation topologies. The POD is typically applied on a 2-component vector fields. In the presented paper the POD will be used for 3-component vector field resulting from the stereo PIV method.
The experimental study of aeroelastic coupling of the moveable blade grid with the flow field at Reynolds number up to 150 000
Procházka, Pavel ; Uruba, Václav ; Pešek, Luděk ; Bula, Vítězslav
This experimental study was conducted to help clarify an aeroelastic coupling in the case of rotational periodic bodies. The blade grid was placed behind the outlet of the blow-down wind tunnel. Three of five blades were constructed to allow vertical position changing by the action of three shakers. Particle Image Velocimetry was used to study the flow field statistical and dynamical parameter. The parameters, whose presence indicates the aeroelastic coupling, are searched.
Urban Ventilation Dependence on Geometric Configuration
Kukačka, Libor ; Jaňour, Zbyněk (advisor) ; Carpentieri, Matteo (referee) ; Uruba, Václav (referee)
Title: Urban Ventilation Dependence on Geometric Configuration Author: RNDr. Ing. Libor Kukačka Department: Department of Atmospheric Physics Supervisor: prof. RNDr. Zbyněk Jaňour, DrSc., Academy of Sciences of the Czech Republic, Institute of Thermomechanics, v. v. i. Abstract: The main goal of the thesis is to investigate the impact of urban geometry on the urban ventilation using wind-tunnel modelling. To measure the pollutant transport, both advective and turbulent, within complex urban geometries with a high temporal resolution a special measurement method was developed. At first, the pollution of a simplified urban area was simulated by a ground-level point source and the ventilation of the intersection with respect to four wind directions was studied. Later, the pollution of other simplified and complex urban areas was simulated by a ground-level line source and the ventilation of three different street canyons with respect to wind direction perpendicular and oblique to their along-canyon axis was investigated. The clear impact of urban complexity and wind direction on street canyon ventilation is demonstrated at lateral and top openings of all investigated canyons and the intersection. Whilst the dominance of the pollutant advection is demonstrated at the eaves of pitched roofs, at the roof ridges...

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