Daniel Duda
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View article: Wake Turbulence Induced by Local Blade Oscillation in a Linear Cascade
Wake Turbulence Induced by Local Blade Oscillation in a Linear Cascade Open
This paper investigates the oscillatory effect of a single blade on the turbulence wake downstream of a low-pressure turbine cascade. Experimental investigations were conducted at a chord-based Reynolds number of 2.3×105 with an excitation…
View article: Vortices in the wake past adjustable car spoiler in open and closed configuration studied experimentally by PIV
Vortices in the wake past adjustable car spoiler in open and closed configuration studied experimentally by PIV Open
A complex adjustable car spoiler opens or closes in dependence on ride properties: the closed state increases negative lift (better for curves), while the open state ensures lower drag (better for straight segments of the road). Both these…
View article: Experimental Exploration of Quasi-2D Turbulence Clamped by Boundary Layers
Experimental Exploration of Quasi-2D Turbulence Clamped by Boundary Layers Open
View article: Hot-Wire Investigation of Turbulent Flow over Vibrating Low-Pressure Turbine Blade Cascade
Hot-Wire Investigation of Turbulent Flow over Vibrating Low-Pressure Turbine Blade Cascade Open
This paper presents experimental results on unsteady turbulent flow in a low-pressure turbine blade cascade, specifically exploring the effects of blade vibrations on wake topology and turbulence structure. The study focused on comparing t…
View article: EffectofSingleBladeVibrationonWake Turbulence in a Linear Cascade
EffectofSingleBladeVibrationonWake Turbulence in a Linear Cascade Open
The present research examines the impact of isolated blade oscillations on the turbulent flow structure in a linear blade cascade. The study was carried out at a Reynolds number of 2.3 × 10⁵ with blade vibrations induced at 73 Hz. Addition…
View article: Flow through a hexagonal mixing grid with parabolic vanes measured experimentally by PIV in two planes at distances 1 and 5 × the maximum inscribed diameter D at Reynolds number based on D of 1.5⋅10<sup>4</sup>, 3.1⋅10<sup>4</sup> and 6.2⋅10<sup>4</sup>
Flow through a hexagonal mixing grid with parabolic vanes measured experimentally by PIV in two planes at distances 1 and 5 × the maximum inscribed diameter D at Reynolds number based on D of 1.5⋅10<sup>4</sup>, 3.1⋅10<sup>4</sup> and 6.2⋅10<sup>4</sup> Open
Particle Image Velocimetry (PIV) method is used to measure the flow through a prototype mixing grid for nuclear reactor. In this preliminary experiment, there are no fuel rods, the grid is empty. We observe the pattern of jets and wakes, w…
View article: PIV measurement of model nuclear fuel rod bundle
PIV measurement of model nuclear fuel rod bundle Open
The fuel rods are kept in their positions by using spacer grids . This grid is sometimes connected with mixing grid , which mixes the fluid between the fuel rods in order to enhance the heat transfer. One of the possible configurations is …
View article: PIV Measurement of Wakes Past Stator Wheel Inside Air Test Turbine VT-400 in Two Axial×Tangential Planes
PIV Measurement of Wakes Past Stator Wheel Inside Air Test Turbine VT-400 in Two Axial×Tangential Planes Open
VT-400 is a single-stage test turbine working with ambient air located at the University of West Bohemia in Pilsen.Inside this turbine, we perform a PIV (Particle Image Velocimetry) measurement of the flow field in two planes oriented in a…
View article: Interaction of stream-wise vortices generated by swirler grid
Interaction of stream-wise vortices generated by swirler grid Open
A system of stream-wise vortices has been created using a grid of swirling elements with alternating orientations (like a chessboard). The particle image velocimetry method has been used to map the velocity field in several planes perpendi…
View article: Wakes and secondary structures past stator wheel in test turbine VT-400 observed by PIV
Wakes and secondary structures past stator wheel in test turbine VT-400 observed by PIV Open
Flow inside the axial test turbine VT-400 is measured by using a standard methodology of Particle Image Velocimetry (PIV). The studied area lies between the stator and rotor wheel in meridional plane. This area covers both: the regular flo…
View article: PIV measurement of near shear layer of a circular jet
PIV measurement of near shear layer of a circular jet Open
The shear layer (SL) of a turbulent jet is studied by using Particle Image Velocimetry (PIV) up to distance 0.2 nozzle diameters in axial × radial plane. The jet is generated by circular nozzle at Reynolds numbers 1.1·10 5 to 1.1·10 6 . Th…
View article: Numerical simulation of the flow topology over NREL’s S807 airfoil at different models of turbulence
Numerical simulation of the flow topology over NREL’s S807 airfoil at different models of turbulence Open
Current numerical simulations investigate subsonic flow around the NREL’s S807 airfoil without an incident angle at Reynolds numbers near 2.8∙10 5 . This work is devoted to the assessment application of various turbulence models for a nume…
View article: On Streamwise Vorticity Dynamics in a Wake
On Streamwise Vorticity Dynamics in a Wake Open
The streamwise vortices are detected experimentally in the wake behind a circular cylinder in Reynolds number 5 thousand on the top of Kármán vortex street dynamics. The stereo time-resolved PIV method has been used to detect the wake and …
View article: Roughness density effect on turbulent boundary layer evolution
Roughness density effect on turbulent boundary layer evolution Open
This work aimed to investigate the boundary layer topology over various densities of roughness. For experiments, we used three different surface conditions comprised of rectangular elements with uniform height arranged in staggered rows an…
View article: Turbulence organization in isolated roughness flow
Turbulence organization in isolated roughness flow Open
The primary goal of this investigation was to analyze the specific evolution of the boundary layer over an isolated roughness. A specific surface consisting of rectangular elements of the same height arranged in a checkerboard pattern was …
View article: The effect of eroded leading edge to the turbulent wake topology studied by PIV
The effect of eroded leading edge to the turbulent wake topology studied by PIV Open
The effect of leading edge erosion to the flow is studied experimentally by standard method of Particle Image Velocimetry. Three airfoil models are manufactured: the reference one, the homogenously eroded one, which is modeled by putting a…
View article: The concept, approach and benefits of energy auditing and its impact on the environment
The concept, approach and benefits of energy auditing and its impact on the environment Open
The electricity industry plays an irreplaceable role in the rise of the economic potential and development of every country around the world. The international community of industry, research institutions and global businesses focuses more…
View article: On Velocity Spectra within the Wake behind a Circular Cylinder
On Velocity Spectra within the Wake behind a Circular Cylinder Open
The canonical case of a circular cylinder in crossflow is studied experimentally at Reynolds number 5k. The power-spectra of all velocity components in the turbulent wake are studied in detail. Special attention is paid to the appearance o…
View article: Vortex profiles in grid turbulence observed by PIV
Vortex profiles in grid turbulence observed by PIV Open
Grid turbulence is often thought to be a prototype of isotropic and homogeneous turbulence of Kolmogorov style. There is no some single vortex dominating the flow, rather there is lot of vortices distributed along the Richardson cascade. T…
View article: Wakes and Secondary Structures Past Stator Wheel in Test Turbine Vt-400 Observed by Piv
Wakes and Secondary Structures Past Stator Wheel in Test Turbine Vt-400 Observed by Piv Open
View article: On Dynamics of Flow past a Stage Axial Air Turbine
On Dynamics of Flow past a Stage Axial Air Turbine Open
The air flow inside a single-stage test turbine is studied experimentally using the Particle Image Velocimetry technique. The measurements were performed at the axial-tangential plane just behind the rotor at the middle blade radius. The l…
View article: Strouhal number and vortices in far wake of cylinder
Strouhal number and vortices in far wake of cylinder Open
The wake past a smooth cylinder perpendicular to the flow is studied 15 D (cylinder diameters) downstream by using particle image velocimetry (PIV). Spatial shedding period is used to estimate the spatial Strouhal number (Sh) and to compar…
View article: Estimation of the Induced Incidence of a High Reaction Axial Turbine Bucket
Estimation of the Induced Incidence of a High Reaction Axial Turbine Bucket Open
This paper describes the effect of the incidence angle of the bucket on the performance of the axial turbine stage. The off-design operating conditions of the turbine stage result in a change in the velocity diagrams. This results in a pos…
View article: Experimental and Numerical Study on Vortical Structures and Their Dynamics in a Pump Sump
Experimental and Numerical Study on Vortical Structures and Their Dynamics in a Pump Sump Open
Research on water flow in a pump inlet sump is presented. The main effort has been devoted to the study of the vortical structures’ appearance and their behavior. The study was conducted in a dedicated model of the pump sump consisting of …
View article: Searching of Individual Vortices in Experimental Data
Searching of Individual Vortices in Experimental Data Open
The turbulent flows consist of many interacting vortices of all scales, which all together self-organize being responsible for the statistical properties of turbulence. This chapter describes the searching of individual vortices in velocit…
View article: Hot-Wire Investigation of Turbulence Topology behind Blades at Different Shape Qualities
Hot-Wire Investigation of Turbulence Topology behind Blades at Different Shape Qualities Open
The scope of this paper is to perform a detailed experimental investigation of the shape error effect on the turbulence evolution behind NACA 64-618 airfoil. This airfoil is 3D-printed with predefined typical shape inaccuracies. A high-pre…
View article: Effect of Manufacturing Inaccuracies on the Wake Past Asymmetric Airfoil by PIV
Effect of Manufacturing Inaccuracies on the Wake Past Asymmetric Airfoil by PIV Open
The effect of manufacturing geometry deviations on the flow past a NACA 64(3)-618 asymmetric airfoil is studied. This airfoil is 3D printed according to the coordinates from a public database. An optical high-precision 3D scanner, GOM Atos…
View article: Wake flow past an ALUTEC profile
Wake flow past an ALUTEC profile Open
Aluminum construction profiles become a standard construction material for short-term stands in science and in industry as well. It has the shape of square prism with an groove in each side to easy connecting the nut or bolt in any locatio…
View article: Effect of Cylinder Roughness on Strouhal Number
Effect of Cylinder Roughness on Strouhal Number Open
The main goal of this paper is to establish a better understanding of the relationship between a Strouhal number and surface roughness. Hot-wire anemometry was used to evaluations the characteristics of turbulent flow behind circular cylin…
View article: Drag Estimation in the Near Wake of the NREL's Airfoils Based on Hot-Wire Data
Drag Estimation in the Near Wake of the NREL's Airfoils Based on Hot-Wire Data Open
This paper presents the results of the drag coefficient estimations for different types of NREL airfoils based on the experimental data. Namely, it was S803, S807, S813, and S817 profiles with the same chord length. The investigations were…