Wake flow past an ALUTEC profile

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 location. We studied the wake past the profile of 45 mm side. We studied the topology of the wake in the dependence on the angle of attack by using the Particle Image Velocimetry technique

Turbulence topology behind different sections of the wind turbine blade

This work aimed to investigate the turbulence characteristics behind different parts of the wind turbine blade. Airfoils S807, S813, S817, and S803, which characterize the shape of the blade at different lengths, were selected for estimation. During the experiment, the chord-based Reynolds number was 2.6×105, while the angle of attack was zero. Measuring crosssections were placed behind the trailing edge at x·c-1≈0.2, 0.4 and 1.0. For the determination flow topology, we used a Hotwire anemometry with a split fiber probe 55R55 and a miniature X-wire probe 55P64. The obtained data allowed us to determine and compare the evolution of the wake behind different types of airfoils in streamwise and spanwise directions. Thus, the largest and smallest velocity deficit located behind S817 and S803 airfoils, respectively. This trend is also evident in the Normalized Reynolds shear stress distributions. Finally, we determined the spectrum and calculated the Integral length scale, the Taylor and Kolmogorov microscale of turbulent flow. According to the results, profile S817 contributes to the formation of a flow with a large scale of turbulence, while the S803 is contrary

Vorticity statistics in the near wake of asymmetric prismatic airfoil NACA 64-618 at negative angle of attack –10° at Reynolds numbers 1.6 ⋅ 104 and 1.6 ⋅ 105 in distance 0.0 – 0.4 × chord past trailing edge measured by Particle Image Velocimetry

The airfoil NACA 64-618 is realized by using two levels of quality: first the theoretical profile is printed on a 3D printer in a direct, “naive” way, this geometry has been scanned by using 3D scanner and based on the deviations, a better model has been processed. The flow within the turbulent wake is measured by using Particle Image Velocimetry (PIV) technique at two velocities separated by one order of magnitud

Preliminary results of PIV measurement past a stator wheel inside the VT-400 test turbine

The feasibility study of Particle Image Velocimetry (PIV) measurements inside a test turbine at the University of West Bohemia. The current VT-400 turbine is not prepared for optical measurement with seeding particles, thus several technical issues had to be addressed until low-quality data were obtained only at low speed of 2000 RPM (rounds per minute). Even the low quality data are able to show the fluctuation anisotropy or the size of fluctuation structures, which are quantities not measurable by classical pressure methods

Structural Deformation of a Running Wind Tunnel Measured By Optical Scanning

Nowadays, the development of wind tunnels for the study of various aerodynamic phenomena is actively developing. It is possible to generate a highly laminar flow only under the condition of structural stability of the construction parts of the wind tunnel under the action of sharp pressure drops. The aim of this research is to investigate the deformation and displacement of the structural parts of the developed wind tunnel capacity of 55 kW depending on the velocity of the generated airflow. To estimate the amount of deformation and mutual displacement of the structural elements of the wind tunnel depending on the airflow velocity, we used the ARAMIS optical system

Structural Deformation of a Running Wind Tunnel Measured By Optical Scanning

Nowadays, the development of wind tunnels for the study of various aerodynamic phenomena is actively developing. It is possible to generate a highly laminar flow only under the condition of structural stability of the construction parts of the wind tunnel under the action of sharp pressure drops. The aim of this research is to investigate the deformation and displacement of the structural parts of the developed wind tunnel capacity of 55 kW depending on the velocity of the generated airflow. To estimate the amount of deformation and mutual displacement of the structural elements of the wind tunnel depending on the airflow velocity, we used the ARAMIS optical system

Analysis of instability generation of photovoltaic power station

We showed an analysis of installed capacity and annual electricity generation of photovoltaic power stations in the world and Ukraine. The main focus of our research was on the analysis of the influence of meteorological factors on power generation. Two photovoltaic power stations of two types (terrestrial and rooftop) located in Ukraine were selected for the study. We used Spearman's rank correlation to estimate the impact of meteorological factors on solar power generation

Užití systému ARAMIS pro měření strukturální stability aerodynamického tunelu za běhu

Wind tunnels are popularly used to study various aerodynamic phenomena. Their design significantly influences the quality of the created airflow. During the flow generation, the construction parts of the wind tunnel to get deformed due to pressure variations. This phenomenon significantly complicates the creation of high-level laminar flow and worsens the results of experimental studies. The main purpose of this work is to investigate the effect of a sharp change in flow velocity on the structural stability of parts of a wind tunnel with a capacity of 55 kW. For experimental studies, we used the ARAMIS optical measurement system. Using it, we estimated the amount of deformation and mutual displacement of parts of the running wind tunnel at a flow rate of 76 m·s-

Expanding the PIV Spectral Range and the Turbulence Generated by Grid of Prismatic Circular Cylinders

The grid turbulence past a grid made of row of prismatic circular rods (rod diameter = 10 mm, rod spacing = 20 mm) perpendicular to the flow is observed by using a pair of PIV cameras. The first one has field of view larger (81 mm), the second one smaller (31 mm), which increases the dynamical range, where the spectral turbulence properties can be explored. Energy spectra displays usual behavior approximately following k −5/3 law, the anisotropy originates at larger scales and the flatness describing strong rare events is connected with smaller scales. The spectral properties of vorticity do not collapse due to the different lengthscale of differentiation, which make questionable the previous research based on the vorticity statistics. Research background: Grid turbulence is the best experimentally accessible prototype of ideal homogenous and isotropic turbulence, although it is known, it is not exactly the ideal one. Purpose of the article: This contribution explores the possibility of expanding the limited dynamical range of PIV method. Methods: Particle Image Velocimetry is based on observing the motion of small particles carried by the flow. Findings & Value added: Anisotropy connected with large scales, flatness with small scales; it does not work for vorticity