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Bylo testováno mnoho typů mikrokapilár, čtvercových, kulatých a různých velikostí vnitřního průměru, ve kterých byla vytvořena kavitační bublina. Účelem těchto experimentů bylo sledovat rychlost rázové vlny těsně po počáteční kavitační bublině a odrazové vlny uvnitř i vně mikrokapilár. Hlavní metodou byla jiskra indukovaného limitu přehřátí kapaliny. Zde jsme použili metodu rozbití indukovanou laserem (LIB). Bylo popsáno nastavení kavitace, které ovlivňuje stabilitu a velikost bubliny. Pro snímání bublinek kavitace a rázové vlny jsme použili radiografické nastavení s kamerou. Byl pozorován časový vývoj rychlosti rázové vlny; rychlost počáteční rázové vlny uvnitř mikrokapiláry byla vyšší než rychlost rázu mimo mikrokapiláru.

An effective yet simple quantitative synthetic Schlieren imaging technique is presented in this paper. A multiplexed fringe pattern displayed on a common laptop screen is observed through a disturbed medium resulting in a change of the fringe pattern. Fourier analysis of such pattern provides high-resolution and almost real time measurement of rays’ deflection due to the medium refractive index variation. The developed technique was applied for measurement of a compressible fluid discharge from a narrow channel in a wind tunnel.

The blood flow in anomalous carotid bifurcation is associated with stroke. Changed character of the flow, especially the occurrence of vortex structures, has showed a high correlation with thrombus formation and the development of atherosclerotic changes. The purpose of this work is to perform comparative model measurements of the flow inside the internal carotid bifurcation and to evaluate the influence of the geometry - stenosis, aneurysm on changes in the interaction of the fluid with the wall surface, i.e. on the local hemodynamic. The study uses the Global Imaging Methods for visualization and measurement of the phantom blood flow. The evaluation of the measured dataset and their subsequent analysis confirms the impact on the origin and development of pathological changes.

The hydrodynamics and flow field were measured in an agitated vessel using 2-D Time Resolved Particle Image Velocimetry (2-D TR PIV). The experiments were carried out in a fully baffled cylindrical flat bottom vessel 400 mm in inner diameter agitated by a tooth impeller 133 mm in diameter. Distilled water was used as the agitated liquid. The velocity fields were investigated in the upward flow to the impeller for three impeller rotation speeds – 300 rpm, 500 rpm and 700 rpm, corresponding to a Reynolds number in the range 94 000 < Re < 221 000. This means that fully-developed turbulent flow was reached. This Re range secures the fully-developed turbulent flow in an agitated liquid. In accordance with the theory of mixing, the dimensionless mean and fluctuation velocities in the measured directions were found to be constant and independent of the impeller Reynolds number. On the basis of the test results the spatial distributions of dimensionless velocities were calculated. The axial turbulence intensity was found to be in the majority in the range from 0.4 to 0.7, which corresponds to the middle level of turbulence intensity.

Hydrodynamics and flow field were measured in an agitated vessel using 2-D Time Resolved Particle Image Velocimetry (2-D TR PIV). The experiments were carried out in a fully baffled cylindrical flat bottom vessel 400 mm in inner diameter agitated by a tooth impeller 133 mm in diameter. The velocity fields were measured in the impeller discharge flow for impeller rotation speeds from 300 rpm to 700 rpm and three liquids of different viscosities (i.e. (i) distilled water, ii) a 28% vol. aqueous solution of glycol, and iii) a 43% vol. aqueous solution of glycol), corresponding to the impeller Reynolds number in the range 68 000 < Re < 221 000. This Re range secures the fully-developed turbulent flow of agitated liquid. In accordance with the theory of mixing, the dimensionless mean and fluctuation velocities in the measured directions were found to be constant and independent of the impeller Reynolds number. On the basis of the test results the spatial distributions of dimensionless velocities were calculated. The radial turbulence intensity was found to be in the majority in the range from 0.3 to 0.9, which corresponds to the high level of this quantity.

The mixing of two immiscible phases is a process commonly seen in many branches of industry. Whether it be desirable (e.g. mixing of ingredients in chemical or food industry) or undesirable (e.g. sediments or contaminants in water purification) process, it has to be taken into consideration and a detailed description would be beneficial to any end product. This paper deals with a method for observing the volume ratio of two immiscible phases from the state of total separation, during the mixing process until the state of a homogenous mixture using industrial Electrical Impedance Tomography (EIT) system ITS p2+. The paper also shows a great agreement between the data obtained through measurement using this method and data derived from a theoretical formula. Also using EIT the authors were able to provide additional information describing the mixing process in real time.

In PIV studies published in the literature focusing on the investigation of the flow field in an agitated vessel the record time is ranging from the tenths and the units of seconds. The aim of this work was to determine minimum record time for PIV measurement in a vessel agitated by a Rushton turbine that is necessary to obtain relevant results of velocity field. The velocity fields were measured in a fully baffled cylindrical flat bottom vessel 400 mm in inner diameter agitated by a Rushton turbine 133 mm in diameter using 2-D Time Resolved Particle Image Velocimetry in the impeller Reynolds number range from 50 000 to 189 000. This Re range secures the fully-developed turbulent flow of agitated liquid. Three liquids of different viscosities were used as the agitated liquid. On the basis of the analysis of the radial and axial components of the mean- and fluctuation velocities measured outside the impeller region it was found that dimensionless minimum record time is independent of impeller Reynolds number and is equalled N.tRmin = 103 ± 19.

In this paper a three-dimensional reconstruction of flow field behind flat plate representing a wing is presented. The reconstruction is always performed for pair of 2D vector maps obtained by 3D PIV with two cameras which record measurement area from different locations. Three-dimensional reconstruction can be obtained in various ways. This paper summarizes two: the reconstruction based on the known correspondences and the reconstruction based on the knowledge of intrinsic and extrinsic parameters of cameras. The methods can be used in the cases when it is impossible to use a calibration pattern or when reconstruction by commercial software fails.

The hydrodynamics and flow field were measured in an agitated vessel using 2-D Time Resolved Particle Image Velocimetry (2-D TR PIV). The experiments were carried out in a fully baffled cylindrical flat bottom vessel 400 mm in inner diameter agitated by a Rushton turbine 133 mm in diameter. The velocity fields were measured in the zone in upward flow to the impeller for impeller rotation speeds from 300 rpm to 850 rpm and three liquids of different viscosities (i.e. (i) distilled water, ii) a 28% vol. aqueous solution of glycol, and iii) a 43% vol. aqueous solution of glycol), corresponding to the impeller Reynolds number in the range 50 000 < Re < 189 000. This Re range secures the fully-developed turbulent flow of agitated liquid. In accordance with the theory of mixing, the dimensionless mean and fluctuation velocities in the measured directions were found to be constant and independent of the impeller Reynolds number. On the basis of the test results the spatial distributions of dimensionless velocities were calculated. The axial turbulence intensity was found to be in the majority in the range from 0.388 to 0.540, which corresponds to the high level of turbulence intensity.

Stereo PIV measurements has been performed behind the inclined plate, angle of attack 5 and 10 deg. Occurrence and dynamics of streamwise structures behind the plate trailing edge have been studied in details using POD method. The streamwise structures are represented by vortices and low- and highvelocity regions, probably streaks. The obtained results support the hypothesis of an airfoil-flow force interaction by Hoffman and Johnson [1,2].

The paper describes a holographic method for vibration analysis in nanometer range. The method was successfully applied on different types of piezoelectric transformers and the measurement results are introduced. To proof the reliability of the method it was done a comparing simultaneous measurement of a piezoelectric component by the holographic method and the well-established single-point interferometric method. Results showing the minimal deviation of both methods are presented in the final part of the paper.

The paper describes experimental research of the flow impinging on heated plate. The flow was generated by synthetic jet actuators. Construction of these actuators is designed to excite a fluid flow in the circulatory track.

Synthetic jets were used in previous studies to control a continuous round air jet. This study focuses on the single synthetic jet, which is measured using Constant Temperature Anemometry (CTA) and Particle Image Velocimetry (PIV). Velocity profiles and frequency characteristics of the single synthetic jet are discussed and the velocity maps at frequencies of 30 Hz, 81 Hz and 190 Hz are presented. Finally, velocity, flow rate and momentum coefficients featured the present flow control are evaluated, and examples of actively controlled round air jet are put on. The results confirm efficiency of the present flow control method.

The work deals with the experimental investigation of turbulent flow in a closed channel with the backward-facing inclined step. Experiments were carried by means of the PIV optical measuring method in the channel of the rectangular cross-section in the inlet part and with inclined steps of the constant height H mm and various inclination angles for a wide range of the Reynolds number. The attention was paid especially to the separation region behind the step and to the relaxation of the shear layer after the reattachment in the outlet part of the channel. The dependence of the length of the separation region on the Reynolds number was obtained for various step angles. Optical measurements were completed by the measurement of static pressure distribution in the inlet and outlet part of the channel to estimate energy losses.

This article presents the results of temperature measurements in a real model of heat exchanger using LIF method. By the help of fluorescent dye Rhodamine B that responsive on the temperature variation is visualized the rate and warming - up of the liquid above the heating pipe. The drift excited by heat convection is measured by PIV method. The results of temperature field measurements are compared with metering affected by temperature probe.

The spray analysis is a fundamental for many industrial applications. The knowledge of spray distribution, the spray geometry and structures is crucial. Recommended here is the method of simultaneously measuring the droplet size, spray geometry and impact droplet velocity. Referred here is the Interferometry particle sizing technique applied on a full cone nozzle with external feeding. The spray was examined in three stages: close to the nozzle exit, in 0.7m and 1.7m distance far from the nozzle exit and under pressure 1.3, 2.7 and 3.5 bar.

The subject of study involves the handling of liquids and gases in the order of micro-litres and in micro scale resolution. Microfluidic structures are very fine in the context of the macro world, and standard dimensions are around 100 µm, but even finer, depending on the manufacturing process. Visualization are used to study events and processes inside microstructures. Events taking place in fine structures are influenced by parameters such as liquid resistance, interfacial forces, diffusion transfer of molecules and mutual interactions both at the chemical and thermodynamic levels. The analysis of the behaviour of liquids in microfluidic systems involves a change of approach in deriving the influence of input conditions on the resulting behaviour and the course of interactions both between the wall of the structure and the liquid, but also in the liquid itself. The methodology and production of a microfluidic device usually uses a number of technologies. The process often combines a lithographic technique with a controlled etching or laser engraving method. This article introduces the initial experiments with droplet microfluidic generators, which took place at TUL - CXI and subsequently led to the construction of your own implementation in the form of a capillary chip that can be used in pharmacy.

Studying the behavior of the rock mass is essential for developing a geophysical monitoring system, which allows continuous timelapse monitoring of the state of the rocks environment. For example, rock mass monitoring might be a crucial part of a system for storing dangerous, especially nuclear waste in a geological environment. The goal of this project is developing a working system for long-term timelapse monitoring of a geological environment using non-destructive geophysical techniques. The monitoring system works with geoelectrical and seismic properties of the hard-rocks environment. The system carries out 4D monitoring of the rock properties behavior in the close vicinity of an underground excavation. For the initial experimental measurements, two geophysical methods were chosen - electrical resistive tomography (ERT) and ultrasonic microseismic. The ERT method uses a set of 48 stainless electrodes 20 cm apart (9.4 m length of the profile in total) and the frequency of the measurements is six hours (i.e., four measurements per day). Currently the seismic uses frequency of five minutes between gathering one seismic record. Attention is paid to the behavior of a significant fracture located in the middle of the measuring system. The monitoring device collects data that are being sent via the LAN connection to the project members' computers. [ABSTRACT FROM AUTHOR]

Cavitation bubbles generated via laser-induced breakdown are investigated experimentally. The present work focuses on the direction of the first bubble collapse near a solid surface in distilled water. The solid surface is placed first to the right side in a cuvette filled with distilled water and then placed to the top of the cuvette. In this experiment, it is observed in which direction the cavitation bubble collapses. The cavitation bubble is visualized by a high-speed camera of frequency 68kHz.