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Visualisation via video recording was carryed out in a Ranque-Hilsch vortex tube with a square cross-section. Video files were captured at recording speeds from 1000 to 10 000 frames per second. The best video files were obtained at a shooting frequency of 7600 frames per second with an input pressure of 1 bar. The video confirmed the presence of a double helix in the flow core in the second section of the tube. The video files showed the presence of a circulation zone between the flow core and the periphery, which is constantly changing over time. It can be clearly seen the angle at which the particles move in the peripheral flow.

The aim of the work was to develop a laser Doppler anemometry method for high-speed turbulent aerodynamic flow diagnostic. As a result, this allowed us to measure two projections of the velocity vector in the range of 0.1 - 400 m/s with a relative error not exceeding 0.5%. The measurement area was 0.1x0.1x0.5mm. The positioning device moved the measuring unit in the area of 250 x 250 x 250 mm with an accuracy of 0.1 mm. This method also provides the ability to measure local flow rate fluctuations.

The complex method of ultrasonic diagnostics of two-phase flows in a liquid metal medium is developed. It allows measuring the dynamic and structural characteristics of the floating inhomogeneity. A software and hardware complex that implements the proposed method is developed and tested for ultrasonic diagnostics of two-phase flows in water and liquid metal medium.

The aim of the work is to develop a laser Doppler anemometry method for diagnosing turbulent aerodynamic flows in the near wall region. This will enable measuring two projections of the velocity vector in the range of 0.001 … 400 m/s with a relative error not exceeding 0.1%. The measurement area is 0.1×0.1x0.5mm. The positioning device allows moving the measuring unit in the area of 250×250x250 mm with an accuracy of 0.1 mm. This method also provides the ability to measure local flow rate fluctuations.

This work aims at creating a universal software package for the development and testing of triangulation methods using structured lighting for measuring the three-dimensional geometry of objects in difficult ambient lighting conditions. As a result, a software package meeting the stated requirements is created. Lighting is based on the Fong model. A method for preloading objects is implemented to optimize the operation of the software package. An accelerated method for creating shadow maps is proposed and implemented. The developed software package is shown to successfully perform all required functions.

Current work is devoted to the development of a device for monitoring the dynamic shape of a power unit. The work is based on the FMCW method. The light source uses a low-coherence semiconductor laser diode. Signal processing is performed on an adapted Doppler processor. The paper describes the methods, hardware and signal processing algorithms.

In this work, a method for physicochemical and biological optical studies of the nanoparticles size distribution is developed. Its implementation in the LAD-079 spectrometer is described. The distinctive features of the LAD-079 spectrometer include the following. Multi-angle parallel measurements of static and dynamic light scattering, scattering angle from 0–180 degrees. Probing at three wavelengths with the ability to analyze the polarization activity of the sample (488 nm, 532 nm, 650 nm). Programmable precision thermostat with an error less than 0.1 °C in the range 0 ÷ +80°C with the possibility of building and software implementation of the experiment plan. Robust monobloc design of the spectrometer that does not require adjustments and a special optical table. The ability to measure the size of dispersed nanoparticles in low-transparent liquids.

The work continues the work of the previous year. The mass transfer characteristics were experimentally analyzed in a rotary-divergent flow with inserted blades. The laser Doppler anemometer was used for turbulent mass transfer diagnostics. The experimental investigation was used to verify the numerical calculations. As in previous year the model of Reynolds stress transfer describes the flow in range of flow rates from 50 to 250 n.m3/h more adequately than the Spallart-Almares turbulence model.

In the field of fundamental metrology and ensuring the unity of measuring instruments, the role of optical information methods, systems and technologies of non-contact diagnostics of dynamic processes is extremely relevant. The profiles of the axial velocity component were measured in the working section of the secondary standard test rig for air flow speed. The flow kinematics inside the working section is studied using a laser Doppler anemometer (LDA) with an adaptive temporal selection of the velocity vector (LAD-08).

The sea spray, a typical feature of the marine atmospheric boundary layer, is one of the most uncertain factors among those controlling hurricanes and severe storms. To investigate how extremely strong winds tear off spray from wave crests, to classify such events, and to quantify the efficiency of the disclosed mechanisms, the high-speed wind-wave flume was constructed. For development of understanding of spray formation under hurricane wind condition the information about velocity distribution is required. The flow kinematics inside the wind-wave was studied using a laser Doppler anemometer (LDA) with an adaptive temporal selection of the velocity vector (LAD-08).

The analysis of current complex experimental investigation of the vortex tube with square cross section is made focusing on the criticality of the inner flow in the framework of the flow crisis concept. The criticality condition is proved to take place in the vortex tube by operating with LDA obtained velocity experimental data. As the measured axial velocity exceeds the calculated velocity of centrifugal elastic waves on the boundary between the longitudinal circulation zone and the near wall swirling jet, two scenarios are supposed possible for the transition of the supercritical state to a subcritical one, similar to the vortex breakdown in a swirling jet at its discharge into the quiet liquid volume: the mild oscillations or a series of hydraulic jumps become possible, leading to a flow pattern choke change with the transformation to heat of excess kinetic energy.

The work continues the work of the previous year. The mass transfer characteristics were experimentally analyzed in a rotary-divergent flow with inserted blades. The laser Doppler anemometer was used for turbulent mass transfer diagnostics. The experimental investigation was used to verify the numerical calculations. As in previous year the model of Reynolds stress transfer describes the flow in range of flow rates from 50 to 250 n.m3/h more adequately than the K-e turbulence model.

This problem can arise in mechanics, chemistry and catalysis in the mass transfer intensification. The mass transfer characteristics were experimentally analyzed in a controlled rotary-divergent flow. The laser Doppler anemometer was used for turbulent mass transfer diagnostics. The experimental investigation was used to verify the numerical calculations. The numerical simulation has shown the presence of a near-wall jet after a rotary device and the reverse flow zones formation. The model of Reynolds stress transfer adequately describes the flow in range of flow rates from 50 to 250 n.m3/h. The Spallart-Almares turbulence model fails to adequately describe the flow at all flow rates.

The complex technique using laser and video equipment in test conditions at the setups of the Laboratory of water turbines of the Leningrad Metal Plant has been developed to conduct laser measurements of velocity fields and video recording of cavitation phenomena based on the integration of the laser systems (“LAD - 0xx" and “Track-07 S”), created at the Kutateladze Institute of Thermophysics SB RAS (IT SB RAS) and JSC “IOIT.” The Doppler anemometer allowed to achieve experimental distribution of the circumferential, axial, and radial velocity components at each point along the radius of the suction tube cone section of test experimental setup which has give information about vortex structure in suction turbine. The developed PTV method is described. The investigation of cavitation behind the turbine blade at test setup at velocities of 8-10 m/s is presented.

The fundamental scientific problem of this kind arises in mechanics, chemistry and catalysis in the intensification of mass transfer. The turbulent mass transfer characteristics were analyzed experimentally in a controlled rotational-divergent flow. The laser Doppler anemometry was used for turbulent mass transfer diagnostic. The verification of numerical calculations by computational hydrodynamics has been carried out according to the results of experimental studies. Calculation of turbulent kinematic is build on solving of a system of continuity and the Navier-Stokes equations. The fluid is incompressible and isothermal. For averaged equations closure, semi-empirical turbulence models were used: the k-ε model of turbulence and the Reynolds stresses transfer model. The calculation has showed the existanceof a near-wall jet after a rotating device and the generation of reverse flow zones. Comparison with experimental data has shown that all models of turbulence adequately model the rotational-divergent flow only until the formation of flow gaps and the formation of reverse flow zones. The discrepancy with the experiment occurs while controlling the flow to equalize the velocity profiles.

The work is devoted to experimental investigation of the vortex effect in the Ranque-Hilsch tube using non-contact methods. The vortex tube, which consists of the slit-type swirler made as accelerating vortex chamber, a working channel with a square cross section, a radial diffuser at the hot outlet and a diaphragm at the cold one was used. For optical diagnostics, the vortex chamber (swirler) was equipped with optical windows. On the basis of measurements by the laser Doppler anemometry method, new experimental information about flow at the entrance of the Ranque-Hilsch vortex tube was obtained.

Such fundamental scientific problem arises in much industrial application. The turbulent fluid dynamic characteristics were analyzed experimentally in a rotary-divergent flow. The laser Doppler anemometry was used for turbulent mass transfer diagnostics. The verification of numerical calculations by computational hydrodynamics has been carried out according to the results of experimental studies. Verification has shown that turbulent models describe the rotational-divergent flow well only until generation of flow gaps and formation of recirculation zones.

The aim of the present paper is to obtain a better understanding of wakes generated by 2, 3 and 4 elements (disks and/or rotors) modeling an array of wind turbines in a wind farm. We here extend the results from our previous experimental model studies on the correlation between the behavior of the wake behind dual configurations of passive disks and active rotors to establish new knowledge regarding the wake development behind the 3rd and 4th rotor operating in a wake. To accomplish this, 2D PIV velocity measurements were carried out to investigate the flow properties upstream and downstream the tested rotors and discs in the array. The study also provides measured values of power and thrust coefficients of the model turbines using strain gauges installed directly on the rotors. The aim of the laboratory experiment is to provide data to calibrate and validate wake models for design and analysis arrays of wind turbines located in wind farms.

This study focused on the large-scale vortex structures. The working section was a tangential vortex chamber with a cylindrical cross-section. The flow was swirled by tangential supply of fluid into the chamber, using 12 direct-flow rectangular nozzles. The design swirl parameter was equal to 6.6 and was determined based on the vortex chamber geometry. The Reynolds number was maintained equal to 30000. Quantitative measurements were realized with the use of the optical technique of laser Doppler anemometry. The results of optical measurements allowed determining main parameters of the vortex core for two basic modes of the vortex flow, including the central direct-flow vortex and the spiral vortex.

Longitudinal and tangential components of the mean velocity field inside the Ranque tube of square cross section are presented for a central longitudinal section. Measurements are carried at central plane over the entire tube, with 1-2 millimeter step in transverse direction and with 10 millimeter step along the tube. The data is presented in the form of velocity maps.

This experimental work is aimed at investigating the self-similarity of the local axial vorticity and azimuthal velocity in the tip vortices core in the wind turbine rotor wake. In the current work, the averaged local axial vorticity and azimuthal velocity profiles of the tip rotor vortex were measured. These profiles were tested to a self-similarity and compared with the Lamb-Oseen vortex.

This paper is devoted to experimental investigation of the interaction between the pair of precessing vortices in a tangential vortex chamber. The test section was the tangential vortex chamber with a cylindrical working area. The liquid was tangentially fed into the chamber through 12 rectangular nozzles. The swirl parameter varied in the range 0 ÷ 6.6, and the Reynolds number varied within 6000 ÷ 52000. On the basis of visualization materials the dependence of the precession frequency of the system of two vortices was obtained. For the quantitative investigation the optical methods of laser Doppler anemometry (LDA) and the Particle Image Velocimetry (PIV) were used. Information about vortices and recirculation zones was obtained from the optical measurements.

Obstacles like forests, ridges and hills can strongly affect the velocity profile in front of a wind turbine rotor. The present work aims at quantifying the influence of nearby located obstacles on the performance and wake characteristics of a downstream located wind turbine. Here the influence of an obstacle in the form of a cylindrical disk was investigated experimentally in a water flume. A model of a three-bladed rotor, designed using Glauert's optimum theory at a tip speed ratio λ = 5, was placed in the wake of a disk with a diameter close to the one of the rotor. The distance from the disk to the rotor was changed from 4 to 8 rotor diameters, with the vertical distance from the rotor axis varied 0.5 and 1 rotor diameters. The associated turbulent intensity of the incoming flow to the rotor changed 3 to '6% due to the influence of the disk wake. In the experiment, thrust characteristics and associated pulsations as a function of the incoming flow structures were measured by strain gauges. The flow condition in front of the rotor was measured with high temporal accuracy using LDA and power coefficients were determine as function of tip speed ratio for different obstacle positions. Furthermore, PIV measurements were carried out to study the development of the mean velocity deficit profiles of the wake behind the wind turbine model under the influence of the wake generated by the obstacle. By use of regression techniques to fit the velocity profiles it was possible to determine velocity deficits and estimate length scales of the wake attenuation.

The flow behind the model of wind turbine rotor is investigated experimentally in a water flume using Particle Image Velocimetry. The study carried out involves rotors of three bladed wind turbine designed using Glauert's optimization. The transitional regime, generally characterized as in between the regime governed by stable organized vortical structures and the turbulent wake, develops from disturbances of the tip and root vorticies through vortex paring and further complex behaviour towards the fully turbulent wake. Our PIV measurements pay special attention to the onset of the instabilities. The near wake characteristics (development of expansion, tip vortex position, deficit velocity and rotation in the wake) have been measured for different tip speed ratio to compare with main assumptions and conclusions of various rotor theories.