This work presents the results of numerical modeling of Karman vortex street generation performed with ANSYS/FLUENT package application. The influence of the mechanical elements located downstream of the bluff body on the vortex frequency has been found during earlier laboratory investigations. Five various geometrical configurations have been tested. Considerable differences in pictures of distributions of pressure, horizontal and vertical velocities have appeared for various configurations. Qualitative as well as quantitative results are presented in the paper. They confirm the significant dependence of the Karman vortex street parameters on the meter configuration.

A description of direct simulation of crosswind loads caused by critical vortex excitation and the response of the structure to these loads are presented in this paper. Tower-like structures of circular cross-sections are considered. A proposed mathematical model of vortex excitation has been numerically implemented and a selfserving computer program was created for the purpose. This software, cooperating with the FEM system, allows for a simulation of a crosswind load and lateral response in real time, meaning that at each time step of the calculations the load is generated using information regarding displacements seen beforehand. A detailed description of the mathematical model is neglected in this paper, which is focused on numerical simulations. WAWS and AR methods are used in simulations.

Knowledge of the fluid dynamic characteristics in a stirred vessel is essential for reliable design and scale-up of a mixing system. In this paper, 3D hydrodynamics in a vessel agitated by a Rushton turbine were numerically studied (with the help of a CFD computer program (CFX 13.0)). The study was carried out covering a wide Reynolds number range: 104 - 105. Computations, based on control volume method, were made using the k-ε model. Our main purpose was to investigate the effect of vessel configuration and agitation rates on the flow structure and power consumption. Three types of vessels were used: unbaffled, baffled and a vessel with slots placed at the external perimeter of its vertical wall. The effect of slot length has been investigated. The comparison of our predicted results with available experimental data shows a satisfactory agreement.

This paper is devoted to the problem of the appearance of a stagnation region during Karman vortex shedding. This particular phenomenon has been addressed by G. Birkhoff in his model of vortices generation. Experimental results obtained by various research methods confirm the existence of a stagnation region. The properties of this stagnation region have been described based on experimental findings involving flow visualisation and hot-wire anemometry. Special attention has been paid to the relationship between the existence of a slit in the bluff body and the size of the stagnation region. The slit takes over the role of the stagnation region as an information channel for generating vortices.

The converging-diverging structure is introduced to extend the lower limit of measurement of vortex flowmeters. As a compact device, the converging-diverging vortex flowmeter is proposed and designed, and its performance is studied experimentally. It is found that, first of all, an up to 51% extension of the lower measurement limit can be realized through the converging-diverging structure, compared with conventional vortex flowmeters; second, the converging-diverging vortex flowmeter with a trapezoidal bluff body has a larger Strouhal number and smaller pressure loss. The results suggest that the converging-diverging vortex flowmeter provides an alternative device especially suitable for the measurement of low-velocity fluids.

This paper discusses design, evaluation, and application for the use of swirl/vortex technologies as liquid purifi cation system. A study was performed using modifi ed swirl sedimentation tanks. The vortex separators containing baffle have been studied under laboratory conditions at hydraulic load from 21 to 64 [m3/(m2·h)]. Analyzed disperser phases were municipal water and glycerol solutions of varying concentration. The pressure drop and the efficiency of purification of liquid stream were analyzed. The suspended particles of different diameters were successfully removed from liquid with the application of swirl chambers of proposed constructions. It was found that damming of liquid in the tank increases alongside liquid stream at the inlet and depends on the tank construction. The efficiency of the sedimentation tanks increases alongside the diameters of solid particles and decrease in the liquid flow rate. The best construction proved to be the one where baffle is located in the middle of in- and outlet due to the highest efficiency of the purification liquid stream for solid particles of the smallest diameter. The proposed solution is an alternative to the constructions of heavy fraction separators.

A comparative analysis of filtration performance of tangential and axial inlet reverse-flow cyclone separators and vortex tube separators is presented. The study showed that vortex tube separators are characterized by a quality factor q several time higher than tangential inlet reverse-flow cyclone separators. The cyclone separators yield low separation efficiency and low filtration performance at low air flow rates at low air volumes aspired by the engine at low speed. One of the well-known and not commonly used methods to improve separation efficiency is to apply electric field. An original design of a vortex tube separator with insulators generating electric field in the area of aerosol flow is presented. High voltage was applied to the cyclone separator housing and its swirl vane. A special method and test conditions were developed for cyclone separators with electric field. Separation efficiency, filtration performance and pressure drop across the cyclone separator in two different variants were determined. The tests were carried out at five inlet velocity of cyclones υ₀  = 1.75; 3.5; 7.0; 10.5; 14 m/s at an extraction rate of m₀  = 10%, and at an average dust concentration in the inlet air of
s = 1 g/m³. Using the electric field in the area of a swirling aerosol stream resulted in an increase (over 12% – φ_c  = 96.3%) in separation efficiency at inlet velocity of cyclone ranging from 1.75 to 3.5 m/s. An increase in separation efficiency at other inlet velocity of cyclone is minor and does not exceed 3‒4%.