Swirling Jet Research Articles

Heat transfer characteristics of a turbulent swirl jet issuing from a circular nozzle

Experimental and numerical studies on the flow field and cooling performance of a swirling jet, impinging on a flat surface is presented. A new nozzle that resembles the swirl injector of a liquid propellant rocket engine is used. This study considers different parameters including swirl number(S), Reynolds number(Re), normalised orifice to target spacing (Z/D) and confinement. The performance of various RANS and LES turbulence models is assessed using the data obtained from present experimental studies and that reported in literature. RNG k-ϵ turbulent model is successful in predicting heat transfer in non swirling flow. In the case of swirling flow, LES WALEM(Wall Adapting Local Eddy viscosity Model) predicts the heat transfer better than the other models. The performance of Swirling Impinging Jets(SIJ) and Cylindrical Impinging Jets (CIJ) is compared. At higher Z/D, introduction of swirl results in reduction in heat transfer and this is because of the increased spreading of the jet and reduction in velocity of the jet impinging on the target. Better performance is achieved at lower Z/D when a cylindrical jet is introduced with a small amount of swirl. For Z/D = 2 and S = 0.2, the peak Nu increases by 10 % and average Nu in the stagnation region increases by 6 % in comparison to CIJ. The position of the peak Nu moves away from the axis of the jet and there is better uniformity in Nu in the stagnation region. For Z/D = 2 swirling flow creates secondary peak(which usually occurs at high Re)even at low Re. At very low Z/D, top wall confinement causes increase in both peak heat transfer and average heat transfer in the stagnation region.

Global Stability and Forced Response Analysis of Swirling Flows In Aviation Combustors

Abstract Swirling jets are canonical flow fields used to stabilize flames in many gas turbine combustion systems. These flows amplify background acoustic disturbances and perturb the flame, producing combustion noise and potentially combustion instabilities. Hydrodynamic flow response to acoustic excitations in reacting flows is an important modeling task for understanding combustion noise and combustion instabilities. This study utilizes a global hydrodynamic stability analysis in a Bi-Global and Tri-Global framework to model the vortical hydrodynamic modes of a reacting, swirling LES mean flow based on a commercial nozzle. After conducting an unforced, natural Bi-Global stability analysis to study the unstable eigenmodes of the flow, linearized equations of motion are used to study flow response of the flow to forcing. An empirical velocity transfer function is constructed by determining the flow response to a harmonically varying 150-1500 Hz u' velocity disturbance at the inflow boundary. These disturbances are strongly amplified, with amplification factors ranging from about 20 to 50 and peaking at about 1050 Hz, or st = 0.375. A comparison study with a cartesian, three-dimensional reacting base flow is also performed where the base-flow varies spatially in three-dimensions. The study utilizes a stable, high accuracy, but computationally effective centered finite difference scheme based on a three-dimensional structured mesh. Illustrative results present the qualitative modes and quantitative transfer functions for Bi-Global and Tri-Global stability analyses.

A novel dual swirling air curtain dust-control system: Design and similar experiment

The excessive concentration of dust in fully-mechanized excavation face (FEF) poses a serious risk to the health and safety of workers. This paper proposes a novel dual swirling air curtain (DSAC) dust-control system and conducts similar experiments to evaluate its effectiveness. Firstly, the theory of annular swirling jet and the dust-control mechanism of DSAC are elaborated upon. The subsequent section presents a comprehensive description of the proposed DSAC, outlining its design and the theoretical computations involved. Thereafter, the formation and attenuation of the air curtain, as well as the dust diffusion patterns with and without the DSAC system, are investigated using a similar experimental platform. The results showed that the DSAC can produce a clockwise rotating swirling air curtain. Furthermore, the utilization of the DSAC can effectively mitigate dust concentration on the experimental platform and suppress dust diffusion.

Influence of the swirl vanes in convergent-divergent nozzle on screech tones and mixing efficiency at subsonic and supersonic jet flow

PurposeThe purpose of this study is to investigate the effect of coaxial swirlers on acoustic emission and reduction of potential core length in jet engines.Design/methodology/approachThe swirlers are introduced in the form of curved vanes with angles varied from 0° to 130°, corresponding to swirl numbers of 0–1.5. These swirlers are fixed in the annular chamber and tested at different nozzle pressure ratios of 2, 4 and 6.FindingsThe study finds that transonic tones exist for the nonswirl jet, creating an unfavorable effect. However, these screech tones are eliminated by introducing a swirl jet at the nozzle exit. Weak swirl shows a greater reduction in noise than strong swirl at subsonic conditions. In addition, the introduction of swirl jets at all pressure ratios significantly reduces jet noise and core length in supersonic conditions, mitigating the noise created by shockwaves and leading to screech tone-free jet mixing.Originality/valueThe paper provides valuable insights into the use of coaxial swirlers for noise reduction and core length reduction in jet engines, particularly in supersonic conditions.

On the effect of axial inlet angle on the droplet size distribution and mixing uniformity for swirl jet mixer at high phase ratios

The “short pass” problem of liquid-liquid two-phase mixing at high phase ratios limited the development and applications of jet mixer in industrial process. In this study, the effect of the axial inlet angle on the mixing characteristics of a swirl jet mixer was investigated through laser particle size analysis and computational fluid mechanics (CFD) coupled with population balance model (PBM). The result was shown that as the axial inlet angle increased, the dispersed phase droplet sizes decreased, and the droplet size distribution was widened for the fixed mixer configuration. At Re ≤ 3.000×104, tangential inlet was more conducive to improving mixing uniformity. Conversely, the axial inlet angle of 90° was optimal at Re ≥ 3.750×104. Numerical simulations revealed that the tangential inlet effectively intensified liquid-liquid interactions, including streamlines extension, increased vorticity, improved droplet size uniformity. Additionally, the increase of the axial inlet angle resulted in increased turbulence stress and shortened decay period, the reduction in droplet size, and a wide droplet size distribution. The research findings can serve as theoretical basis for the hydraulic design and promoted applications of swirl jet mixers.

Experimental and numerical study of combined impinging jets at low nozzle-plate distance for confined and unconfined impingement plate

This study investigates the heat transfer and flow dynamics of combined impinging jets at low nozzle-plate distances. The combined jets comprise (i) circular and quadruple helical jets and (ii) circular and double helical jets. A conventional jet is generated from the only circular part of the combined jet. Experiments are conducted with a constant total flow rate (Qt = 85 LPM) and low nozzle-plate distances (H/D = 0.1, 0.2, 0.3, 0.4) for confined and unconfined jet cases. Flow rate ratios (Q*=0.176, 0.235, 0.352, 0.588, 0.823) are used for different swirl intensities. A numerical study was performed using ANSYS Fluent software. The results show that the numerical analysis is consistent with the experimental research. The combined impingement jet shows a potential to improve the low heat transfer occurring at the stagnation zone at low nozzle-plate distance in the swirl jet, leading to non-uniform heat transfer. The confined jet case at the low nozzle-plate distance reduces the heat transfer at the stagnation point and over the entire plate as regards the unconfined jet case. Increasing the H/D distance in the combined impinging jet improves the heat transfer in the confined jet case but reduces it in the unconfined case. Correlations are given for heat transfer prediction depending on H/D and Q* for unconfined and confined cases of the combined jet. Increasing the flow rate ratio and the nozzle-plate distance increases the heat transfer uniformity for the confined and unconfined jet cases. In contrast, the unconfined jet case is better regarding heat transfer uniformity. The confinement plate creates a negative pressure on the impingement plate in all conditions. In contrast, the unconfined jet case is precisely the opposite.

Confinement effect on recirculation structures in isothermal coaxial swirling jet

The present experimental work reports first observations of effect of confinement on recirculation structures in non-reacting coaxial swirling jet in geometric swirl number range of SG= 2.14–2.88. In particular, particle image velocimetry (PIV) has been employed to study the effect of two confinement ratios (CR) viz. 1.82 and 2.73 on two types of recirculation zones (RZ) i.e., pre-breakdown dual rings (PVB) and central toroidal recirculation zone (CTRZ) observed in coaxial swirling jet. It is observed thatCR = 1.82 produces a slight radial expansion in PVB whereas significant compaction and streamwise elongation is observed in CTRZ. The difference in the observation is explained on the basis of modified Rossby number (Rom). The PVB flow state which is characterised byRom > 1 presents significant resistance to wall effect to be felt till the centerline. Contrarily, the CTRZ flow mode characterised byRom < 1allows the wall effect to be felt till the centerline, in turn affecting the RZ entirely. TheCR = 2.73 is shown to offer larger area for the RZ to spread radially outwards. Resultantly, the PVB and CTRZ are shown to significantly widen. Other significant comparisons betweenCR = 1.82 and 2.73 for PVB and CTRZ are elaborated using contour plots of axial and radial strain rates.

An experimental study of the flow structure in arrays of cold bidirectional swirling jets

Jets arrays have become a promising technology for industrial applications, including heat transfer and combustion processes. This paper presents the first experimental results of arrays of bidirectional swirling jets, including their flow structures and specific turbulent interactions. Particle image velocimetry of non-reacting linear arrays showed the formation of recirculation zones within each jet of the array. These regions are the most stable, with fluctuations less than 0.002 of the bulk inlet velocity Vin. In addition, jets merging locations also show a significant decrease in velocity fluctuations, with values V′/Vin &amp;lt; 0.005, which is most clearly seen at a smaller pitch distance. However, the highest turbulent fluctuations occur in shear layers, reaching values of V'/Vin ≈ 0.02 for linear arrays and V'/Vin ≈ 0.03 for planar configurations. The flow structure of planar arrays is more complex, leading to the formation of secondary vortex structures at locations of jet interaction. This results in a significant decrease in the flow swirl number, from an initial value of Sin = 2.1 in the vortex chamber, to S1 = 0.36–0.49 at z/dout2 = 1 and S2 = 0.19–0.27 at z/dout2 = 2 beyond the outlet nozzle. Strong cross-sectional motions are observed in planar arrangements, leading to the development of additional regions of negative axial velocity between the outlet nozzles. The boundaries of these regions have nearly zero axial velocity values and can provide reliable ignition and flame stabilization in the case of reactive bidirectional jets. Therefore, the flow structure in planar arrays forms a large stabilization zone, and the obtained results can be used to develop a new multipoint combustion technique.

Investigations on Hot Air Anti-Icing Characteristics with Internal Jet-Induced Swirling Flow

The tangential jet-induced swirling flow is a highly efficient technology for enhancing heat transfer. This paper explores the application of swirling flow of an airfoil/aero-engine in a hot air anti-icing chamber, aiming to improve the anti-icing performance and achieve a more uniform temperature on the surface. A series of numerical computations adopting the SST k − ω turbulent model was carried out to obtain the internal flow and heat transfer characteristics, as well as the surface temperature distributions, considering water evaporation and solid heat conduction. Three jet arrangements, including impingement jets, offset jets, and swirl jets, were studied and compared, which evidently showed that the swirling effect was helpful to elevate the internal heat transfer. Compared to the impingement jets at the Reynolds number of 40,000, the Nusselt number with the offset jets is increased by 19.5%, while the corresponding Nusselt number of the swirl jets is augmented by 44.3%. The swirling flow significantly elevates the swirl number within the internal chamber, intensifying the vortex strength near the wall and increasing the circumferential velocity, which also results in an augmentation of internal pressure loss. By adopting the swirling internal flow, the temperature distribution on the anti-icing surface is more uniform and is increased by up to about 4.1 K in the leading edge when the internal-to-external temperature difference is 80 K. Simultaneously, the heat absorption of water evaporation and the matches between the internal heat transfer and external icing load are of particular importance to determine the anti-icing performance, and this has been discussed in this paper.

Thermal and dynamic characterization of a multi-jet system with different geometry diffusers

This paper proposed to use the impinging jets mixing process to improve the quality of residential heating and air conditioning. The main objective is to meet the requirements of occupants in terms of thermal comfort and air quality by proposing an optimal solution for the thermal homogenization improvement in the rooms by changing of the diffusers geometry and their arrangement in the ventilation and air-conditioning devices in blowing systems. This study involves both experimental and numerical studies of a three diffusers configurations composed of four peripheral jet with similar geometries and a central jet with a different geometry. All the configurations consist of four equidistant peripheral swirling jets, only the central jet that makes the difference between them. The configuration 1 includes a swirling central jet, on the other hand a circular central jet for the configuration 2 and finally a lobed central jet for configuration 3. The velocity and temperature distributions of the three configurations are investigated experimentally and numerically. Experimentally, the multifunction thermo-anemometer have been used to measure flow temperature and velocity. The dynamic and temperature features are more radially spread and get better homogeneity in configuration 3 and this is due to the energy distribution on the radial plane, which is relatively better than configuration 1 and configuration 2. The second part deals with numerical predictions of the dynamics and thermal fields of the three configurations considered. The study was realized using a RANS-based turbulence model. The numerical results are in reasonable agreement with our experiments for the three configurations. With this study, detailed information on the structure of the resulting flow is very useful to deepen the understanding of the physics of jet interaction and to validate turbulence models. The turbulence simulation is realized by the k-ω-SST model. This model gives a satisfactorily predicts the axial drop in velocity and temperature over the entire study range, demonstrating its ability to handle the interaction between swirling and lobe jets. Our results show that the geometry of the central diffuser is essential. This allows the axial velocity to decrease faster than configurations 1 and 2. This increases lateral diffusion, resulting in better homogenization.

Non-circular pressure swirl nozzles injecting into stagnant air

As far as we are aware, all the previous studies have focused on circular injectors. Here, the effect of non-circular orifice shape on pressure swirl injector was investigated experimentally. For this purpose, three injectors; circular, square and rectangular were manufactured. The nozzles had the same cross-sectional area. Water was used as the working fluid and tests were conducted at room temperature and pressure. The Weber number varied from 484 to 1936. Flow parameters of the swirl jets were obtained by an in-house image processing code. The measured parameters were: discharge coefficient, spray angle, breakup length, lateral spread, SMD of drops and wavelength of surface waves formed on the cone. The influence of nozzle shape on all these parameters are discussed.A new breakup regime morphology for non-circular pressure swirl nozzles was defined. At lower Weber numbers, the air core was trapped inside the liquid sheet and relatively large ligaments were formed and separated from the edges (fiber breakup regime). As the Weber number was increased Rayleigh-Taylor instability produced cell-like structures near the nozzle exit. These cell-like structures eventually broke up at the thickened edges of the cells and formed Christmas tree like structures (Christmas tree regime). We found that all the measured flow parameters can best be correlated as a function of Reynolds number and Weber number based on liquid sheet thickness at nozzle exit. All these correlations were reported. Breakup length and lateral spread were heavily influenced by the breakup regime. In fiber breakup regime the breakup length and lateral spread increased with increasing Weber number. However, in Christmas tree (cellular) breakup regime, breakup length and lateral spread decreased with increasing Weber number.

A numerical and experimental investigation into the mixing mechanism of hydrogen transverse jets into an air swirl flow

As a clean fuel with the advantages of abundant reserves, high calorific value, renewability, and zero carbon emissions, hydrogen has broad application prospects in the fields of energy and power. Moreover, the mixing characteristics of hydrogen and air play a crucial role in determining combustion performance. A novel mixing method of hydrogen transverse jets into an air swirl flow was investigated via numerical and experimental approaches. The Schlieren technique and high-speed photography were employed in the experiments. The effects of various swirl numbers and jet momentum flux ratios on the flow field structure, its transient characteristics, and mixing properties were studied. The research results indicate that the complex vortex structure in the mean flow field is jointly affected by the swirl number and the jet momentum flux ratio. An increase in the jet momentum flux ratio has distinct effects on the flow unsteadiness for different swirl numbers, and there exists a critical value of the jet momentum flux ratio that substantially affects the degree of mixing and a characteristic length suitable for normalization of the axial coordinates when describing the centerline concentration decay. This study provides a reference and basis for further research on combustion in air swirl flows of hydrogen transverse jets.

Insights into the hydrodynamics in the annular pipe of industrial‐scale top‐blown smelting furnace

AbstractThe coaxial jet consisting of swirl jet and axial jet plays a critical role in the industrial processes but is rarely investigated; therefore, it is numerically explored by means of the computational fluid dynamics (CFD) approach in the present work. The force on the swirler, axial and tangential velocity at the annular pipe outlet, and the spatial distribution of swirl number (SN) are selected to evaluate the effect of geometrical parameters on the swirling performance. The results clarify that the velocity and their azimuthal components in the transverse cross‐section can be categorized into six segments based on high/low velocity values. The coaxial jets form a weak swirl with high axial, certain tangential, and low radial velocities. x‐ and y‐vorticity vary within −200 to 200 s−1. Coaxial jet mixing decays the SN. Based on the multi‐objective matrix analysis, swirler height has the largest effect on swirl performance followed by diameter, angle, and number based on analysis. Optimal parameters are 130° vane angle, 240 mm diameter, 10 vanes, and 250 mm height of the swirler.

A NUMERICAL STUDY ON COMBUSTION IN ARRAYS OF BIDIRECTIONAL SWIRLING JETS

A numerical study of combustion in bidirectional swirling jets arrays is performed for the first time. A choice of bidirectional flow for designing burner arrays is caused by their advanced properties in terms of combustion stability, long fuel residence time, pollutants emission, etc. The simplest array studied in the paper is of square shape (3 &amp;times; 3) and consists of the central toroidal bidirectional chamber and 8 peripheral cylindrical chambers. Such a decision is made to improve the stability of combustion due to the advantages of the toroidal shape known from the previous studies. The main result for the square array is that the flame surface area increases significantly, and the fuel burning rate is 1.68 times more compared to a single bidirectional chamber. Additionally, the simulations show that the key factor in array combustion stability is related to the formation of central recirculation zones in each bidirectional jet. Based on these results, the multipoint gas turbine combustor is designed. Its primary combustion zone is formed using the multiplied 3 &amp;times; 3 array of bidirectional jets over the annulus. Thus, the overall number of simple vortex chambers in the annular array is 90. A numerical simulation of the new multipoint combustor operation shows a very intense jets interaction in its first half and its efficiency is more than 99&amp;#37;. Moreover, the calculated emission properties at an overall pressure ratio OPR &amp;#61; 40 suit the modern environmental requirements: CO &amp;#61; 12 ppm, NO &amp;#61; 22 ppm.

Annular swirling jet reactor for converting hydrocarbons to olefins and aromatics

This paper describes a novel reactor for high temperature thermochemical conversion of ethane to olefins. The central feature is an efficient flow pattern with a large recirculation zone that provides stable and compact 2500 °C flame and a thin conical annular swirling jet that provides fast transfer of mass, momentum, and heat. The jet is directed through a unique converging–diverging nozzle that maintains relatively low wall temperature and consequently reduces the need for external cooling. The hydrocarbons stream is introduced tangentially through volutes in such a way that there is initially heat transfer with minimal mass transfer followed by fast mixing of countercurrent streams. CFD simulations with detailed kinetics were employed to design and optimize this reactor including the order of the volutes to feed ethane, H2 fuel, oxidizer (O2 and N2 mix), and a cooling N2 gas; oxygen enrichment of the air, and also the overall operating conditions of this flexible and robust reactor. This highly intensified reactor was fabricated and tested at a semi-pilot scale with up to 15 kg/hr feed. The optimized reactor has high selectivity to ethylene and acetylene comparable to conventional steam cracker.

Swirling instability of coaxial liquid jet in gas surroundings

Linear instability analysis of an inviscid coaxial swirling jet is carried out by deriving an analytical dispersion relation of perturbation growth. The azimuthal Rankine vortex and the axial discontinuous velocity distribution are utilized as the jet basic flow. Due to the existence of double interfaces, the instability mechanisms of the coaxial swirling jet are much more complex than those of the single-layered swirling jet. The effects of control parameters (including the swirling ratio, the Weber number, the jet radius ratio, the velocity ratios between different fluids, and the azimuthal velocity jump at the inner interface) on the temporal instability of coaxial swirling jet with different azimuthal modes are studied. By comparing the growth rate of different azimuthal modes, the predominant mode that determines the jet breakup is identified. The results indicate that an increase in the swirling ratio, the Weber number, and the radius ratio can lead to predominant mode transition to larger azimuthal wavenumbers. The velocity ratio between the inner jet and the annular jet and that between the surrounding fluid and the annular jet mainly affect the axial Kelvin–Helmholtz (KH) instability. An enhancement of the KH instability leads to the jet breakup with smaller azimuthal wavenumbers. The azimuthal velocity jump affects the azimuthal KH instability, the centrifugal instability, and the Coriolis instability simultaneously, thus leading to a multiple influence on modes transition. The phase-diagram of the predominant modes is further given, showing that the relative importance between the centrifugal force and the interfacial tension plays a significant role on the transition of predominant modes.

Flow and heat transfer characteristics of an impinging jet augmented with swirl

Jet impingement cooling techniques using conventional nozzles, round jets, and swirling jets are effective heat transfer methods extensively used for various industrial applications. This work proposes a geometrical mechanism that generates augmented swirling and round jets for enhanced heat transfer. The proposed geometry has an axial inlet port and three tangential inlet ports. The total flow is partitioned through these inlet ports using different split ratios (SR), resulting in a single augmented flow comprising swirling and round jets. The impingement heat transfer from a heated flat plate is modelled using steady 3-D RANS based numerical simulations. Also, computations for conventional round jets and swirling jets generated by an in-house developed vane-swirler are performed for the Reynolds number range of 6000–15,000, and for a range of jet-plate distance H = 1.5–4 times the jet diameter D. The optimum conditions for maximum heat transfer for various configurations of jets are presented. From this numerical study, the proposed augmented jet is found to enhance the impingement heat transfer rate at an optimal condition of split ratio (SR-4) and dimensionless jet-plate distance (H/D = 1.5) compared to conventional round jets as well as swirl jets generated by vane swirlers.

Flow field investigation of Confined Coaxial Swirling Jets by Stereo-PIV

This work analyses the isothermal flow field of a research burner exploiting both swirl and radially staged combustion air. The burner is composed of two coaxial co-rotating swirling jets, and the swirl level of the two jets can be controlled independently of each other. The influence of the swirl levels on the flow field is experimentally investigated under isothermal conditions using the Stereo-PIV technique, and the results evidence significant differences in the mean flow field at the different swirl levels. The vortex breakdown occurs in all the investigated cases, except for the combination of the lowest outer swirl level and the intermediate inner swirl level. Besides, the central recirculating flow region shape and size are affected by the momentum ratio and swirl level of the central jet. When the swirl intensities of the two coaxial jets are at their maximum, LDV measurements evidence on the burner axis tangential velocity fluctuations at a frequency of about 86 Hz; a POD-based phase average of the PIV maps allows recognizing the presence of a Precessing Vortex Core (PVC) which induces a periodic merging of the two jets. Those results can be of significance in the design of double swirl burners and for the control of the combustion process. Nevertheless, further tests are required to extend the current analysis to combustion conditions.

Analysis of transport phenomena on cooling a flat surface using swirl jet impingement with crossflow

Enhancing airside convective heat transfer is a challenging problem due to the poor thermal properties of air and the high thermal resistance of the thermal boundary layer. This study presents an innovative method to improve the convective heat transfer of cross airflow over a flat plate using a Swirl jet to suppress the boundary layer thus reducing the thermal resistance. A three-dimensional numerical analysis was performed to study the transport phenomena that occur when a swirl air jet is issued perpendicular to a crossflow of air flowing over a hot flat plate. The finite element method with SST k-ω turbulence model was employed for this numerical study after validation with experimental data from the literature. A parametric study was performed by varying Reynolds number of the jet, Rej(2500−10000), dimensionless jet to plate spacings, Z/D(1−2), swirl number, SW(0.3−0.9), and blockage ratios, BR(0.4−0.6). The thermal performance was assessed by the average heat transfer coefficient, h‾j, in addition to the ratio of heat transfer coefficient between the proposed setup involving crossflow with jet to the reference case of crossflow without jet, h‾j/h‾woj, thus, a correlation is obtained for the average heat transfer coefficient. The friction factor, f, and the pumping power were used to evaluate hydraulic performance. The performance evaluation coefficient, PEC, was chosen to identify the best possible thermal and hydraulic performance. Results show that for all the cases under study, there is a clear enhancement of the heat transfer coefficient when employing a combination of swirl jet with crossflow over a flat plate compared to the case of crossflow without jet. The maximum value of PEC was 1.8 occurring at Reynolds number, Rej, of 10000, swirl number of 0.9, blockage ratio of 0.6, and jet-to-plate spacing of 2D.

Experimental study of the topological flow transformations in an aerial vortex bioreactor with a floating washer.

Research into the flow structure in an aerial vortex bioreactor is relevant for developing the methods for growing cell cultures. Determining the optimal cultivation condition for a certain process is especially important in the case when such parameters of the medium as density and viscosity significantly change with the culture growth in the bioreactor. The research of the flow dynamic was carried out in an 8.5 L universal aerial vortex bioreactor, with a washer freely floating on its surface and stabilizing the motion of the working fluid. The regularities of the vortex motion of the culture medium have been determined by Particle Image Velocimetry depending on its volume and the intensity of rotation of the activator, generating vortex motion in the air. The observed vortex structure and its dynamics at increasing flow swirl intensity are established to coincide with the structure of a confined vortex flow in a cylindrical container with no washer for both single and two-fluid configurations. This novel methodology of the flow optimization shows that an ascending swirling jet forms in the vicinity of the bioreactor axis, and a bubble-like vortex breakdown forms in the axial region. This article is protected by copyright. All rights reserved.