Journal articles: 'Swirl tube'

1

Huang, Wei Jun, and Qin Zhang. "Swirl-Based Non-Contact Method of Cell Orientation Control." Key Engineering Materials 609-610 (April 2014): 660–65. http://dx.doi.org/10.4028/www.scientific.net/kem.609-610.660.

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Orientation adjustment is an important issue in the micromanipulation of cells. A non-contact method based on a swirl for cell orientation control was introduced in this paper. The swirl is produced by a pair of opposite micro-fluids squirting from two parallel tubes. Cell orientation adjustment is realized by cells rotation due to swirl viscous drag, which drives cells to desired configurations. The appropriate distances between the end face of the two tubes and the distance between the axes of them are 1-3 times tube diameter for the cells rotating in the swirl central zone. Especially when the distances are kept double the cell diameter, cells rotate steadily round the swirl central point. By pulsating jetting, fluctuant micro-fluid are generated which make cell rotating a certain angle. Adjusting the pulse duration, pressure and jetting velocity, the cell rotation angle can be controlled which make orientation control more precisely. The method is valid for cells of different shapes and sizes. The effectiveness of the proposed non-contact method for cell configuration control was verified by experiments.

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Brundrett, E. "Prediction of Airflow With Swirl in Perforated Polyethylene Tubes." Journal of Fluids Engineering 112, no. 4 (December 1, 1990): 447–54. http://dx.doi.org/10.1115/1.2909424.

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The influence upon flow of fan induced inlet swirl is examined for two commonly used sizes of uniformly perforated polyethylene ventilation tubes (polytubes). Swirl is present at the inlet of most polytubes that are directly connected to a supply fan whether or not an antiswirl device is used. Four experimentally obtained inlet swirl angles are examined using swirl modified pressure recovery coefficients, pipe friction factors, and orifice discharge equations. A computational procedure divides the polytube into five equal length segments to obtain a rapid yet acceptably accurate procedure. An iterative microcomputer spreadsheet solves the resulting set of simultaneous equations, providing pressure and flow discharge profiles along the tube that are in very good agreement with the experimental data and with the data of others. An extension of the analysis for uniformly spaced orifices indicates that supply swirl angles greater than 25 deg and large length to diameter ratios should be avoided.

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Sparrow, E. M., N. T. Littlejohn, J. M. Gorman, and J. P. Abraham. "Mass Transfer and Particle Separation by Swirl-Chamber and Swirl-Tube Devices." Numerical Heat Transfer, Part A: Applications 64, no. 8 (October 15, 2013): 611–20. http://dx.doi.org/10.1080/10407782.2013.790276.

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Shi, Hongbo, and Petr Nikrityuk. "The Influence of Inflow Swirl on Cavitating and Mixing Processes in a Venturi Tube." Fluids 5, no. 4 (September 30, 2020): 170. http://dx.doi.org/10.3390/fluids5040170.

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A study of the mixing flows (Schmidt number = 103) in a cavitating Venturi tube that feature linear and swirling flows is presented in this paper. The Large Eddy Simulation (LES) turbulence model, the Schnerr–Sauer cavitation model, and the mixture multiphase model, as implemented in the commercial CFD ANSYS FLUENT 16.2, were employed. The main emphasis is spending on the influence of different inlet swirling ratios on the generation of cavitation and mixing behaviors in a Venturi tube. Four different inflow regimes were investigated for the Reynolds number Re = 19,044, 19,250, 19,622, 21,276: zero swirl, 15% swirl, 25% swirl and 50% swirl velocity relative to the transverse inflow velocity, respectively. The computed velocity and pressure profiles were shown in good agreement with the experiment data from the literature. The predicted results indicate that the imposed swirl flow moves the cavitation bubbles away from throat surfaces toward the throat axis. The rapid mixing between two volumetric components is promoted in the divergent section when the intense swirl is introduced. Additionally, the increase in the swirl ratio from 0.15 to 0.5 leads to a linear increase in the static pressure drop and a nonlinear increase in the vapor production. The reduction in the fluid viscosity ratio from μ2μ1=10 to μ2μ1=1 generates a high cavitation intensity in the throat of the Venturi tube. However, the changes in the pressure drop and vapor volume fraction are significantly small of pure water flow.

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Peng, Weiming, Alex C. Hoffmann, and Huub Dries. "Separation characteristics of swirl-tube dust separators." AIChE Journal 50, no. 1 (January 2004): 87–96. http://dx.doi.org/10.1002/aic.10008.

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6

Ismail, Nurhasanah, Wirachman Wisnoe, and Muhammad Fairuz Remeli. "Experimental Investigation of Orifice Diameter, Swirl Generator and Conical Valve Shape to the Cooling Performance of Ranque-Hilsch Vortex Tube." Applied Mechanics and Materials 510 (February 2014): 174–78. http://dx.doi.org/10.4028/www.scientific.net/amm.510.174.

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This paper is about experimental investigation of the orifice diameter, swirl generator and conical valve shape influence the cooling performance of Ranque-Hilsch vortex tube. From the experiment, its shows that conical valve shape has smallest effect on cooling performance (0.124) of the Ranque-Hilsch vortex tube. It also revealed that swirl generator gave the greatest (0.336) effects to the cooling performance of Ranque-Hilsch vortex tube and have the highest range of difference cooling performance (0.027 to 0.229) compare to conical valve shape (0.073 to 0.087) and orifice diameter (0.009 to 0.012).

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7

Gao, Guang Cai, Jian Jun Wang, and You Hai Jin. "Numerical Study of the Gas Flow in the Swirl Tube." Advanced Materials Research 550-553 (July 2012): 3194–200. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.3194.

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The gas flow field in the swirl tube was studied by experimental measurement and numerical simulation. The results show that the simulation results based on the Reynolds stress turbulent model is in good agreement with the measured results probed by the five orifice Pitot-tube. Meantime, it is analyzed that there is short cut stream at the end of the exit tube, and at the dust discharge jaws, the particles are prone to be re-entrained from the hopper. All results above provide a base for further research on the optimization of the structure and the improvement of the separation performance of the swirl tube.

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8

Kim, Seung-Jun, Yong Cho, and Jin-Hyuk Kim. "Effect of Air Injection on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model." Processes 9, no. 7 (July 7, 2021): 1182. http://dx.doi.org/10.3390/pr9071182.

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Under low flow-rate conditions, a Francis turbine exhibits precession of a vortex rope with pressure fluctuations in the draft tube. These undesirable flow phenomena can lead to deterioration of the turbine performance as manifested by torque and power output fluctuations. In order to suppress the rope with precession and a swirl component in the tube, the use of anti-swirl fins was investigated in a previous study. However, vortex rope generation still occurred near the cone of the tube. In this study, unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted with a scale-adaptive simulation shear stress transport turbulence model. This model was used to observe the effects of the injection in the draft tube on the unsteady internal flow and pressure phenomena considering both active and passive suppression methods. The air injection affected the generation and suppression of the vortex rope and swirl component depending on the flow rate of the air. In addition, an injection level of 0.5%Q led to a reduction in the maximum unsteady pressure characteristics.

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9

Wei, Hang Xin, and Hong Wang. "Structure Design of Swirl Flow Tool in the Natural Gas Well." Applied Mechanics and Materials 741 (March 2015): 563–66. http://dx.doi.org/10.4028/www.scientific.net/amm.741.563.

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In order to solve the problem of gas recovery by liquid drainage, the swirl flow tool was designed. Firstly, the whole structure of the swirl flow tool was introduced. The swirl flow tool includes three units, i.e. the screw basement, restrictor and setting mechanism. The characteristic of the tool is that there does not exist a gap between the outer diameter of the swirl flow tool and the inner diameter of the oil tube. Then, its work principle, setting process and deblocking process were discussed. The application results for the swirl flow tool in the oilfield show that the casing pressure is decreased by 7.0%-17.6% and the average gas production per day is increased by 7.4%-11.9%.

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10

Ewart Brundrett and Peter T. Vermes. "Evaluation of Tube Diameter and Fan Induced Swirl in Polyethylene Ventilation Tubes." Transactions of the ASAE 30, no. 4 (1987): 1131–36. http://dx.doi.org/10.13031/2013.30532.

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11

Dellenback, P. A., D. E. Metzger, and G. P. Neitzel. "Heat Transfer to Turbulent Swirling Flow Through a Sudden Axisymmetric Expansion." Journal of Heat Transfer 109, no. 3 (August 1, 1987): 613–20. http://dx.doi.org/10.1115/1.3248132.

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Experimental data are presented for local heat transfer rates in the tube downstream of an abrupt 2:1 expansion. Water, with a nominal inlet Prandtl number of 6, was used as the working fluid. In the upstream tube, the Reynolds number was varied from 30,000 to 100,000 and the swirl number was varied from zero to 1.2. A uniform wall heat flux boundary condition was employed, which resulted in wall-to-bulk fluid temperatures ranging from 14° C to 50°C. Plots of local Nusselt numbers show a sharply peaked behavior at the point of maximum heat transfer, with increasing swirl greatly exaggerating the peaking. As swirl incressed from zero to its maximum value, the location of peak Nusselt numbers was observed to shift from 8.0 to 1.5 step heights downstream of the expansion. This upstream movement of the maximum Nusselt number was accompanied by an increase in its magnitude from 3 to 9.5 times larger than fully developed tube flow values. For all cases, the location of maximum heat transfer occurred upstream of the flow reattachment point.

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12

Mikhaylenko, C. I. "Dependence of the temperature distribution in the vortex tube on the geometry of the swirler." Proceedings of the Mavlyutov Institute of Mechanics 12, no. 2 (2017): 174–79. http://dx.doi.org/10.21662/uim2017.2.026.

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Modeling of the vortex tube for several variants of the size and shape of inlets of the swirl is carried out. A mathematical model of the process is written. Computational modeling was based on the LES method using the PIMPLE algorithm in the OpenFOAM computational package. Considerable attention was paid to using uniform orthogonalized meshes, while the shape and size of the swirl of the swirl was determined by the feature of the mesh constructed. It is shown that, under certain initial conditions, the effect of thermal stratification can be inversed for some forms of the swirler.

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13

Joo, S. H., K. M. Chun, Y. Shin, and K. C. Lee. "An Investigation of Flame Expansion Speed With a Strong Swirl Motion Using High-Speed Visualization." Journal of Engineering for Gas Turbines and Power 125, no. 2 (April 1, 2003): 485–93. http://dx.doi.org/10.1115/1.1564067.

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In this study, a simple linear supposition method is proposed to separate the flame expansion speed and swirl motion of a flame propagating in an engine cylinder. Two series of images of flames propagating in the cylinder with/without swirl motion were taken by a high frame rate digital video camera. A small tube (4 mm ID) was installed inside the intake port to deliver the fuel/air mixture with strong swirl motion into the cylinder. An LDV was employed to measure the swirl motion during the compression stroke. Under the assumption that flame propagates spherically from the each point of the flame front, a diameter of small spherical flames can be calculated from the two consecutive images of the flame without swirl motion in the cylinder. Using the normalized swirl motion of the mixture during the compression stroke and the spherical flame diameters, the flame expansion speed and swirl ratio of combustion propagation in the engine cylinder can be obtained. This simple linear superposition method for separating the flame expansion speed and swirl motion can be utilized to understand the flow characteristics, such as swirl and turbulence, during the combustion process.

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14

Wu, Hui-Ying, Hui-Er Cheng, Ren-Jun Shuai, and Qiang-Tai Zhou. "An Analytical Model for Decaying Swirl Flow and Heat Transfer Inside a Tube." Journal of Heat Transfer 122, no. 1 (June 16, 1999): 204–7. http://dx.doi.org/10.1115/1.521459.

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Decaying swirl flow can enhance the heat transfer inside a tube. For the decaying swirl flow of which maximum tangential velocity is located in the immediate vicinity of the wall, an analytical model based on the fluid theorem about the moment of momentum is proposed for the local maximum tangential velocity, local friction factor, and local Nusselt number in this paper. The analytical solutions compare favorably with the experimental data. Influences of the Reynolds number, wall roughness and initial tangential-to-axial velocity ratio on the decaying characteristics of the friction factor and Nusselt number have been analyzed. The analytical results show that the swirl flow decays more rapidly at the initial segment; for same conditions, the friction factor decays more severely than the Nusselt number; relative to the values of the nonswirl flow, the friction factor increases more intensely than the Nusselt number. [S0022-1481(00)70401-4]

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15

Jiang, M., H. Yuan, S. Fu, and Q. Shi. "Study on the Performance of a Swirl Tube Column." American Journal of Chemical Engineering 8, no. 1 (2020): 27. http://dx.doi.org/10.11648/j.ajche.20200801.15.

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16

Back, L. H., and P. F. Massier. "Heat Transfer From a Very High Temperature Laminar Gas Flow With Swirl to a Cooled Circular Tube and Nozzle." Journal of Heat Transfer 116, no. 1 (February 1, 1994): 35–39. http://dx.doi.org/10.1115/1.2910880.

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An experimental investigation was carried out to appraise the effect of swirl on heat transfer in the laminar boundary layer development region in a highly cooled tube and nozzle. The ratio of gas-side wall-temperature-to-stagnation-temperature ranged from 0.095 to 0.135. In the swirling flow of argon with ratio of peak-tangential-velocity-to-axial velocity of 3.6 at the injection port, the level of heat transfer to the tube wall was increased from 200 to 60 percent above the level without swirl. In the swirling flows, the wall heat flux level was significantly higher in the tube than in the nozzle downstream. Because of the relatively high heat transfer to the wall, there were appreciable reductions in stagnation enthalpy in the flows that spanned a range of Reynolds numbers from about 360 to 500.

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17

Agrawal, K. N., H. K. Varma, and S. Lal. "Heat Transfer During Forced Convection Boiling of R-12 Under Swirl Flow." Journal of Heat Transfer 108, no. 3 (August 1, 1986): 567–73. http://dx.doi.org/10.1115/1.3246972.

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This work is an experimental investigation of heat transfer augmentation in a horizontal R-12 evaporator, continuing an earlier study [1] by the authors on swirl flow pressure drops. Twisted tapes were used to create swirl motion during the flow boiling inside an evaporator tube of 10 mm i.d. Average heat transfer coefficients have been determined for 60 runs corresponding to three heat fluxes, five mass velocities, and four twist ratios. Swirl flow heat transfer coefficients have been found, in general, to be greater than the corresponding plain flow values, but the degree of enhancement varies depending on the test conditions and the twist ratio of the inserted tape. An empirical correlation which predicts the average swirl flow heat transfer coefficients within ± 30 percent of the experimentally observed values has been successfully developed.

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18

Song, Yu Chao, Hong Tao Gao, and Wang Liu. "The Inner Flow and Heat Transfer Analysis of Round Tube with Different Rotating Speed." Applied Mechanics and Materials 863 (February 2017): 170–74. http://dx.doi.org/10.4028/www.scientific.net/amm.863.170.

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Aiming at the inner flowing characteristics of round tube, the different transient cases of tube with rotating wall boundary are analyzed by CFD, and the six cases are determined according to the different rotating speed respectively. The fluid is water, with the same dimension of tubes, the negative pressure region moves forward in the tube as the increase of rotating speed, and the outflow velocity is high to 31.42 mm/s, being 348.22% more than that of steady case. When the rotating speed is 1 rev./s, there is a lowest temperature band between the wall and center high temperature flow. In the transient temperature analysis, the high temperature cloud changes to cone-like shape, and there is a swirl with lower temperature at the inlet part with a large depth into the tube center. The case with 2 rev./s has the much more uniform temperature distribution than others.

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19

Chong, Cheng Tung, and Simone Hochgreb. "Flow Field of a Model Gas Turbine Swirl Burner." Advanced Materials Research 622-623 (December 2012): 1119–24. http://dx.doi.org/10.4028/www.scientific.net/amr.622-623.1119.

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The flow field of a lab-scale model gas turbine swirl burner was characterised using particle imaging velocimetry (PIV) at atmospheric condition. The swirl burner consists of an axial swirler, a twin-fluid atomizer and a quartz tube as combustor wall. The main non-reacting swirling air flow without spray was compared to swirl flow with spray under unconfined and enclosed conditions. The introduction of liquid fuel spray changes the flow field of the main swirling air flow at the burner outlet where the radial velocity components are enhanced. Under reacting conditions, the enclosure generates a corner recirculation zone that intensifies the strength of the radial velocity. Comparison of the flow fields with a spray flame using diesel and palm biodiesel shows very similar flow fields. The flow field data can be used as validation target for swirl flame modelling.

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20

Wong, Chong Yau, Mohamed Nabil Noui-Mehidi, and Jie Wu. "Performance of swirl tube oil-water separator for downhole applications." APPEA Journal 49, no. 1 (2009): 425. http://dx.doi.org/10.1071/aj08026.

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An experimental comparison is made between a 2 inch (50.8 mm internal diameter) liquid-liquid cylindrical cyclone (LLCC©) and a 2 inch CSIRO-patented liquid-liquid separator (CS-T). Flow visualisation by long-time exposure photography of the LLCC revealed a steady vortex core with a fixed orientation that is independent of the inlet watercut percentage. Visualisation of the CS-T revealed an inverted cone that varied with length at decreasing watercut at the inlet stream. Volume fraction studies showed that the CS-T separation characteristic is similar to the LLCC at the 50% split ratio, but this characteristic departs markedly at higher split ratios. For a watercut of 94%, the optimum split ratio for the present LLCC and CS-T are 55% and 58% respectively.

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Zangana, Lizan, and Ramzi Barwari. "Experimental study and CFD analysis of energy separation in a counter flow vortex tube." Thermal Science, no. 00 (2019): 418. http://dx.doi.org/10.2298/tsci190510418z.

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In this manuscript, both experimental and numerical investigations have been carried out to study the mechanism of separation energy and flow phenomena in the counter flow vortex tube. This manuscript presents a complete comparison between the experimental investigation and CFD analysis. The experimental model was manufactured with (total length of 104 mm and the inner diameter of 8 mm, and made of cast iron) tested under different inlet pressures (4, 5 and 6 bar). The thermal performance has been studied for hot and cold outlet temperature as a function of mass fraction ? (0.3- 0.8). Three-dimensional numerical modeling using the k-? model used with code (Fluent 6.3.26). Two types of velocity components are studied (axial and swirl). The results show any increase in both cold mass fraction and inlet pressure caused to increase ?Tc, and the maximum ?Tc value occurs at P = 6 bar. The coefficient of performance (COP) of two important factors in the vortex tube which are a heat pump and a refrigerator have been evaluated, which ranged from 0.25 to 0.74. A different axial location (Z/L = 0.2, 0.5, and 0.8) was modeled to evaluate swirl velocity and radial profiles, where the swirl velocity has the highest value. The maximum axial velocity is 93, where it occurs at the tube axis close to the inlet exit (Z/L=0.2). The results showed a good agreement for experimental and numerical analysis.

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22

Srinivasan, Vijayaragham, Kambiz Vafai, and Richard N. Christensen. "Analysis of Heat Transfer and Fluid Flow Through a Spirally Fluted Tube Using a Porous Substrate Approach." Journal of Heat Transfer 116, no. 3 (August 1, 1994): 543–51. http://dx.doi.org/10.1115/1.2910905.

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An innovative approach was opted for modeling the flow and heat transfer through spirally fluted tubes. The model divided the flow domain into two regions. The flutes were modeled as a porous substrate with direction-dependent permeabilities. This enabled modeling the swirl component in the fluted tube. The properties of the porous substrate such as its thickness, porosity, and ratio of the direction-dependent permeabilities were obtained from the geometry of the fluted tube. Experimental data on laminar Nusselt numbers and friction factors for different types of fluted tubes representing a broad range of flute geometry were available. Experimental data from a few of the tubes tested were used to propose a relationship between the permeability of the porous substrate and the flute parameters, particularly the flute spacing. The governing equations were discretized using the Finite Element Method. The model was verified and applied to the other tubes in the test matrix. Very good agreement was found between the numerical predictions and the experimental data.

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Gilham, S., P. C. Ivey, and J. M. Owen. "Self-Induced Flow in a Stepped Rotating Tube." Journal of Engineering for Gas Turbines and Power 114, no. 2 (April 1, 1992): 268–74. http://dx.doi.org/10.1115/1.2906583.

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Self-induced flow occurs when a tube, open at one end and sealed at the other, is rotated about its central axis: Fluid flows along the axis from the open end toward the sealed end and returns in a layer adjacent to the inner surface of the tube. This mechanism, which can occur under isothermal or nonisothermal conditions, is believed to be responsible for the so-called “hot-poker effect” that was observed during anti-icing tests on the nose bullet of an aeroengine. This paper describes a combined theoretical and experimental study of self-induced flow. It is shown that, for the length-to-diameter (L/D) ratios and rotational Reynolds numbers associated with the anti-icing tubes of aeroengines, the laminar flow near the sealed end of the tube is similar to that of the so-called free disk. Swirl in the air outside the open end reduces the self-induced flow, but flow can reach the sealed end of a stepped tube that has either a sudden contraction or a sudden enlargement.

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24

Volov, Vyacheslav, and Anton Lyaskin. "Effect of secondary swirl in supersonic gas and plasma flows in the self-vacuuming vortex tube." MATEC Web of Conferences 209 (2018): 00020. http://dx.doi.org/10.1051/matecconf/201820900020.

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This article presents the results of simulation for a special type of vortex tubes – self-vacuuming vortex tube (SVT), for which extreme values of temperature separation and pressure drop are realized. The main results of this study are the flow structure in the SVT and energy loss estimations on oblique shock waves, gas friction, instant expansion and organization of vortex bundles in SVT.

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Cervantes, Michel J., and L. Håkan Gustavsson. "On the Use of the Squire-Long Equation to Estimate Radial Velocities in Swirling Flows." Journal of Fluids Engineering 129, no. 2 (August 7, 2006): 209–17. http://dx.doi.org/10.1115/1.2409331.

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A method to estimate the radial velocity in swirling flows from experimental values of the axial and tangential velocities is presented. The study is motivated by the experimental difficulties to obtain this component in a draft tube model as evidenced in the Turbine-99 IAHR∕ERCOFTAC Workshop. The method uses a two-dimensional nonviscous description of the flow. Such a flow is described by the Squire-Long equation for the stream function, which depends on the boundary conditions. Experimental values of the axial velocities at the inlet and outlet of the domain are used to obtain the boundary conditions on the bounded domain. The method consists of obtaining the equation related to the domain with an iterative process. The radial velocity profile is then obtained. The method may be applied to flows with a swirl number up to about Sw=0.25. The critical value of the swirl number depends on the velocity profiles and the geometry of the domain. The applicability of the methodology is first performed on a swirling flow in a diffuser with a half angle of 3deg at various swirl numbers, where three-dimensional (3D) laser Doppler velocimeter (LDV) velocity measurements are available. The method is then applied to the Turbine-99 test case, which consists in a model draft tube flow where the radial inlet velocity was undetermined. The swirl number is equal to Sw=0.21. The stability and the convergence of the approach is investigated in this case. The results of the pressure recovery are then compared to the experiments for validation.

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Patel, Vipul, and Rupesh Shah. "Analysis of LPG diffusion flame in tube type burner." Journal of Mechanical Engineering and Sciences 13, no. 3 (September 26, 2019): 5278–93. http://dx.doi.org/10.15282/jmes.13.3.2019.05.0431.

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The present research aims to analyse diffusion flame in a tube type burner with Liquefied petroleum gas (LPG) as a fuel. An experimental investigation is performed to study flame appearance, flame stability, Soot free length fraction (SFLF) and CO emission of LPG diffusion flame. Effects of varying air and fuel velocities are analysed to understand the physical process involved in combustion. SFLF is measured to estimate the reduction of soot. Stability limits of the diffusion flame are characterized by the blowoff velocity. Emission characteristic in terms of CO level is measured at different equivalence ratios. Experimental results show that the air and fuel velocity strongly influences the appearance of LPG diffusion flame. At a constant fuel velocity, blue zone increases and the luminous zone decreases with the increase in air velocity. It is observed that the SFLF increases with increasing air velocity at a constant fuel velocity. It is observed that the blowoff velocity of the diffusion flame increases as fuel velocity increases. Comparison of emission for flame with and without swirl indicates that swirl results in low emission of CO and higher flame stability. Swirler with 45° vanes achieved the lowest CO emission of 30 ppm at Φ = 1.3.

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Eiamsa-ard, S., and P. Promthaisong. "Counter-rotation vortex flows and heat transfer mechanisms in a V-spirally-corrugated tube." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 233, no. 7 (February 13, 2019): 928–52. http://dx.doi.org/10.1177/0957650919829367.

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The flow and heat transfer behavior of newly designed V-corrugated tubes with various numbers of starts ( N = 2, 3, 4, and 5), depth ratios ( DR = 0.02–0.14), and pitch ratios ( PR = 1.0–2.0) were studied in the turbulent flow region (5000 ≤ Re ≤ 20,000). The friction factor ( f), friction factor ratio ( f/ f0), Nusselt number ( Nu), Nusselt number ratio ( Nu/ Nu0), and thermal enhancement factor ( TEF) values are reported. The computational results indicate that the conventional spirally-corrugated tube create swirl flows while V-corrugated tubes generate a counter-rotating vortex flow that impinges upon the lower zone of the tubes and enhances fluid transfer between tube core and near-wall regions. The results also show that the f, Nu, f/ f0, Nu/ Nu0 monotonically increase with decreasing PR, increasing DR and N, while the TEF is dependent on a tradeoff between f/ f0 and Nu/ Nu0. Over the studied range, the f/ f0, Nu/ Nu0, and TEF were in the ranges of 1.36–43.82, 1.00–5.35, and 0.80–2.11, respectively. The maximum TEF, 2.11, was achieved with a V-corrugated tube with an N of 4, DR of 0.06, and PR of 2.0 at Re = 5000.

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Zhou, Xing, He-gao Wu, and Chang-zheng Shi. "Numerical and experimental investigation of the effect of baffles on flow instabilities in a Francis turbine draft tube under partial load conditions." Advances in Mechanical Engineering 11, no. 1 (January 2019): 168781401882446. http://dx.doi.org/10.1177/1687814018824468.

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An improved method for preventing vortex rope formation and alleviating the associated pressure fluctuations in turbine draft tubes is investigated using baffles in the draft tube to hinder the swirling flow emerging from a Francis turbine runner. A strong swirl produces flow instabilities and pressure fluctuations. Partial load operating conditions at the rated water head and three flow rates are taken into consideration. It is demonstrated using a computational fluid dynamics simulation that this method effectively eliminates the vortex rope, particularly when using four baffles. The amplitude of the pressure pulsation in the draft tube modified with four baffles was 0.42 times that in a traditional draft tube. The baffles were found to reduce the tangential velocity of the flow in the draft tube and consequently hinder the development of the fierce swirling flow. This type of decrease is more significant compared to the gradual decay due to viscous effects of the solid wall in a traditional draft tube. The conclusion was verified by the results of experiments conducted using a novel device. The measured increase in turbine efficiency exceeded 3% at the evaluated partial loading point, indicating improved economic performance of the turbine.

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ALEKSEENKO, S. V., P. A. KUIBIN, V. L. OKULOV, and S. I. SHTORK. "Helical vortices in swirl flow." Journal of Fluid Mechanics 382 (March 10, 1999): 195–243. http://dx.doi.org/10.1017/s0022112098003772.

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Helical vortices in swirl flow are studied theoretically and experimentally.A theory of helical vortices has been developed. It includes the following results: an analytical solution describing an elementary helical vortex structure – an infinitely thin filament; a solution for axisymmetrical vortices accounting for the helical shape of vortex lines and different laws of vorticity distribution; a formula for calculation of the self-induced velocity of helical vortex rotation (precession) in a cylindrical tube; an explanation of the zone with reverse flow (recirculation zone) arising in swirl flows; and the classification of vortex structures.The experimental study of helical vortices was carried out in a vertical hydrodynamical vortex chamber with a tangential supply of liquid through turning nozzles. Various vortex structures were formed owing to changing boundary conditions on the bottom and at the exit section of the chamber. The hypothesis of helical symmetry is confirmed for various types of swirl flow. The stationary helical vortex structures are described (most of them for the first time) the features of which agree with the results and predictions of the theoretical model developed. They are the following: a rectilinear vortex; a composite columnar vortex; helical vortices screwed on the right or on the left; a vortex with changing helical symmetry; a double helix – two entangled vortex filaments of the same sign.

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30

Saha, S. K., and A. Dutta. "Thermohydraulic Study of Laminar Swirl Flow Through a Circular Tube Fitted With Twisted Tapes." Journal of Heat Transfer 123, no. 3 (January 3, 2001): 417–27. http://dx.doi.org/10.1115/1.1370500.

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Heat transfer and pressure drop characteristics in a circular tube fitted with twisted tapes have been investigated experimentally. Laminar swirl flow of a large Prandtl number 205<Pr<518 viscous fluid was considered. The swirl was generated by short-length twisted-tape inserts; regularly spaced twisted-tape elements with multiple twists in the tape module and connected by thin circular rods; and smoothly varying (gradually decreasing) pitch twisted-tapes. The heat transfer test section was heated electrically imposing axially and circumferentially constant wall heat flux (UHF) boundary condition. Reynolds number, Prandtl number, twist ratio, space ratio, number of tuns in the tape module, length of the twisted-tape and smoothness of the swirling pitch govern the characteristics. Friction factor and Nusselt number are lower for short-length twisted-tape than those for full-length twisted-tape. On the basis of constant pumping power and constant heat duty, however, short-length twisted-tapes are found to perform better than full-length twisted-tapes for tighter twists. Thermohydraulic performance shows that twisted-tapes with multiple twists in the tape module is not much different from that with single twist in the tape module. Friction factor and Nusselt number are approximately 15 percent lower for twisted-tapes with smooth swirl having the average pitch same as that of the uniform pitch (throughout) twisted-tape and the twisted-tapes with gradually decreasing pitch perform worse than their uniform-pitch counterparts.

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31

Kassim, Muna S., Wajeeh Kamal Hasan, Hasanen Mohammed Hussen, and Laith Jaafer Habeeb. "Experimental and Numerical Study in Horizontal Tube by using Swirl Device." Journal of Engineering and Applied Sciences 14, no. 14 (December 20, 2019): 4905–18. http://dx.doi.org/10.36478/jeasci.2019.4905.4918.

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32

Lin, Sui, Jirui Chen, and Georgios H. Vatistas. "A heat transfer relation for swirl flow in a vortex tube." Canadian Journal of Chemical Engineering 68, no. 6 (December 1990): 944–47. http://dx.doi.org/10.1002/cjce.5450680608.

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33

Biegger, Christoph, Corrado Sotgiu, and Bernhard Weigand. "Numerical investigation of flow and heat transfer in a swirl tube." International Journal of Thermal Sciences 96 (October 2015): 319–30. http://dx.doi.org/10.1016/j.ijthermalsci.2014.12.001.

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34

Eiamsa-ard, Smith, Sarawut Rattanawong, and Pongjet Promvonge. "Turbulent convection in round tube equipped with propeller type swirl generators." International Communications in Heat and Mass Transfer 36, no. 4 (April 2009): 357–64. http://dx.doi.org/10.1016/j.icheatmasstransfer.2009.01.007.

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35

Aydin, Orhan, Mete Avci, Burak Markal, and M. Yusuf Yazici. "An experimental study on the decaying swirl flow in a tube." International Communications in Heat and Mass Transfer 55 (July 2014): 22–28. http://dx.doi.org/10.1016/j.icheatmasstransfer.2014.04.012.

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36

Garimella, S., and R. N. Christensen. "Heat Transfer and Pressure Drop Characteristics of Spirally Fluted Annuli: Part II—Heat Transfer." Journal of Heat Transfer 117, no. 1 (February 1, 1995): 61–68. http://dx.doi.org/10.1115/1.2822324.

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This paper is the second of two papers that present the results of a comprehensive study of heat transfer and pressure drop in annuli with spirally fluted inner tubes for the laminar, transition, and turbulent flow regimes. Fourteen fluted tubes with varying geometries were studied, with up to three outer smooth tubes for each fluted tube. Flow patterns and transitions between flow regimes investigated through visualization tests, friction factor data (from Part I), and tube surface-temperature measurements were used to explain the enhancement phenomena. The fluted inner tubes induced a significant degree of swirl in the flow, and transition occurred in the 310 < Re < 1000 range. A Nusselt number correlation was developed in terms of the fluted annulus friction factor developed in Part I and geometric parameters. Nusselt numbers were between 4 and 20 times the smooth annulus values in the low Re range, while turbulent enhancements were between 1.1 and 4.0. These enhancement values can be used in conjunction with friction factor increase values reported in Part I to determine appropriate ranges of applicability for spirally enhanced annuli.

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37

Susan-Resiga, Romeo, Gabriel Dan Ciocan, Ioan Anton, and François Avellan. "Analysis of the Swirling Flow Downstream a Francis Turbine Runner." Journal of Fluids Engineering 128, no. 1 (July 31, 2005): 177–89. http://dx.doi.org/10.1115/1.2137341.

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An experimental and theoretical investigation of the flow at the outlet of a Francis turbine runner is carried out in order to elucidate the causes of a sudden drop in the draft tube pressure recovery coefficient at a discharge near the best efficiency operating point. Laser Doppler anemometry velocity measurements were performed for both axial and circumferential velocity components at the runner outlet. A suitable analytical representation of the swirling flow has been developed taking the discharge coefficient as independent variable. It is found that the investigated mean swirling flow can be accurately represented as a superposition of three distinct vortices. An eigenvalue analysis of the linearized equation for steady, axisymmetric, and inviscid swirling flow reveals that the swirl reaches a critical state precisely (within 1.3%) at the discharge where the sudden variation in draft tube pressure recovery is observed. This is very useful for turbine design and optimization, where a suitable runner geometry should avoid such critical swirl configuration within the normal operating range.

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38

Eiamsa-ard, S., and P. Promvonge. "Numerical investigation of turbulent swirling flows through an abrupt expansion tube." ASEAN Journal on Science and Technology for Development 23, no. 1&2 (October 30, 2017): 55. http://dx.doi.org/10.29037/ajstd.87.

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A numerical investigation of turbulent swirling flows through an abrupt expansion tube is reported. The TEFESS code, based on a staggered Finite Volume approach with the standard k-ε model and first-order numerical schemes built-in, was used to carry out all the computations. The code has been modified in the present work to incorporate the ASM and two second-order numerical schemes. The ASM, which includes the non-gradient convection terms arising from the transformation from Cartesian to cylindrical coordinates, was investigated for isothermal flows by applying it to the flow through an abrupt expansion tube with or without swirl flows. In addition, to investigate the effects of numerical diffusion on the predicted results, two second-order differencing schemes, namely, second-order upwind and the quadratic upstream interpolation, were used to compare with the first-order hybrid scheme. An abrupt expansion tube with non-swirling flow, predicted results using both the k-ε model and the ASM were in good agreement with measurements. For swirling flows, the calculated results suggested that the use of the ASM with a second-order numerical scheme leads to better agreement between the numerical results and experimental data, while the k-ε model is incapable of capturing the stabilizing effect of the swirl.

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39

Changcharoen, W., P. Samruaisin, P. Eiamsa-ard, and S. Eiamsa-ard. "Heat transfer characteristics of decaying swirl flow through a circular tube with co/counter dual twisted-tape swirl generators." Thermophysics and Aeromechanics 23, no. 4 (July 2016): 523–36. http://dx.doi.org/10.1134/s0869864316040053.

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40

Elvery, D. G., and K. Bremhorst. "Wall Pressure and Effective Wall Shear Stresses in Heat Exchanger Tube Inlets With Application to Erosion-Corrosion." Journal of Fluids Engineering 119, no. 4 (December 1, 1997): 948–53. http://dx.doi.org/10.1115/1.2819522.

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Inclined flow into tube inlets is studied in order to identify flow characteristics associated with enhanced erosion-corrosion rates at tube inlets. Measured wall pressures and shear stresses are presented for inlet flow with inclination angles up to 60 deg for a tube Reynolds number of 71,000. These show that the areas with most potential for wear are located near the reattachment point of the recirculation bubble as well as in regions at the downstream side of the tube inlet. The latter are located opposite the recirculation region but away from the symmetry plane due to strong swirl of the flow in that region. The results are related to erosion-corrosion patterns observed in practice.

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41

Yongchao, Rao, Sun Yi, Wang Shuli, and Jia Ru. "Numerical Simulation Study on the Law of Attenuation of Hydrate Particles in a Gas Transmission Pipeline." Energies 12, no. 1 (December 25, 2018): 58. http://dx.doi.org/10.3390/en12010058.

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Based on the swirl flow of gas hydrate pipeline safety flow technology, the numerical simulation method is used to study the attenuation law of hydrate particles, which is of great significance for expanding the boundary of safe flow. The results show that the size of the initial swirl number is mainly related to the twist rate and has nothing to do with the Reynolds number; the smaller the twist rate, the greater the Reynolds number, the greater the number of swirling flow in the same position in the pipeline. The concentration has almost no effect on the change of the swirl number; for the non-dimensional swirl number, and the numerical simulation is roughly the same as the results of the paper, the attenuation coefficient beta and ln (Re) has a linear relationship. The no twist tape is six to eight times larger than the volume fraction of the twisted belt, and the smaller the twist tape twist, the smaller the particle deposition is, the higher the initial concentration of the particles in the pipe, and the larger the volume fraction of the hydrate particles deposited by the tube wall.

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42

Kro¨ner, M., J. Fritz, and T. Sattelmayer. "Flashback Limits for Combustion Induced Vortex Breakdown in a Swirl Burner." Journal of Engineering for Gas Turbines and Power 125, no. 3 (July 1, 2003): 693–700. http://dx.doi.org/10.1115/1.1582498.

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Flame flashback from the combustion chamber into the mixing zone limits the reliability of swirl stabilized lean premixed combustion in gas turbines. In a former study, the combustion induced vortex breakdown (CIVB) has been identified as a prevailing flashback mechanism of swirl burners. The present study has been performed to determine the flashback limits of a swirl burner with cylindrical premixing tube without centerbody at atmospheric conditions. The flashback limits, herein defined as the upstream flame propagation through the entire mixing tube, have been detected by a special optical flame sensor with a high temporal resolution. In order to study the effect of the relevant parameters on the flashback limits, the burning velocity of the fuel has been varied using four different natural gas-hydrogen-mixtures with a volume fraction of up to 60% hydrogen. A simple approach for the calculation of the laminar flame speeds of these mixtures is proposed which is used in the next step to correlate the experimental results. In the study, the preheat temperature of the fuel mixture was varied from 100°C to 450°C in order to investigate influence of the burning velocity as well as the density ratio over the flame front. Moreover, the mass flow rate has been modified in a wide range as an additional parameter of technical importance. It was found that the quenching of the chemical reaction is the governing factor for the flashback limit. A Peclet number model was successfully applied to correlate the flashback limits as a function of the mixing tube diameter, the flow rate and the laminar burning velocity. Using this model, a quench factor can be determined for the burner, which is a criterion for the flashback resistance of the swirler and which allows to calculate the flashback limit for all operating conditions on the basis of a limited number of flashback tests.

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43

Badiger, Shankar, Vadiraj V. Katti, and Anil R. Tumkur. "Heat Transfer Characteristics of a Coaxial Inverse Diffusion Flame Jet Impingement with an Induced Swirl." International Journal of Heat and Technology 38, no. 4 (December 31, 2020): 887–94. http://dx.doi.org/10.18280/ijht.380415.

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Flame jet has a wide range of applications in the industries and also in domestics field. The efforts have been put to enhance the heat transfer and to reduce the emissions from the premixed and inverse diffusion flame burners. Especially, the IDF burner suffers from lack of proper air and fuel mixing, the swirl generated motion from twisted tape would improve the combustion efficiency. Therefore, an aim of experiment is to study the heat transfer characteristics of an inverse diffusion flame (IDF) jet impinging on a flat surface in a coaxial tube burner with swirl. The twisted tape of 15mm pitch creates the swirl in the flame jet (Corresponding to the twist ratio of 3 and swirl number of 0.52). An effect of swirl at air jet Reynolds number of 1000 to 2500 and surface of the burner-to-impingement plate distance (H/da) varying from 2 to 20 is studied at fixed equivalence ratio (ϕ) of 1.1. An average heat flux and peak heat flux are studied for the region of 0<r/da<3 on an impingement plate. From an investigation, it is found that the swirling in the flame jet enhances the average heat flux by up to 179.2%. The maximum average heat flux is found at the optimal burner-to-target plate distance of 8.

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44

Carrotte, J. F., D. W. Bailey, and C. W. Frodsham. "Detailed Measurements on a Modern Combustor Dump Diffuser System." Journal of Engineering for Gas Turbines and Power 117, no. 4 (October 1, 1995): 678–85. http://dx.doi.org/10.1115/1.2815453.

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An experimental investigation has been carried out to determine the flow characteristics and aerodynamic performance of a modern gas turbine combustor dump diffuser. The system comprised a straight walled prediffuser, of area ratio 1.35, which projected into a dump cavity where the flow divided to pass either into the flame tube or surrounding feed annuli. In addition, a limited amount of air was removed to simulate flow used for turbine cooling. The flame tube was relatively deep, having a radial depth 5.5 times that of the passage height at prediffuser inlet, and incorporated burner feed arms, cowl head porosity, cooling rings, and primary ports. Representative inlet conditions to the diffuser system were generated by a single-stage axial flow compressor. Results are presented for the datum configuration, and for a further three geometries in which the distance between prediffuser exit and the head of the flame tube (i.e., dump gap) was reduced. Relatively high values of stagnation pressure loss were indicated, with further significant increases occurring at smaller dump gaps. These high losses, which suggest a correlation with other published data, are due to the relatively deep flame tube and short diffuser length. Furthermore, the results also focus attention on how the presence of a small degree of diffuser inlet swirl, typical of that which may be found within a gas turbine engine, can result in large swirl angles being generated farther downstream around the flame tube. This is particularly true for flow passing to the inner annulus.

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45

Zhang, Dong Hui, and Jiao Gao. "Numerical Study of Circular Tube inserted Arc Belt on Fluid Flow and Heat Transfer under Laminar Flow." Key Engineering Materials 561 (July 2013): 460–65. http://dx.doi.org/10.4028/www.scientific.net/kem.561.460.

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The objective of this paper is to study the characteristic of a circular tube with a built-in arc belt on fluid flow and heat transfer in uniform wall temperature flows. Numerical simulations for hydrodynamically laminar flow was direct ran at Re between 600 and 1800. Preliminary results on velocity and temperature statistics for uniform wall temperature show that, arc belt can swirl the pipe fluid, so that the fluid at the center of the tube and the fluid of the boundary layer of the wall can mix fully, and plays the role of enhanced heat transfer, but also significantly increases the resistance of the fluid and makes the resistance coefficient of the enhanced tube greater than smooth tube. The combination property PEC is all above 1.5.

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46

Durbin, M. D., M. D. Vangsness, D. R. Ballal, and V. R. Katta. "Study of Flame Stability in a Step Swirl Combustor." Journal of Engineering for Gas Turbines and Power 118, no. 2 (April 1, 1996): 308–15. http://dx.doi.org/10.1115/1.2816592.

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A prime requirement in the design of a modern gas turbine combustor is good combustion stability, especially near lean blowout (LBO), to ensure an adequate stability margin. For an aeroengine, combustor blow-off limits are encountered during low engine speeds at high altitudes over a range of flight Mach numbers. For an industrial combustor, requirements of ultralow NOx emissions coupled with high combustion efficiency demand operation at or close to LBO. In this investigation, a step swirl combustor (SSC) was designed to reproduce the swirling flow pattern present in the vicinity of the fuel injector located in the primary zone of a gas turbine combustor. Different flame shapes, structure, and location were observed and detailed experimental measurements and numerical computations were performed. It was found that certain combinations of outer and inner swirling air flows produce multiple attached flames, aflame with a single attached structure just above the fuel injection tube, and finally for higher inner swirl velocity, the flame lifts from the fuel tube and is stabilized by the inner recirculation zone. The observed difference in LBO between co- and counterswirl configurations is primarily a function of how the flame stabilizes, i.e., attached versus lifted. A turbulent combustion model correctly predicts the attached flame location(s), development of inner recirculation zone, a dimple-shaped flame structure, the flame lift-off height, and radial profiles of mean temperature, axial velocity, and tangential velocity at different axial locations. Finally, the significance and applications of anchored and lifted flames to combustor stability and LBO in practical gas turbine combustors are discussed.

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47

Kadyirov, A. I., J. V. Karaeva, and S. I. Islamova. "INVESTIGATION OF SWIRL INTENSITY IN CIRCULAR TUBE INDUCED BY SHORT TWISTED TAPES." Transactions of Academenergo 54, no. 1 (March 2019): 16–27. http://dx.doi.org/10.34129/2070-4755-2019-54-1-16-27.

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48

Owaki, Takashi, and Akira Umemura. "Premixed swirl combustion modes emerging for a burner tube with converging entrance." Proceedings of the Combustion Institute 31, no. 1 (January 2007): 1067–74. http://dx.doi.org/10.1016/j.proci.2006.08.072.

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49

Park, Yusun, and Soon Heung Chang. "Swirl flow analysis in a helical wire inserted tube using CFD code." Nuclear Engineering and Design 240, no. 10 (October 2010): 3405–12. http://dx.doi.org/10.1016/j.nucengdes.2010.07.015.

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50

Gül, H. "Enhancement of Heat Transfer in a Circular Tube With Tangential Swirl Generators." Experimental Heat Transfer 19, no. 2 (April 2006): 81–93. http://dx.doi.org/10.1080/08916150500318422.

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Journal articles on the topic 'Swirl tube'

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