Analysis of local entrainment rate in the initial region of isothermal free swirling jets by Stereo PIV

Cozzi, Franco; Coghe, A.; Sharma, Rohit

doi:10.1016/j.expthermflusci.2018.01.013

Cited by 22 publications

(8 citation statements)

References 53 publications

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“…† Lets explain the strange unit [J m 2 /kg] used in this paper: E = ½ρ ʃv 2 dV, where dV = dx•dy•dz and only v, dx and dy are measured, ρ ≈ 1.2kg/m 3 is the density of air and dz ≈ 1 mm is the thickness of the laser sheet, but these quantities are not measured, therefore we publish only safe numbers: E = Ereal / ρ / dz. (2) where the subscript S denotes spatial averaging and v' is the already Reynolds-decomposed velocity field. We can see that for larger velocities, the curve lacks inflexion point --it is convex since the origin saying that parabolic region is smaller than one IA.…”

Section: Methodsmentioning

confidence: 99%

“…In mixing studies, the jet can be swirled by using a fixed propeller in the nozzle, which widens the jet profile and speeds up the turbulence evolution [1]. This is in the literature refereed as a swirling jet [2]. If one would like to avoid net angular momentum in the downstream [3], then the counterswirler consists of a inner-ring and a oppositely oriented outer-ring of blades resulting into a pair of concentric jets rotating oppositely.…”

Section: Introductionmentioning

confidence: 99%

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The PIV study of air flow past the counter-swirler 53983

Duda

2018

MATEC Web Conf.

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PIV (particle image velocimetry) measurement of the air flow past a counter-swirler 53983 (anticlockwise swirler surrounded by clockwise swirler) is performed. The measurement is focused to an area at the boundary between the inner swirling jet and the outer one rotating oppositely. The Reynolds number Re based on the inner swirler diameter ranged form 1.2·103 to 2.1·104. By using band pass filtering the shear layer and vortices in the contact region between counter-swirling jets is highlighted. The shear layer between these regions shortens and decays into vortices as Reynolds number increases.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The PIV study of air flow past the counter-swirler 53983

Duda

2018

MATEC Web Conf.

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“…The nozzle exit is located 7 𝑚𝑚 above a 250 𝑚𝑚 diameter circular end plate, named flange in Figure 3(a), and the blockage ratio of the annular jet is 𝐵 = 𝐷 𝑝,𝑒𝑥𝑡 2 𝐷 2 ⁄ ≅ 0.44, where 𝐷 𝑝,𝑒𝑥𝑡 = 24 𝑚𝑚 is the external diameter of the central injector. The geometric configuration of the swirl generator for the annular jet is the same as that used in previous works [12][13][14] and more detail can be found in [12].…”

Section: The Confined Double Swirling Burnermentioning

confidence: 99%

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

Cozzi,

Francabandiera,

Zampini

2023

J. Phys.: Conf. Ser.

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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.

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“…However, this method requires a highly physical model and high cost. Point and surface flow field measurements using LDV and particle image velocimetry (PIV) [7] and bulk flow field measurements using V3V have also been proposed. However, these methods have a small measurement range, and it is difficult to measure the overall flow-field distribution in a project.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Pumping Station Inlet Characteristics Based on Vorticity

Xi¹,

Lu²,

Wang³

et al. 2022

Int. j. simul. model.

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This study aims to solve this problem and understand the formation mechanism of the vortex attached to the side pump sump. Thus, numerical simulations were conducted using the calculation software, and the flow characteristics of the side pump sump were studied based on the vorticity field. The flow field data of the physical model of the pumping station forebay and pump sump were obtained by particle image velocimetry. The distribution of vorticity in the different flow layers and vertical axes at the study location was obtained using Tecplot postprocessing software and corroborated with the results of the numerical simulations. This basis was used to analyse the mechanism of the formation of the adherent vortex. Results show that the inflow distribution is uneven and the water flow resistance and vortex strength are imbalanced due to the asymmetry of the vorticity of the inflow of the side pump sump. This causes the attachment of the vortex to the wall, which causes the generation of the suction vortex, vibration of the unit, and instability of the overcurrent, endangering the safety of the project.

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Analysis of local entrainment rate in the initial region of isothermal free swirling jets by Stereo PIV

Cited by 22 publications

References 53 publications

The PIV study of air flow past the counter-swirler 53983

The PIV study of air flow past the counter-swirler 53983

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

Analysis of Pumping Station Inlet Characteristics Based on Vorticity

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