TY - JOUR
T1 - TR-PIV measurements of turbulent confined impinging twin-jets in crossflow
AU - Pastrana, Héctor
AU - Treviño, C.
AU - Pérez-Flores, F.
AU - Martínez-Suástegui, L.
N1 - Publisher Copyright:
© 2022 Elsevier Inc.
PY - 2022/8/1
Y1 - 2022/8/1
N2 - In this work, time-resolved particle image velocimetry (TR-PIV) measurements have been carried out to study the flow structure and flow dynamics of submerged transverse impinging twin-jet flows discharged into a confined laminar crossflow. A parametric study has been carried out for fixed spacing ratio between the jets of s=L/D=3, fixed jet-to-target spacing ratio of H/D=6.73, fixed crossflow Reynolds number of Re=3500, and two jet Reynolds numbers based on the outlet velocities and jet diameter D of Rej=8670 and 9933 that correspond to jet-to-cross-flow velocity ratios of r=vj/u0=10 and 11.46, respectively. Flow measurements in several different planes of the test section are acquired to assess the confinement effect of the bounded jets. Flow visualization images of the mean velocity, vorticity, strain rate distributions, turbulence kinetic energy, and Reynolds stresses have been obtained. The results reveal the dependence of Rej on the trajectory, penetration, crossflow entrainment and lateral spreading of the twin jets. Spectral analysis of the fluctuating velocity components shows the characteristic frequencies related to vortex pairing and vortex breakup, and the shedding frequencies of the upstream and downstream wall jets have also been obtained. The swirling strength criteria has been applied to identify coherent structures, and their development confirms that these structures undergo two or three stages of vortex pairing prior to the vortex breakdown activity. The experimental data has been analyzed using proper orthogonal decomposition (POD), and the most energetic modes, the relative and cumulative energy contributions, dominant POD modes, and temporal POD coefficients have been obtained. The results show that the for Rej=8670, the first two POD modes account for 16.50% of the total kinetic energy, and the cumulative energy of the first 20 POD modes is 55.10%. For Rej=9933, the first two POD modes account for 17.98% of the total energy, and the sum of energies of the first 20 POD modes is 57.13%.
AB - In this work, time-resolved particle image velocimetry (TR-PIV) measurements have been carried out to study the flow structure and flow dynamics of submerged transverse impinging twin-jet flows discharged into a confined laminar crossflow. A parametric study has been carried out for fixed spacing ratio between the jets of s=L/D=3, fixed jet-to-target spacing ratio of H/D=6.73, fixed crossflow Reynolds number of Re=3500, and two jet Reynolds numbers based on the outlet velocities and jet diameter D of Rej=8670 and 9933 that correspond to jet-to-cross-flow velocity ratios of r=vj/u0=10 and 11.46, respectively. Flow measurements in several different planes of the test section are acquired to assess the confinement effect of the bounded jets. Flow visualization images of the mean velocity, vorticity, strain rate distributions, turbulence kinetic energy, and Reynolds stresses have been obtained. The results reveal the dependence of Rej on the trajectory, penetration, crossflow entrainment and lateral spreading of the twin jets. Spectral analysis of the fluctuating velocity components shows the characteristic frequencies related to vortex pairing and vortex breakup, and the shedding frequencies of the upstream and downstream wall jets have also been obtained. The swirling strength criteria has been applied to identify coherent structures, and their development confirms that these structures undergo two or three stages of vortex pairing prior to the vortex breakdown activity. The experimental data has been analyzed using proper orthogonal decomposition (POD), and the most energetic modes, the relative and cumulative energy contributions, dominant POD modes, and temporal POD coefficients have been obtained. The results show that the for Rej=8670, the first two POD modes account for 16.50% of the total kinetic energy, and the cumulative energy of the first 20 POD modes is 55.10%. For Rej=9933, the first two POD modes account for 17.98% of the total energy, and the sum of energies of the first 20 POD modes is 57.13%.
KW - Bounded jets
KW - Coherent structures
KW - Confined impinging twin jets
KW - Jets in crossflow
KW - Particle image velocimetry
KW - Proper orthogonal decomposition (POD)
UR - http://www.scopus.com/inward/record.url?scp=85129469509&partnerID=8YFLogxK
U2 - 10.1016/j.expthermflusci.2022.110667
DO - 10.1016/j.expthermflusci.2022.110667
M3 - Artículo
AN - SCOPUS:85129469509
SN - 0894-1777
VL - 136
JO - Experimental Thermal and Fluid Science
JF - Experimental Thermal and Fluid Science
M1 - 110667
ER -