Aerospace Knowledge and Technology Journal

Aerospace Knowledge and Technology Journal

Numerical Modeling of the Unsteady Behavior of a Pulsed Jet in the Near-Nozzle Region

Document Type : Research Paper

Author
Soheila Abdolahi
Assistant Professor, Ministry of Science, Research and Technology, Iran
Abstract
In this study, the unsteady behavior of a pulsed air jet in a quiescent environment was investigated using two-dimensional numerical simulations. First, to verify the accuracy of the numerical model, a steady jet flow was simulated under laboratory-like conditions, and the results were compared with experimental data. The results confirmed that the RNG k–ε turbulence model combined with a compressible solver can accurately reproduce the main characteristics of a free jet flow. Subsequently, a pulsed jet with a frequency of 100 Hz was analyzed. The contours of velocity and vorticity during the on and off phases of the pulse cycle revealed that the initial high-energy air front leads to the formation of leading vortices, and their interaction with the ambient air enhances the mixing process and lateral jet spreading. To examine the effect of inlet air temperature on the formation of unsteady flow structures and vortex evolution, two inlet temperatures of 300 K and 400 K were considered. The results showed that increasing the inlet air temperature led to approximately a 16% increase in the peak velocity of the leading vortex and about a 12% reduction in the trailing vortex velocity. Moreover, the maximum turbulent kinetic energy in the hot jet was about 34% higher than that in the reference case, indicating intensified velocity fluctuations and enhanced mixing intensity in the near-field region.
Keywords
Pulsed Jet
Numerical Modeling
Unsteady Turbulent Flow
Entrainment
Temperature Effects
[[1] S. C. Crow and F. H. Champagne, "Orderly structure in jet turbulence, " Journal of Fluid Mechanics, vol. 48, no. 3, pp. 547–591, Aug. 1971, doi: https://doi.org/10.1017/S0022112071001745.
[[2] K. Zaman and F. Hussain, "Vortex pairing in a circular jet under controlled excitation. Part 1. General jet response, " Journal of Fluid Mechanics, vol. 101, no. 3, pp. 449–491, Dec. 1980, doi: https://doi.org/10.1017/s0022112080001760.
[[3] O. Rediniotis, J. Ko, X. Yue, and A. Kurdila, "Synthetic jets, their reduced order modeling and applications to flow control," in 37th Aerospace Sciences Meeting and Exhibit, 1999, p. 1000.
[[4] B. Smith, M. Trautman, and A. Glezer, "Controlled interactions of adjacent synthetic jets," in 37th aerospace sciences meeting and exhibit, 1999, p. 669.
[[5] D. P. Rizzetta, M. R. Visbal, and M. J. Stanek, "Numerical investigation of synthetic-jet flowfields," AIAA Journal, vol. 37, no. 8, pp. 919–927, 1999.
[[6] I. Choutapalli, A. Krothapalli, and J. Arakeri, "An experimental study of an axisymmetric turbulent pulsed air jet," Journal of Fluid Mechanics, vol. 631, pp. 23–63, 2009.
[[7] C. Y. Lee and D. B. Goldstein, "Two-dimensional synthetic jet simulation," AIAA journal, vol. 40, no. 3, pp. 510–516, 2002.
[[8] J. O. Dabiri and M. Gharib, "Fluid entrainment by isolated vortex rings," Journal of Fluid Mechanics, vol. 511, pp. 311–331, 2004.
[[9] J. Arakeri, D. Das, A. Krothapalli, and L. Lourenco, "Vortex ring formation at the open end of a shock tube: a particle image velocimetry study," Physics of fluids, vol. 16, no. 4, pp. 1008–1019, 2004.
[[10] W. R. Quinn, M. Azad, and D. Groulx, "Mean streamwise centerline velocity decay and entrainment in triangular and circular jets," AIAA journal, vol. 51, no. 1, pp. 70–79, 2013.
[[11] A. Capone, A. Soldati, and G. P. Romano, "Mixing and entrainment in the near field of turbulent round jets," Experiments in fluids, vol. 54, no. 1, pp. 1434-1447, 2013.
[[12] A. Hashiehbaf and G. Romano, "A phase averaged PIV study of circular and non-circular synthetic turbulent jets issuing from sharp edge orifices," International Journal of Heat and Fluid Flow, vol. 82, p. 108536, 2020.
[[13] G. Romano, "Large and small scales in a turbulent orifice round jet: Reynolds number effects and departures from isotropy," International Journal of Heat and Fluid Flow, vol. 83, p. 108571, 2020.
[[14] Z. Zhang, D. Seth, S. K. Artham, J. G. Leishman, and E. P. Gnanamanickam, "Time-resolved flowfield measurements of momentum-driven pulsed transient jets," AIAA Journal, vol. 56, no. 4, pp. 1434–1446, 2018.
[[15] S. Marzouk, N. Hnaien, W. Aich, N. Alshammri, and L. Kolsi, "Effect of pulsation on flow and thermal characteristics of a wall jet," International Communications in Heat and Mass Transfer, vol. 138, p. 106382, 2022.
[[16] K. M. Rabbi, J. Carter, and S. A. Putnam, "Understanding pulsed jet impingement cooling by instantaneous heat flux matching at solid-liquid interfaces," Physical Review Fluids, vol. 5, no. 9, p. 094003, 2020.
[[17] G. C. Saliba, A. Batikh, S. Colin, and L. Baldas, “Pulsed Impinging Jets for Heat Transfer: A Short Review,” ASME Journal of Heat and Mass Transfer, vol. 145, no. 11, p. 110801, Jun. 2023.
[[18] S. Abdolahipour, M. Mani, and A. S. Taleghani, "Parametric study of a frequency-modulated pulse jet by measurements of flow characteristics," Physica Scripta, vol. 96, no. 12, p. 125012, 2021. doi: https://doi.org/10.1088/1402-4896/ac2bdf.
[[19] S. Abdolahipour, M. Mani, and A. Shams Taleghani, "Pressure improvement on a supercritical high-lift wing using simple and modulated pulse jet vortex generator," Flow, Turbulence and Combustion, vol. 109, no. 1, pp. 65–100, 2022. doi: https://doi.org/10.1007/s10494-022-00327-9.
[[20] S. Abdolahipour, M. Mani, and A. Shams Taleghani, "Experimental investigation of flow control on a high-lift wing using modulated pulse jet vortex generator," Journal of Aerospace Engineering, vol. 35, no. 5, p. 05022001, 2022. doi: https://doi.org/10.1061/(ASCE)AS.1943-5525.0001463.
[[21] S. Abdolahipoor , A. Mardani, A. Shams Taleghani, "Effects of pulsed counter flow jets on aerothermodynamics performance of a Re-Entry capsule at supersonic flow," Aerospace Knowledge and Technology Journal, vol. 5, no. 1, pp. 55-65, 2016. (In Persian)
[[22] A. Fallahian, A. Shams Taleghani, and K. Esmailpour, "Three-dimensional numerical study of the effect of blowing angle on the aerodynamic characteristics of a wing section with NACA 0012 airfoil," Aerospace Knowledge and Technology Journal, vol. 12, no. 1, pp. 221–238, 2023. (In Persian)
[[23] A. S. Taleghani, A. Hesabi, and V. Esfahanian, "Numerical study of flow control to increase vertical tail effectiveness of an aircraft by tangential blowing," International Journal of Aeronautical and Space Sciences, vol. 26, no. 2, pp. 785–799, 2025. doi: https://doi.org/10.1007/s42405-024-00826-1.
[[24] S. Abdolahipour, "Effects of low and high frequency actuation on aerodynamic performance of a supercritical airfoil," Frontiers in Mechanical Engineering, vol. 9, p. 1290074, 2023,  doi: https://doi.org/10.3389/fmech.2023.1290074.
[[25] E. Najafi, A.