Coherent structures and wavepackets in subsonic transitional turbulent jets

Yang, Haihua; Zhang, Xingchen; Ran, Ling-Ke; Sun, Daoyuan; Wan, Zhen-Hua

doi:10.1007/s10409-016-0612-0

Cited by 5 publications

(1 citation statement)

References 33 publications

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“…To validate the LEE solver, axial velocity fluctuations for a round jet with Ma = 0.83 at the Strouhal numbers (St) 0.5 are compared with the PSE result [30]. The linear solutions have a free amplitude, which can be adjusted using the inlet amplitude.…”

Section: Validationmentioning

confidence: 99%

Instability waves and low-frequency noise radiation in the subsonic chevron jet

Ran

Wan

et al. 2017

Acta Mech. Sin.

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Spatial instability waves associated with lowfrequency noise radiation at shallow polar angles in the chevron jet are investigated and are compared to the round counterpart. The Reynolds-averaged Navier-Stokes equations are solved to obtain the mean flow fields, which serve as the baseflow for linear stability analysis. The chevron jet has more complicated instability waves than the round jet, where three types of instability modes are identified in the vicinity of the nozzle, corresponding to radial shear, azimuthal shear, and their integrated effect of the baseflow, respectively. The most unstable frequency of all chevron modes and round modes in both jets decrease as the axial location moves downstream. Besides, the azimuthal shear effect related modes are more unstable than radial shear effect related modes at low frequencies. Compared to a round jet, a chevron jet reduces the growth rate of the most unstable modes at downstream locations. Moreover, linearized Euler equations are employed to obtain the beam pattern of pressure generated by spatially evolving instability waves at a dominant low frequency St = 0.3, and the acoustic efficiencies of these linear wavepackets are evaluated for both jets. It is found that the acoustic efficiency of linear wavepacket is able to be reduced greatly in the chevron jet, compared to the round jet.

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Section: Validationmentioning

confidence: 99%