Large-eddy simulations of chevron jet flows with noise predictions

Xia, Hao; Tucker, Paul G.; Eastwood, Simon

doi:10.1016/j.ijheatfluidflow.2009.05.002

Cited by 107 publications

(89 citation statements)

References 38 publications

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“…The growth and decay for the pressure wavepackets have been clearly demonstrated. Moreover, it is found that the noise is produced from the region near the end of the potential core, and mainly radiates towards shallow polar angles, which are in agreement with experimental and LES results [2,16]. In general, the beam patterns produced by the wavepackets in two jets show no qualitative difference.…”

Section: Acoustic Efficiency Of Linear Wavepacketssupporting

confidence: 85%

“…The two grids give similar profiles implying that current grid resolution is sufficient. Compared with LES and experimental data, the present simulation shows a longer potential core length and faster decay rate beyond the poten- Table 1 The flow conditions of the round and chevron jet [15], filled triangle from Xia et al [16]. The small figure shows the iso-contours ofū z at z = r 0 [13], open circle from Bridges and Brown [1] tial core.…”

Section: Description Of the Baseflowmentioning

confidence: 55%

“…Here, two jets ejected from nozzles designated SMC000 (round nozzle) and SMC001 (chevron nozzle) [1] are considered in stability analysis, which has been investigated by experiments [1], Reynolds-averaged Navier-Stokes (RANS) simulations [15], and large eddy simulations [16,17]. The jets are operated at identical conditions with Mach number Ma = U j /a ∞ = 0.9, Reynolds number Re = ρ j U j D j /μ j = 1.35 × 10 6 , where a ∞ , U j , D j , μ j are far-field speed of sound, jet exit velocity, diameter, and viscosity, respectively.…”

Section: Description Of the Baseflowmentioning

confidence: 99%

“…As addressed in Refs. [3,16,31], the noise radiation of round and chevron jets at shallow polar angles is all dominated by low-frequency components, and thus we here plot the growth rates of instability waves in the chevron jet SMC001 in the frequency range of St = ωD j /U j = 0.2 − 0.7 at four different streamwise locations z/r 0 = 0.5, 1.0, 2.0, 3.0. Meanwhile, the growth rates of round jet SMC000 at the same locations and frequencies are also presented for comparison.…”

Section: Spatial Evolution Of Instability Wavesmentioning

confidence: 99%

“…Since chevron jets mainly reduce low-frequency noise at shallow polar angles [16,17,31], we currently select an instability wave at St = 0.3 as a typical example to investigate the spatial development and acoustic efficiency. As discussed before, although the chevron jet has multiple unstable modes, only the third mode is unstable as z 3.0 and related to acoustic emission.…”

Section: Acoustic Efficiency Of Linear Wavepacketsmentioning

confidence: 99%

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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: Acoustic Efficiency Of Linear Wavepacketssupporting

confidence: 85%