Downstream evolution of proper orthogonal decomposition eigenfunctions in a lobed mixer

Ukeiley, Lawrence; Glauser, Mark; Wick, David P.

doi:10.2514/3.11787

Cited by 31 publications

(16 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The measurement of Yu et al (1995) with initial turbulent boundary layers suggested that the appearance of the high turbulence region at around two to three wavelengths downstream of the trailing edge was a consequence of the positive production of Reynolds stresses; and the flow became more homogeneous at the further downstream stations. Similar conclusions were drawn by Ukeiley et al (1993).…”

Section: List Of Symbolssupporting

confidence: 78%

On the vorticity characteristics of lobe-forced mixer at different configurations

Mao

Zhou

et al. 2009

Exp Fluids

View full text Add to dashboard Cite

Lobe-forced mixer is one typical example of the passive flow controllers owing to its corrugated trailing edge. Besides the spanwise Kelvin-Helmholtz vortex shedding, streamwise vortices are also generated within its mixing layer. The geometrical configuration of the lobe significantly affects these two types of vortices, which in turn affects the mixing performance of the mixer. In the present investigation, characteristics of mixers with five different configurations were examined and evaluated for two velocity ratios (r = 1, 0.4). The mixers have only one lobe in order to eliminate any possible interactions between neighboring vortices generated by the adjacent lobes. Hotwire anemometer was used to examine the Kelvin-Helmholtz vortices via the spectrum analysis while laser Doppler anemometer was employed to examine the streamwise vortices. It was found that there were two main frequencies for the Kelvin-Helmholtz vortices in the wake of the mixer; and the Strouhal numbers approached their respective maximum values at high Reynolds number. The rectangular mixer had similar mixing performance with the semicircular one; and both of them were better than the triangular mixer. The scalloping modification enhanced mixing by generating additional streamwise vortices while the scarfing modification could not improve the mixing performance. C I Mean streamwise circulation of the plane I, List of symbolse Penetration angle (half divergence angle) of the lobe-forced mixer k Wavelength of the lobe (m)

show abstract

Section: List Of Symbolssupporting

confidence: 78%

On the vorticity characteristics of lobe-forced mixer at different configurations

Mao

Zhou

et al. 2009

Exp Fluids

View full text Add to dashboard Cite

show abstract

“…For fluids and structures, the POD has been effective at producing modes that optimize the signal energy distribution in a set of measured time series. POD has been applied, for example, to characterize spatial coherence in turbulence and structures [1][2][3][4][5][6][7], to evaluate the dimension of the dynamics [3][4][5][6]8], modal interactions [9,10], to produce empirical modes for reduced order models [11][12][13][14][15][16][17][18], and in system identification [19][20][21][22]. The POD is also related to singular value decomposition (SVD).…”

Section: Introductionmentioning

confidence: 99%

A complex orthogonal decomposition for wave motion analysis

Feeny

2008

Journal of Sound and Vibration

View full text Add to dashboard Cite

A method is presented for decomposing wave motion into its principle components. The basic idea is a complex generalization of proper orthogonal decomposition. The method involves the representation of real oscillatory signals as complex analytic signals. The relationship between complex modes and wave motion is explored. From an ensemble of complex signals, a complex correlation matrix is formed, and its complex eigensolution is the basis of the decomposition (like a complex singular value decomposition).The complex eigenvectors contain standing and traveling characteristics. A traveling index is proposed to quantify the relative degree of traveling and standing in a waveform. A method of dissecting a wave mode into its traveling and standing parts is also proposed. From the complex modes and modal coordinates, frequencies, wavelengths, and characteristic wave speeds can be obtained. The method is applied to traveling and standing-wave examples.

show abstract

“…Paterson [28] was the first to measure the velocity and turbulent characteristics of a lobed nozzle. Ukeiley et al [29,30] and Glauser et al [31] also characterized a planar lobed mixer flow hydrodynamically. Although many important results have been obtained through these investigations concentrated on discovering the underlying physics of the lobed mixing, however, as Oyakawa et al [32] mentioned, few works have been carried out to study the convection coefficient associated with impinging lobed jets.…”

Section: Introductionmentioning

confidence: 95%