Experimental investigation of nonlinear instabilities in annular liquid sheets

2012 ◽  
Vol 691 ◽  
pp. 594-604 ◽  
Author(s):  
D. Duke ◽  
D. Honnery ◽  
J. Soria
Keyword(s):  
Experimental Investigation ◽  
Shear Layer ◽  
Hilbert Transform ◽  
Liquid Sheet ◽  
Nonlinear Instability ◽  
Shear Layer Instability ◽  
Free Shear Layer ◽  
Liquid Sheets ◽  
The Hilbert Transform

AbstractThe aerodynamically driven annular liquid sheet exhibits a complex nonlinear instability. Novel interfacial velocimetry experiments suggest that two distinct physical sources of instability may be present. The first is the well-known free shear layer instability, which is quasi-sinusoidal and nonlinear. The second is a distinct nonlinear rupturing instability, modulated on the previous one. It may be directly driving primary atomization. This instability has not been previously observed in isolation and is inherently nonlinear and non-sinusoidal. Novel application of Koopman analysis and the Hilbert transform permit investigation of these distinct instabilities. A greater understanding of the rupturing instability may lead to a better understanding of atomization phenomena.

scholarly journals Instability patterns between counter-rotating disks

2003 ◽  
Vol 10 (3) ◽  
pp. 281-288 ◽  
Author(s):  
F. Moisy ◽  
T. Pasutto ◽  
M. Rabaud
Keyword(s):  
Aspect Ratio ◽  
Shear Layer ◽  
Particle Image ◽  
Shear Layer Instability ◽  
Free Shear Layer ◽  
Rotating Disks ◽  
Height Ratio ◽  
Aspect Ratios ◽  
Image Velocimetry ◽  
Local Reynolds Number

Abstract. The instability patterns in the flow between counter-rotating disks (radius to height ratio R/h from 3.8 to 20.9) are investigated experimentally by means of visualization and Particle Image Velocimetry. We restrict ourselves to the situation where the boundary layers remain stable, focusing on the shear layer instability that occurs only in the counter-rotating regime. The associated pattern is a combination of a circular chain of vortices, as observed by Lopez et al. (2002) at low aspect ratio, surrounded by a set of spiral arms, first described by Gauthier et al. (2002) in the case of high aspect ratio. Stability curve and critical modes are measured for the whole range of aspect ratios. From the measurement of a local Reynolds number based on the shear layer thickness, evidence is given that a free shear layer instability, with only weak curvature effect, is responsible for the observed patterns. Accordingly, the number of vortices is shown to scale as the shear layer radius, which results from the competition between the centrifugal effects of each disk.

Break-Up Length and Spreading Angle of Liquid Sheets Formed by Splash Plate Nozzles

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
M. Ahmed ◽  
N. Ashgriz ◽  
H. N. Tran
Keyword(s):  
Experimental Investigation ◽  
Flow Velocity ◽  
Liquid Sheet ◽  
Operating Conditions ◽  
Nozzle Diameter ◽  
Empirical Correlation ◽  
Liquid Viscosity ◽  
Liquid Sheets ◽  
Break Up ◽  
Semi Empirical

An experimental investigation is conducted to determine the effect of liquid viscosity and density, nozzle diameter, and flow velocity on the break-up length and spreading angle of liquid sheets formed by splash plate nozzles. Various mixtures of corn syrup and water were used to obtain viscosities in the range of 1–170 mPa s. Four different splash plate nozzle diameters of 0.5 mm, 0.75 mm, 1 mm, and 2 mm, with a constant plate angle of 55 deg were tested. The liquid sheet angles and the break-up lengths were measured at various operating conditions. An empirical correlation for the sheet spreading angle and a semi-empirical correlation for the sheet break-up lengths are developed.

A note on nearly two-dimensional weakly nonlinear instability of an incompressible free shear layer

1999 ◽  
Vol 386 ◽  
pp. 373-377
Author(s):  
A. F. MESSITER ◽  
D. DAVIS
Keyword(s):  
Shear Layer ◽  
Large Reynolds Number ◽  
Nonlinear Instability ◽  
Two Dimensional ◽  
Small Disturbance ◽  
Free Shear Layer ◽  
Weakly Nonlinear ◽  
Instability Waves ◽  
Limiting Case ◽  
Amplitude Growth

The weakly nonlinear amplitude growth of slightly oblique instability waves in an incompressible free shear layer is shown to be first influenced by three-dimensionality in a limiting case for large Reynolds number when a particular order relationship is chosen between the spanwise scale and the amplitude of the small disturbance. The formulation resembles that for purely two-dimensional motion but includes the effect of vortex stretching in the nonequilibrium, nonlinear, viscous critical layer.

Experimental investigation of transitional free shear layer optics

AIAA Journal ◽  
1993 ◽  
Vol 31 (12) ◽  
pp. 2290-2295 ◽  
Author(s):  
Larry Chew ◽  
Walter Christiansen
Keyword(s):  
Experimental Investigation ◽  
Shear Layer ◽  
Free Shear Layer

Model of multicomponent narrow-band periodical non-stationary random signal

2020 ◽  
Vol 2020 (48) ◽  
pp. 17-24
Author(s):  
I.M. Javorskyj ◽  
◽  
R.M. Yuzefovych ◽  
P.R. Kurapov ◽  
◽  
...  
Keyword(s):  
Time Series ◽  
Real Time ◽  
Hilbert Transform ◽  
Spectral Properties ◽  
Narrow Band ◽  
Analytic Signal ◽  
Random Signal ◽  
Hilbert Transformation ◽  
The Hilbert Transform

The correlation and spectral properties of a multicomponent narrowband periodical non-stationary random signal (PNRS) and its Hilbert transformation are considered. It is shown that multicomponent narrowband PNRS differ from the monocomponent signal. This difference is caused by correlation of the quadratures for the different carrier harmonics. Such features of the analytic signal must be taken into account when we use the Hilbert transform for the analysis of real time series.

Sign in / Sign up

Export Citation Format

Share Document