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Effects of oscillation frequency and amplitude on separation in an unsteady turbulent flow by Martin Fox

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Published by Naval Postgraduate School in Monterey, California .
Written in English

Subjects:

  • Aeronautics

Book details:

Edition Notes

ContributionsNaval Postgraduate School (U.S.)
The Physical Object
Pagination1 v. :
ID Numbers
Open LibraryOL25411406M

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T railing-Edge Separation Effects Figure 14 provides a closeup on the trailing edge at one instant in the plunge cycle, for k = 4, h = 0. , fully laminar flow, sho w-. In this paper, the effects of oscillation amplitude on the aerodynamic derivatives of the thin rectangular cylinder with B/D=13 and were was clear that the torsional amplitude affected strongly the aerodynamic derivatives H 2 * and A 2 *.This effect reduced the critical velocity of Cited by: Measurements of the Periodic Velocity Oscillations Near the Wall in Unsteady Turbulent Channel Flow the amplitude ratio is position and frequency dependent. Binder G., Kueny J.L. () Measurements of the Periodic Velocity Oscillations Near the Wall in Unsteady Turbulent Channel Flow. In: Bradbury L.J.S., Durst F., Launder B.E Cited by: This paper presents a numerical study of the effect of oscillation amplitude in oscillatory baffled column (OBC) using computational fluid dynamics. The numerical work was carried out for single phase liquid flow for an unsteady 3-D model using commercial software, Fluent (). This work was concentrated on the effect of oscillation by: 8.

Abstract. Allusions and conjectures about the influence of imposed oscillations on the bursting mechanism in wall flows are not uncommon in the litterature on unsteady turbulent boundary layers or Cited by: 3.   For example, in unsteady flows, we can consider the solution to reach a periodic state when the amplitude of oscillation doesn't change anymore. But when the curve is not sinusoidal, I don't know how to measure the amplitude, and as a result I don't know how should I understand that the solution is reached to a periodic state! Without any damping, the cylinder would oscillate at $\sqrt{ \tfrac{g}{\Delta x} }$ indefinitely but the damping here will alter the maximum $\Delta x$ of each subsequent oscillation. So the amplitude and frequency of oscillations will change in time, i.e., the amplitude will . The objective of this study is to investigate the effects of oscillations in the main flow and the coolant jets on film cooling at various frequencies (0 to Hz) at low and high average blowing ratios. Numerical simulations are performed using LES Smagorinsky–Lilly turbulence model for calculation of the adiabatic film cooling effectiveness and using the DES Realizable k-epsilon Cited by: 1.

distribution, obtained by 60 unsteady pressure sensors mounted into the model. All data were recorded with a sampling frequency of kHz. Hot-film anemometry In order to resolve the unsteady behavior of the boundary layer, the suction side of the wind tunnel model is. A pulsed-plasma jet actuator is used to control the unsteady motion of the separation shock of a shock wave/boundary layer interaction formed by a compression ramp in a Mach 3 flow. The actuator is based on a plasma-generated synthetic jet and is configured as an array of three jets that can be injected normal to the cross-flow, pitched, or pitched and by: There is an oscillation imposed on this uniform flow. The unsteady flow can be represented as: Where: U t = instantaneous velocity, (m/s) U 0 = time averaged velocity, (m/s) f =frequency of pulsation, (Hz) t = time, (s) The goal is to compare the heat transfer before and after the oscillation. Figure 2 shows the schematic of the experiment in. The Strouhal number defined by this oscillation frequency, amplitude, and upstream flow speed of approximately m/s is × 10 −3. From Figure 6 b, in the case of f e = 40 kHz, strong spectra are observed at 30, 40, and 70 kHz. 40 kHz is the same as f e, 30 and 70 kHz are caused by the aliasing effect between the frame rate of the Cited by: 7.