Inviscid instability characteristics of free shear layers with non-uniform density

Koochesfahani, Manoochehr; Frieler, C. E.

doi:10.2514/6.1987-47

Cited by 8 publications

(1 citation statement)

References 4 publications

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“…Following the procedure of conventional linearized stability calculations similar to that of Koochesfahani & Frieler (1987) and Michalke, the basic flow U is assumed to be two-dimensional and a function only of the cross-stream variable, y. The equations of motion and continuity are made non-dimensional by taking as units of velocity and length the free-stream velocity, U,, and the wake half-width, 6 , where…”

Section: Stability Analysis a Fundamental Question Thatmentioning

confidence: 99%

Experiments on the forced wake of an airfoil

Gharib

Williams-Stuber

1989

J. Fluid Mech.

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Presented here is an experimental effort which attempts to understand the nature of the wake of an airfoil in a controlled environment. The frequency of oscillation in the wake (the vortex shedding frequency) is controlled through the introduction of an external perturbation. Strip heaters are used to introduce waves into the top and bottom boundary layers of a thin symmetric airfoil which are amplified and introduced to the wake. The linear and nonlinear interactions of these waves in the wake are studied in detail. Three modes of interaction have been observed through flow visualization and velocity measurements: frequency locking in which the vortex shedding frequency is the same as the forcing frequency, quasiperiodic vortex interaction in which periodic clusters of vortices are observed in the wake, and chaotic vortex interaction in which the vortices in the wake have a three dimensional random structure.Two points of view are applied in the analysis of the data:1. The effect of forcing on flow parameters such as velocity fluctuations and drag are examined.2. Ideas from nonlinear dynamics (such as Lyapunov e x p e nents and Poincar6 sections) are applied in an attempt to relate the basic physics of the system t o the concepts of mode interaction and chaos.

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Section: Stability Analysis a Fundamental Question Thatmentioning

confidence: 99%

Experiments on the forced wake of an airfoil

Gharib

Williams-Stuber

1989

J. Fluid Mech.

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Numerical solution of the viscous stability equations for low‐speed reacting flows

Mahalingam

1992

Numerical Methods in Fluids

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SUMMARYThe governing equations required to analyse the linear (viscous) stability of low-speed reacting flows are derived and a solution method based on initial value problems is described. The algorithm accurately reproduces the neutral stability curve for a non-reacting viscous shear layer, thus providing partial validation. The results for premixed and non-premixed flames in planar shear layers are presented and discussed.

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Control of Free Turbulent Shear Flows

Fiedler

Flow Control

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Inviscid instability characteristics of free shear layers with non-uniform density

Abstract: The linear spatial instability of two-dimensional two-stream plane mixing layers has been studied extensively in the past. In the case of uniform density, Michalke (1965)

Cited by 8 publications

References 4 publications

Experiments on the forced wake of an airfoil

Experiments on the forced wake of an airfoil

Numerical solution of the viscous stability equations for low‐speed reacting flows

Control of Free Turbulent Shear Flows

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