Modeling of self-oscillations and a search for new self-oscillatory flows

Abstract

A possible mechanism of self oscillations in flows with shock waves and contact disconti nuities is studied. Flows are investigated in the heliosphere, near a blunt cone in an inhomogeneous stream, and in the vicinity of a blunt cylinder with an outflowing supersonic jet, which is supposed to be, according to this mechanism, of a self oscillatory nature. Two dimensional Reynolds equations with algebraic turbulent viscosity are solved by the implicit third order Runge-Kutta scheme. The results of numerical studies are presented.

Numerical Simulations of Self-Oscillatory Flows near Blunted Bodies, Giving off Opposite Jets

“…We construct and investigate flows, containing "active" elements. Particularly, flows near blunted bodies (cylinders or cones), giving off opposite jets, were discovered to have unsteady regimes [14,16]. Here these investigations are continued.…”

“…A jet impinging on a plane [6][7][8][9][10][11][12][13][14] is another type of compressible jet unsteady flows. Self-oscillations main frequencies are studied in [6][7].…”

“…Self-oscillations main frequencies are studied in [6][7]. Numerical flow field simulations are carried out in [8][9][10][11][12][13][14]. The numerical approach LES is used in [10][11][12].…”

“…Possibility of the disturbances amplification by contact discontinuities is a result of the Kelvin-Helmholtz instability and is accepted. Inclusion of intersection points to a list of amplifiers [13][14] is initiated by the known possibility to operate types of the shock reflection from a plane (Mach or regular type) by small influences. If small influences yield significant change of the flow in the reflection zone, then this flow structure is an amplifier of disturbances.…”

“…The numerical approach LES is used in [10][11][12]. RANS, added by an algebraic turbulence model, are used in [13][14]. An impinging of a supersonic underexpanded jet, surrounded by a subsonic stream, on a blunted cone, was found also to have self-oscillatory regimes [15].…”