Oscillations in the near field of a heated two-dimensional jet
- 1 October 1993
- journal article
- research article
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 255 (-1), 323-347
- https://doi.org/10.1017/s0022112093002502
Abstract
A two-dimensional hot-air jet is investigated experimentally in the transitional regime. The density effect on the near-field behaviour of the initially laminar jet is explored by flow visualization, mean flow measurements and spectral analysis of fluctuating data. It is shown that the broadband amplitude spectra which characterize cold jets become line-dominated for hot jets when the ratio of the jet-exit to the ambient density is below approximately 0.9. Below this critical density ratio the oscillations in the hot jet are shown to be self-excited. That is, the onset of the global oscillations is identified as a Hopf bifurcation and the critical parameter is determined from amplitude spectra and autobicoherence, with the latter proving to be more reliable. Furthermore, the development of three-dimensional structures, which contribute to the jet spreading, is revealed by flow visualization. It is found that, for the parameters investigated, the spreading of the two-dimensional hot jet is not as spectacular as in the axisymmetry case.This publication has 20 references indexed in Scilit:
- Mixing by side jets’’ in strongly forced and self-excited round jetsPhysics of Fluids A: Fluid Dynamics, 1991
- The bifurcation of a hot round jet to limit-cycle oscillationsPhysics of Fluids A: Fluid Dynamics, 1991
- A Frequency Selection Criterion in Spatially Developing FlowsStudies in Applied Mathematics, 1991
- The effect of nonuniform density on the absolute instability of two-dimensional inertial jets and wakesPhysics of Fluids A: Fluid Dynamics, 1990
- Local and Global Instabilities in Spatially Developing FlowsAnnual Review of Fluid Mechanics, 1990
- The spreading of self-excited hot jets by side jetsPhysics of Fluids A: Fluid Dynamics, 1989
- Bénard-von Kármán instability: transient and forced regimesJournal of Fluid Mechanics, 1987
- Perturbed Free Shear LayersAnnual Review of Fluid Mechanics, 1984
- Measurements of nonlinear interactions during natural transition of a symmetric wakePhysics of Fluids, 1983
- Influence of the velocity ratio on the spatial instability of mixing layersPhysics of Fluids, 1982