The bifurcation of a hot round jet to limit-cycle oscillations

The onset of self‐excited or limit‐cycle oscillations in an axisymmetric hot jet is studied experimentally as the jet density is systematically decreased below the value at which absolute instability first appears in the potential core region. By transient measurements at different supercritical jet densities, this bifurcation is demonstrated to be of the Hopf type. That is, close to the critical density, the oscillation amplitude at a fixed point in space is shown to be described by a Landau equation. All coefficients of the equation, i.e., linear temporal growth rate, linear frequency, and the Landau constant, are determined.