1618 On Oscillation of a Confined Jet with a Downstream Obstacle

Abstract

In the present study, the authors investigate an oscillatory phenomenon of a two-dimensional confined jet with a downstream target, by experiments and computations. By experiments in air and water, jet's frequencies are measured near the target by a hot-wire anemometer and an ultrasonic velocity profiler with a particle-image velocimetry, respectively, at the Reynolds number Re<5000. In computations, the present numerical method is a finite difference method formulated in terms of vorticity and stream function. As a result, we can see the Re effect, the target-distance effect and the target-size effect upon the Strouhal number St. Regarding the Re effect, it is found that there is less influence, which guarantees wide-range workability as a flowmeter or a mixer. All the results can be summarised in empirical formulae describing the relation between St and geometrical parameters.