Low kinetic-energy loss oscillating-triangular-jet nozzles

Abstract

A visualisation experiment and measurements with a Pitot probe show that natural instability of a partially confined triangular jet can produce a continuously oscillating flow. The device which produces this flow consists of a triangular inlet orifice expanding into a short axisymmetric chamber. There is a small lip at the exit of the chamber. An oscillating-jet flow occurs over a wide range of chamber lengths and expansion ratios. The initial spreading angle of the jet flow is much larger than that of a basic turbulent jet flow. The external oscillating jet has preferred azimuthal directions which are aligned with the corners of the triangular orifice. Kinetic-energy loss coefficients of the oscillating triangular jet are significantly lower than those of an axisymmetric “precessing-jet” nozzle.