Preliminary study of oscillating triangular jets

Abstract

A visualisation experiment and measurements with a Pitot probe show that fluidic 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 with an exit lip. These oscillations occur over a wide range of chamber lengths and expansion ratios. The amplitude of oscillation and the initial spreading angle of the jet flow are much larger than that of a simple jet flow. The external oscillating jet has preferred azimuthal directions which are aligned with the corners of the triangular orifice. The energy loss coefficient of these jets is significantly lower than what can be achieved from a precessing circular jet.