Characteristics of Miniature Short-Tube Orifice Flows

Abstract

This paper presents the results of an experimental investigation into the flow characteristics of miniature short-tube orifices of a type commonly used for fuel injection. From measurements of differential pressure and volumetric discharge it is shown that these devices are susceptible to a cavitation-induced instability phenomenon known as hydraulic flip. It was found that this instability is limited to orifices of length less than fourteen diameters and occurs at a critical pressure differential which varies as a function of the orifice l/d ratio and contraction parameter β. In addition, the performance of the device is examined in terms of the head loss characteristics and it is shown that the mechanisms associated with hydraulic flip have a significant effect on the efficiency of discharge.