Flow characteristics of sub- and supersonic jets issued from orifice and notched orifice nozzles, and application to ejector

Abstract

The flow characteristics of sub- and supersonic under-expanded jets issued from circular nozzles have been studied well; however, this does not apply to sub- and supersonic jets from an orifice nozzle. In this study, the flow characteristics of sub- and supersonic jets issued from an orifice or notched special orifice nozzle are examined experimentally based on the results of a visualized flow pattern by the Schlieren method and the measurements of velocity distribution by a thin supersonic Pitot tube. That is, the effects of the nozzle shape on the flow characteristics such as the decay of the jet centerline velocity, velocity distribution at the cross section, increment of the jet- width and -flow rate to the downstream are examined experimentally. Results indicate that the jet issued from the notched orifice nozzle with a rectangular notch demonstrates excellent entrainment performance. In addition, to improve the performance of a cylindrical ejector, the application of the results is examined.

Keywords

• sub- and supersonic jet
• orifice jet
• notched orifice jet
• flow visualization
• entrainment
• ejector
• efficiency