Title

Hot-Wire Study On The Mean And Turbulent Streamwise Velocity Profiles Following An Axisymmetric Annular Jet

Abstract

Distributions of instantaneous streamwise velocity are measured by hot-wire anemometry following an annular jet. The jet is introduced at the inner radii of a hollow cylinder, open at both ends, tangential to the inner surface. The flow entrains fluid from one end of the cylinder, exiting the opposite end with a distinct annular profile. Profiles presented from the measurements are for the mean and second moment of the streamwise velocity, skewness and flatness factor, intermittency factor, autocorrelation coefficient with varying streamwise distance from the jet, and length scales in the near field region following the jet. Reynolds numbers tested, based off the inner cylinder diameter and maximum jet velocity in the exit plane, range from 72,000 to 273,000 for two different diameter annular jets. It is seen that the jet quickly dissipates momentum to the ambient environment and approaches a self-similar Gaussian profile at a distance of 4 cylinder diameters from the exit plane. This distance is much shorter than a typical development length for an axisymmetric jet, indicating a more relevant near-field length-scale for the streamwise development may be the shear layer thickness of the annular jet. The distance to reach self-similarity corresponds to 50 shear layer thicknesses for the smaller annular jet. Following the merging of the jet, self-similar scaling approaches represent the jet well. At numerous points in the near field region following the exit plane additional data is taken to obtain the energy spectra. It is seen through the energy peak that the relevant length-scales in this region are indeed the shear layer thickness.

Publication Date

9-16-2013

Publication Title

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

Number of Pages

-

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

Socpus ID

84883695596 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84883695596

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