Investigation into the turbulence statistics of installed jets using hot-wire anemometry

Abstract

This work presents a detailed study of theturbulence flow statistics of a jet mounted with its axisparallel to a rigid flat plate. Hot-wire constant tem-perature anemometry has been used to measure thesingle-point and two-point statistics of the axial velocitycomponent at several locations within the jet flow field.Results show that the jet mean flow near the plate sur-face is subjected to a local acceleration and redirectiondue to a Coand ̆a-type effect. The propagation of theseeffects downstream of the plate trailing edge are stronglydependent on the plate position. Regarding the velocityfluctuations, the mean turbulence intensity levels areseen to decrease as the radial distance between the jetand surface decreases. Analysis of the single-point powerspectral density data on the shear layer close to the plateshows that the reduction in magnitude of the low fre-quency content of the energy spectrum is responsiblefor the decrease in turbulence intensity. Additionally,the characteristic time and length-scales computed fromtwo-point measurements reduce as the plate is mountedcloser to the jet centre-line. The axial eddy convectionvelocity is seen to increase in the region of high turbulentkinetic energy in the shear layer adjacent to the surface.Empirical models for turbulence characteristic scalesand eddy convection velocity are presented. These find-ings suggest that both the amplitude and distributionof the jet mixing noise sources are affected when closelyinstalled next to a surface. This paper is a continuationof a recent investigation on the turbulence statistics ofisolated jets presented in Proen ̧ca et al. (2019)

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ORCID for Anderson Ramos Proenca: orcid.org/0000-0002-4002-1805

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