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Experiments and modeling of impinging laminar jets at moderate separation distances

Bergthorson, Jeffrey M. and Sone, Kazuo and Mattner, Trent W. and Dimotakis, Paul E. and Goodwin, David G. and Meiron, Dan I. (2005) Experiments and modeling of impinging laminar jets at moderate separation distances. California Institute of Technology , Pasadena, CA. (Unpublished) http://resolver.caltech.edu/CaltechGALCITFM:2005.003

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Abstract

This report describes an experimental and numerical study of impinging, incompressible, axisymmetric, laminar jets, where the jet axis of symmetry is aligned normal to the wall. Particle Streak Velocimetry (PSV) is used to measure axial velocities along the centerline of the flow field. The jet-nozzle pressure drop is measured simultaneously and determines the Bernoulli velocity. The flowfield is simulated numerically by an axisymmetric Navier-Stokes spectral-element code, an axisymmetric potential-flow model, and an axisymmetric one-dimensional streamfunction approximation. The axisymmetric viscous and potential-flow simulations include the nozzle in the solution domain, allowing nozzle-wall proximity effects to be investigated. Scaling the centerline axial velocity by the Bernoulli velocity collapses the experimental velocity profiles onto a single curve that is independent of the nozzle-plate separation distance. Axisymmetric direct numerical simulations yield good agreement with experiment and confirm the velocity profile scaling. Potential-flow simulations reproduce the collapse of the data, however, viscous effects result in disagreement with experiment. Axisymmetric one-dimensional streamfunction simulations can predict the flow in the stagnation region if the boundary conditions are correctly specified. The scaled axial velocity profiles are well-characterized by an error function with one Reynolds-number dependent parameter. Rescaling the wall-normal distance by the boundary-layer displacement-thickness-corrected diameter yields a collapse of the data onto a single curve that is independent of the Reynolds number. These scalings allow the specification of an analytical expression for the velocity profile of an impinging laminar jet over the Reynolds number range investigated of 200 ≤ Re ≤ 1400.


Item Type:Report or Paper (Technical Report)
Additional Information:We would like to thank D. Lang for his contributions to the digital-imaging in this work, as well as G. Katzenstein for his assistance with experimental design and assembly. R. D. Henderson and H. Blackburn provided considerable assistance, as well as the codes that our axisymmetric viscous simulation code is based on. The work was funded by AFOSR Grant F49620–01–1–0006006 and the DOE Caltech ASC Contract W–7405–ENG–48, whose support is gratefully acknowledged.
Group:Graduate Aeronautical Laboratories (Fluid Mechanics)
Record Number:CaltechGALCITFM:2005.003
Persistent URL:http://resolver.caltech.edu/CaltechGALCITFM:2005.003
Usage Policy: You are granted permission for individual, educational, research and non-commercial reproduction, distribution, display and performance of this work in any format.
ID Code:25813
Collection:CaltechGALCITFM
Deposited By: Imported from CaltechGALCITFM
Deposited On:24 May 2005
Last Modified:26 Dec 2012 13:48

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