Stability and mixing of submerged turbulent jets at low Reynolds numbers
Name
MIT-EL-75-014-02191981.pdf
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3.28 MB
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Adobe PDF
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Author(s)
Ungate, Christopher David
Harleman, Donald R. F.
Jirka, Gerhard Hermann
Date Issued
1975
Publisher
MIT Energy Lab
Series/Report no.
MIT-EL
75-014
Abstract
An experimental study is made of the variation of volume
and centerline dilution as a function of Reynolds number in non-
buoyant and buoyant round jets discharged vertically from a submerged nozzle. The jet Reynolds numbers covered the laminar-
turbulent transition with values ranging from Re = u D/v = 100
to 20,000 where u = jet exit velocity, D = jet diameter, and
V = kinematic viscosity. Measurements of jet temperature profiles
are obtained by using both fast and slow thermistor probes.
Turbulent dilution is found to be independent of Reynolds
number for non-buoyant jets above a critical Reynolds number of
about 1,500. For buoyant jets (densimetric Froude numbers in the
range 25 to 50), the critical Reynolds number is about 1,200.
Reasonable agreement is obtained with the results of previous investigators for dilution values at high Reynolds numbers. Dye
studies of transition Reynolds numbers are compared with a study
by A.F. Pearce (1966) and good agreement is found.
The results are useful in determining the minimum length
scale ratio for hydro-thermal model studies, especially those of
submerged multiport diffusers. It is concluded that modeling of
turbulent jets is acceptable provided the model Reynolds number
is larger than the critical Reynolds number and provided no other
constraint becomes binding. In addition, the model jet's laminar
length, if any, must be insignificant when compared to the total
length of the path of the jet.
Description
Originally presented as the first author's thesis (M.S.), Temperature reduction in a submerged vertical jet in the laminar-turbulent transition, M.I.T. Dept. of Civil Engineering
Subjects
Jets -- Fluid dynamics
Thermal pollution of rivers, lakes
Reynolds number
Diffusers
Hydraulic models
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