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Seminars

Integral solutions for some turbulent quantities of small-scale hydrogen leakage: non-buoyant and buoyant jets

Hold Date
2008-10-21 15:30〜2008-10-21 17:00
Place
Hakozaki campus, Science Building no.3, room 3311
Object person
 
Speaker
M.F. El-Amin (九大工学研究院/South Valley University) 金山 寛 (九大工学研究院)

summary:
Throughout this presentation some physical turbulent properties of the non-buoyant (momentum-dominated) jet buoyant jet (plume) of small-scale hydrogen leakage are obtained. The integral method was used to derive the cross-stream velocity, Reynolds stress, the dominant turbulent kinetic energy production term, turbulent eddy viscosity and turbulent eddy diffusivity. Also, both the turbulent Schmidt number and the correlation of the normalized jet-feed material density and the normalized  momentum flux density are estimated. The experimental results for the turbulent buoyant hydrogen-air jet given by Schefer et al. and other literature are used to be inserted in the integral method. Some empirical Gaussian expressions for the mean streamwise velocity and concentration with their associated coefficients of the turbulent buoyant hydrogen-air jet are integrated with the governing equations to obtain the unknown turbulent terms. It is well known form literature that the centerline velocity is proportional with (for non-buoyant jet and for buoyant jet) while the centerline concentration is proportional with (for non-buoyant jet and   for buoyant jet).
The hydrogen-air buoyant jet is comparable with other variable density jets such as helium-air jet as an example of the buoyant jets, while, the momentum-dominated regime or non-buoyant hydrogen-air jet is compared with the air-air jet as an example of non-buoyant jets.
Keywords: Hydrogen leakage; buoyant jet; non-buoyant jet; turbulent Schmidt number; integral method.