Diffusion Froude number

For large Froude numbers, the diffusion flame height is momentum-controlled and v = v0. However, most laminar burning fuel jets will have very small Froude numbers and v = vbj that is, most laminar fuel jets are buoyancy-controlled. 

Fig. 11.9 Relative length of a hydrogen diffusion flame stream versus the Froude number d = 1.5-51.7 mm [24] d = 686 mm [25]...

Froude number Fr = Irigd, where U - fuel flow velocity on a burner rim, d -burner diameter, g - acceleration of gravity. The Froude number is used for processing experimental data on diffusion flame length. 

Figure 3.10 Contour lines represented by the ratio (v), defined as the diffusive salt transport (tidal driven) to the total landward salt flux as related to contours of Froude [Fm = Uf/(ghAp/p)1/2] Richardson numbers [Rig = (g[Ap/p][U( /b])/U ]. A clear decrease is found when moving from Type 1 to Type 3 estuaries (From Fisher, 1976, as modified by Jay et al., 2000, with permission.)...

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