In Leung's paper "Venting of Runaway Reactions with Gas Generation" AIChEJ 1992, allowance can be made for reduction in design flow arising from mass depletion during the emergency relief process in bubbly flow. The applicable reduction factor is given as (Eq 39)
W/Wmax = 1/(1+ ao^.5)^2...
I've been comparing Fig 2-16 and the table on Page A29 in Crane Tech Paper 410 which both purport to show Kb versus r/d. The Fig 2-16 shows experimental data for Kb versus r/d which starts at values of Kb about 0.35 to 0.4, dips to about 0.2 at r/d = 4 and rises roughly to a plateau at r/d > say...