Keenans method of estimating divergence ratio

Keenan classified the nozzles according to their nominal divergence ratio , a figure described as arbitrary 

For the three nozzles of smaller diveigence, the nominal exit area was taken at the section C-C, so that the nominal diveigence ratio was  

Now taking the exit area at the section B-B rather than C-C seems physically more intuitive for all the nozzles, since B-B represents the limit of physical constraint on the flow. Therefore we shall define a new term, the physical divergence ratio , as  

Calculations for all four convergent-divet gent nozzles based on the engineering drawings contained in Keenan s paper allowed Table A6.2 to be drawn up. 

Nominal divergence ratio Physical divergence ratio 

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