Published online by Cambridge University Press: 04 July 2016
In their paper, “A Theory of the Cylindrical Ejector Supersonic Propelling Nozzle”, Pearson, Holliday and Smith analysed the conditions under which two unmixed streams of air pass together through a nozzle. Two criteria were used to determine the flow conditions at the exit, when the nozzle is choked: —
(a) That the stagnation pressure in the secondary (subsonic) jet should be a minimum for a given flow quantity.
(b) That the velocity of propagation of small plane waves at the exit should be zero.
Either criterion, applied independently, led to the same result but, as the authors observed, neither has the status of an axiom in fluid mechanics, and a direct proof without invoking either would be preferable.