Reply To: Kylchap Exhaust Systems

[Chris Corney]

Hi Martin, Regarding the “sequential ejector”, for a long time I thought that the various cowls of the Kylchap were slightly convergent, so that the pressure energy in the blastpipe is converted to velocity in a number of small steps. A similar idea to a multi-stage turbine. Looking at drawings and photographs, as far as I can tell, they are parallel, which makes analysis of the deviice a lot easier!
It’s an interesting point about the nozzle peak mach number. According to Wardale’s “Red Devil”, Porta held the view that in some cases it was advantageous to use de laval nozzles. Peak velocity occur at exhaust release which is close to the piston dead centre position, where back pressure doesn’t matter. At mid stroke the nozzles would be operating with subsonic flow conditions imposing a low back pressure on the pistons. This would make best use of the residual exhaust steam pressure.
Chris