Reply To: Kylchap Exhaust Systems
The way I come to that problem is that the mass flow ratio in a locomotive is not in a very good place for efficiency in a jet pump. Obviously, we can’t change the mass flow ratio very much, coal combustion does what it does.
That being the case, one way of overcoming that is to stage the pump, so we have a blast pipe that entrains a small proportion of the flue gas flow, this then feeds to another stage where the flow entrains another load of flue gas, and so on. Each stage is thus working at a more favourable mass flow ratio.
If the flow in each Kylchap petticoat is being used to drive another stage, then we do not want to decelerate the flow, as we need that velocity energy to drive the following stage. Hence we could either use a slightly converging or parallel petticoat.
P.S. Glad to have stirred things up a bit!