Reply To: Locomotive Exhaust Visualisation
Chapter 12.1 of Applied Gas Dynamics by Ethirajan Rathakrishnan and published in 2010. Gives an explanation.
There has been lots of work on understanding the physics of jets because of their applicability in a number of fields.
The chapter goes onto explain why ‘Goodfellow Tips’ work.
Through practical experience steam locomotive engineers developed solutions that worked and it is only now through research in other fields that we are starting to understand how they work.