The Home Machinist!

Congratulations! My 2 cents! The coal burning system of a steam locomotive is a prime example of a closed loop control system: more exhaust steam releases more energy from the coal bed. In a gas or fluids system the control loop is by hand, so no closed loop control anymore! Then, the calorific valu...

Before applying something drastic like a Lempor, you better lean back and contemplate why this is working at all! It is the momentum from the jet that entrains the gases and expels them at the chimney top. If you want to improve there is a solution which comes from the textbooks on fluid dynamics. A...

It is a pity that the second video gives such a poor explanation of the improved draft of a Lempor. This has little to do with whatever Dante Porta or Nigel Day stated, but has everything to do with the explanations of Buckingham of 1913(!!) as treated in a proper text book in fluid dynamics. Kind r...

Since others might be interested: https://www.researchgate.net/publication/320756980_On_the_calculation_of_steam_locomotive_front-end_performance and for the multiples: https://www.researchgate.net/publication/343694913_On_the_calculation_of_steam_locomotive_front-ends_with_more_than_one_exhaust_ori...

Hi Andrew, Thanks for the quick reply! Let there be no doubt that the Lempor is working properly. However, contrary to the believers, I am of the opinion that it is not the ultimate design. A multiple orifice is an example of Buckinghams 1913 explanation of the functioning of models: if a chimney an...

"The LemPor Ejector is by far the more efficient and better front end, thermodynamically."
That is an opinion and not the result of proper scientific testing. Also the Lempor does not comply with the general ideas as taught in fluid dynamics!
Kind regards
Jos Koopmans

Given your emphasis on performance and sound, I am wondering why you did no go any further and replaced the single orifice by a multiple one, say BigBoy style. The theory behind this is discussed in any modern textbook on fluid dynamics. I.e. four orifices give identical performance with 4 scaled ch...

...... There are many differences between the multi port blast nozzle ejector system and the single port- chiefly the multi-port exhaust surface area is over twice as large as single port versions...... Regards, Glenn Rereading the thread this quote surprised me. Did you ever mathematically check t...

Before fabricating anything one should realize why this works at all. Basically a double chimney with 8 orifices is to be regarded as a bundle of 8 scale models of a single large chimney. The original explanation was already given by Mr Buckingham in 1913 and is covered by many pages in modern textb...

For what it is worth, I used an orifice length of twice its diameter. As for their inclination, during the tests of Michaels front-end we found that the inclination that is mentioned by Lempor lovers choked the performance. I would like to suggest that a four-orifice unit should be seen as a bundle ...

Hi all, The report of the Committee on Locomotive Front Ends of the Master Mechanics Ass. of 1906 is also on line: https://babel.hathitrust.org/cgi/pt?id=mdp.39015012686153&view=1up&seq=253 This shows the diminished performance of petticoats. The other book of Goss is Locomotive Sparks, also...

About the four nozzles, it does not make sense to position them on the same level as a single orifice. The optimal distance is about 6-7 orifice diameters, so with 4 orifices they are closer to the chimney entrance. As for the petticoats, I wonder why nobody cares to look again at the Goss experimen...