6023

What's happening within the box?
Are you happy to share how you manage the transition from the single passage to 4?

 

3" diameter = 7.07 ins^2
Times 4 = 28.28 ins^2

6" diameter = 28.28 ins^2

(I think?)

Dave

 

Yes, I worked it through. A = pi*d^2 / 4

1. New setup pi * 3^2 / 4 = 9/4pi times 4 orifice's = 9pi.
2. Old setup pi * 6^2 / 4 = 9 pi.

So, the question remains, why is it square??

 

How else do you arrange four holes equidistant around a single centre? Any other arrangement of four orifices would mean that each jet had a different spatial relationship with the chimney opening.(*)

Or have I misunderstood your question?

(*) with the obvious proviso about an arrangement rotated by n degrees about the centre, but in which the four orifices still have a square relationship to each other.

Tom

 

That could be done within a circle.

 

Yes, the runner not the orientation of the orifices. They obviously need to be set out in a square.

What im asking is why the runner is a box tube as oppsed to a cylinder.

 

NO answer yet to the question "which GWR locos were fitted with a Kylchap exhaust?

 

They are in a circle Four points equidistant from a centre have to be located at the corners of a square, but are also all co-incident with a circle centred on the same point.

OK, got you now.

Tom

 

Tom's geometry 101 hahaha

Seriously tho, whats in the box already?!!!

 

I think you missed the sarcasm in @Jimc's post, but to spell it out "What, you mean take concepts first used abroad, first implemented in the UK on a GWR locomotive, and then use them to upgrade an LNER one? I'm sure that could never happen...", the obvious follow on being "except obviously how the LNER A1 was upgraded to an A3 following on technological developments first used in the UK on a GWR Castle".

Tom

 

Easier to manufacture and doesn't affect performance?

Dave

 

It's a welded box, surely a bog standard drawn tube would be cheaper/quicker?


Keith

 

I know they're in a circle but you were answering as to why they were in a square box and you answered "How else do you arrange four holes equidistant around a single centre?"

 

No need to be facetious. It was a genuine question about something that seemed a mystery to me but given the tangled web of railway history may just have been an in treating fact.

 

Exactly. Unless there is something else in there that we dont know about?

Something to condition the flow perhaps?

 

There must be something in that box, or there is a real risk of dead zones in the flow, where fluid collects in the corners.

This is why pipes are usually round as it minimises the surface area and this frictional losses for a given volume.

 

I don't know much about the physics, but it was not just the Gresley A1 but the Gresley V2 which benefitted from the experience of the GWR. V2s were put on test at Swindon post war and one such single chimney example received a copper capped chimney as a result of this.

It had its "Swindon crown" removed swiftly by KJ Cook, who had moved to the Eastern region from the Western, for fear of a backlash from the conservatives amongst the LNER faithful! The photograph of the V2 with the offending chimney can be found in a few publications.

There's also anecdotal evidence that Edward Thompson was greatly influenced in his locomotive engineering by the time he spent living by Paddington Station, whilst works manager of Stratford.

I'm an LNER man through and through, but it is clear if one strives to be objective that the LNER had much to learn from other railways - that could also be aimed of all of the other railways to that found on the continent and elsewhere. Truly, whilst I have a great love of the LNER Pacifics, one cannot but quietly admire the work of Chapelon in particular with his Pacifics and magnificent 4-8-0.

 

Regarding the blast pipe, it is tapered, so a round construction would cost more than four identical flat sides. Moreover both
at the bottom and the top there should be space for mounting bolts, so after some discussion the choice was made for the
cheapest fabrication, sophistication is for a later date! GWS needed proof that it worked in principle first!

 

The only GWR loco to have carried a Kylchap is 6619. The actual cowling was an old one out of Sir Nigel Gresley. The nozzle was a DeLavel nozzle.

 

Pipes are round because it minimises stress concentrations and hence they last longer. The frictional difference is a nice extra, but less significant than you might imagine. Except with very viscous fluids or long distances the effects of entrance, exit, bends, etc. tends to be more important than friction per se (assuming your pipe is a sensible size to start with).