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Post by Roger on Dec 28, 2018 21:15:51 GMT
Hi Pete, Bob's book is much more analytical than the DAG Brown book, but sadly the descriptions of the diagrams don't make much sense to me. I've created a parametric model in CAD so I could explore the ratios and relationships described in the book, but I can't make it work.
There are two really interesting things in the book that caught my eye. Firstly, the 'End regulation' arrangement seems much more satisfactory to me, and Bob says he uses that exclusively. It avoids the very slender end of the steam cone used in Annular regulation. Secondly, he shows the arrangement of an injector that works with water at higher temperatures.
I'm frustrated that the book so nearly explains the relationship between the different geometries, if only I could make it work. I don't know if Bob is still alive. If he is, it would be great to get his explanation of the text and the diagrams. Failing that, I'll have to go back to basics and try to figure it out for myself which seems pointless since it's all been done before.
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Post by Deleted on Dec 28, 2018 22:12:15 GMT
yes I agree Roger, Bob has presented a number of drawings which don't really teach anything, he's just used them to show what's going on, no dimensions or such. However, I do like what I read and it seems that he's put all of his teachings into practice. When I do something I tend to read what other more learned folk have to say on the subject, see if they agree (roughly) with each other and then follow the one that makes the most sense in my head, this has never let me down before. Bob's words make sense, they mostly agree with others and therefore his charts have now become my baseline, I may step either side of this line as I learn more for myself but not by far keeping within the general parameters.
Pete
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Post by Roger on Dec 28, 2018 22:27:34 GMT
My hope is to be able to create designs using End Regulation using the formulae and proportions given. I'm sure I'm just missing something obvious, maybe you'll spot what it is. It needs a brainstorming session with the book to hand to try to figure it all out. It's not that complicated really.
I intend to use the two valve 'high temperature' variant and also to experiment with some plastic materials for the cones. I've got some Fluorosint for those and I'm itching to get on with it and see how it goes.
Bob seems to be able to make injectors work down to sizes that DAG Brown says aren't feasible, so I'm more inclined to lean on Bob's book.
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Post by Deleted on Dec 28, 2018 22:33:28 GMT
w it goes. Bob seems to be able to make injectors work down to sizes that DAG Brown says aren't feasible, so I'm more inclined to lean on Bob's book. Are you sure Roger?... I'm only about a third into the book but I'm sure that I read a comment from Bob stating sizes below 11 oz aren't really viable due mainly to the size debris which can get stuck... I'm sure that you could go smaller but how often would such a small injector fail? Pete
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Post by Roger on Dec 28, 2018 22:44:17 GMT
w it goes. Bob seems to be able to make injectors work down to sizes that DAG Brown says aren't feasible, so I'm more inclined to lean on Bob's book. Are you sure Roger?... I'm only about a third into the book but I'm sure that I read a comment from Bob stating sizes below 11 oz aren't really viable due mainly to the size debris which can get stuck... I'm sure that you could go smaller but how often would such a small injector fail? Pete Hi Pete, Sorry about that, I'm quoting from memory and I've got it the wrong way round. DAG Brown quotes down to 4Fluid Ounces whereas Bob says 11 is about the minimum. (foot of Page 19) I can't see any issue with small injectors, you just have to filter the water appropriately (and perhaps the steam?)
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Dec 28, 2018 23:23:30 GMT
For a medium sized 'standard' 22-24 oz per minute injector, the stated pipe sizes are 3/16" THIN WALL copper tube for water supply to the injector and exit from the injector, and 5/32" thin wall pipe as the steam supply.
In respect of the discussion above, one must bear in mind that Bob Bramson made 'large' injectors predominantly. There are a number of bits of Bob's published research I would take issue with.
Pete, DAG (Derek) Brown's book you have and really you don't have to go any further IMHO. His book may not be very readable and 'user friendly', but his 18 oz per minute injector drawings and design are very well proven as is his 26 oz per minute injector. Both are based on substantial research and experiment and are extremely good.
All require the above pipe sizes specified.
When you get round to making same I have a few comments on the the 18 oz per min example of Derek Brown.
Bob Bramson's work is readable, but injector design is often far more complicated! You really have to get your head round what Derek Brown states instead of opting for the easier read IMHO.
You don't have to understand any of the physics and maths, if you simply copy Derek Brown's drawings for the 26 oz per min injector (and with a few provisos that I can explain subsequently) the 18 oz per min injector on p.52 of his book.
The Bramson snout of the steam cone I have discussed previously on here, and I am not going to repeat myself here until either you or Roger are tooled up and ready to make same!
Cheers,
Julian
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Post by Deleted on Dec 28, 2018 23:42:56 GMT
Hi Julian
Yes Derek's drawings are more useful and probably what I'll follow but I'll be using Bob's charts for deciding which injectors to fit, both Bob and Derek agree on pipe size although there's no mention of 'thin wall'. From what I understand elsewhere, 1/8th ID is what's needed, this would leave some leeway on 3/16 but yes the 5/32 would need to be thin wall. I'm also looking into metric pipe, it's early stages yet, I have a little time before committing to a given size.
cheers
Pete
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