New Mills Pumping Station

[john mills]

Hi
this has been a fascinating project .i wonder if tipping water in from a bucket causes too stronger currents that
the vains cannot guide the flow properly .could you block of the out let and fill the tank.then unblock the out let
and see if the flow is more like what happens at the river.on the full size.the sluce gate may control the flow as more as desired.
John   

[steam guy willy]

Hi John , thanks for the advice and I will see what else I can do ..

Thanks

[steam guy willy]

I have now been thinking about making this work and have decided to make the water way flow more like the real thing .. I have been making it all out of perspex and will need to find a good flow of water . If I was able to find a source of practical
fluid dynamics info that would be good ... So ..I have quite a few 4 BA screws to tap and I have used this drill to achieve this ..also I have this screwdriver to quickly get the screws in ... I have also been busy blocking up the broken windows of the local  sewerage pumping station  with sheet steel to stop all the kids and people breaking in and smashing the place up ....

Willy

[MJM460]

Hi Willy, it sounds like you have been busy at the museum.

I’m sorry to hear that you have not made more progress on getting the turbine working.  I think you are on the right track, having a look at the fluid mechanics, although the right books on the subject are pretty heavy going.  Someone may have a more readable suggestion than the ones I have.

Let me try and make a brief Summary.

Basically, I think you will find the important clues in two of the drawings you have posted, in particular in your post #55 and post #53.

The one in #53, image 2738, shows the key stator section.  Those gates and vanes form the inlet nozzles to the turbine.  I know they are rectangular, but that section shows the smooth transition through an ever decreasing passage width, with sharp edges and shaped for a smooth flow, and directed into the cups of the rotor in a smooth manner.  The water flowing through these gates is accelerated to much higher velocity than the water in the broader inlet channel.  This jet of water has considerable momentum, and the rotor cups deflect the stream and direct it down and back.  The change of momentum (momentum is a vector, so change of direction is a change of momentum) causes a force on the rotor cup so the rotor rotates.  Think about the jet out of a hose nozzle if you try and deflect it with your hand or a flat board.  Turning the jet 180 degrees with a cupped hand or bowl gives more force than changing the direction 45 or 90 degrees with a flat plate.

To show how important the velocity of the stream is, it is interesting to discover that when a full size hydro turbine is being slowed by closing the gates, the rotor initially spins faster due to the increased velocity, before it eventually slows due to the reduced water mass flow when the gates  close further, especially if the turbine is not loaded.  Really upsetting for the young engineer who meets the issue for the first time.

When I look at the diagram in post #55, I see the important shape and direction of the stator parts that form those nozzles, it looks pretty good to me.  Compare the cross section of your gates with that sketch.

When I look at the sketch in post 53, image 2207, you have shown the direction of the water flow into the rotor, but the blade angles in that sketch are not consistent with that sending that water in that direction.  The components you have labeled “flumes” in that sketch appear to be directing the jet radially inwards, so most of the force will just be against the central shaft.  Just as much force, but not as good at producing rotation.  Some gates may actually be trying to turn the rotor backwards, depending on the exact spacing.  I’m not sure which sketch best represents your stator parts as you have made them.

I think your rotor looks pretty good, I think if you can get the inlet gates and guides to send a jet in the right direction, it will go well.  That was a huge amount of work, and I think the shape is pretty good.

Remember Newton’s observation/law that a body continues in a state of uniform motion in a straight line unless acted upon by an external force.  It is momentum that is the property that quantifies how much force is required.  Momentum is mass times velocity.  That Newton’s law is now expressed as the law of conservation of momentum, which is as universally true as the law of conservation of energy.

The key is to maximise the mass times velocity of the water, and direct it in the right direction against the cups of the wheel.

I hope that is a help to your understanding of how the turbine works.  I am sure you will have questions, but let me know if it makes sense.

MJM460

[steam guy willy]

Hi MJM,Thanks for this ..really interesting and informative ... the design of these turbines date back to the late19th century so although they had all the maths they possibly were not able to comprehend all the finer points of fluid dynamics..?  So I am making the sluice parts with my Meccano to the dimensions of the full size prototype but I dont know about scaling everything down ?? there is quite a lot of space around the turbine but this could be filled in if necessary

Willy

[RReid]

Hi Willy. Your red handled brace is just like the one I have, which had originally been owned and used by my carpenter/cabinet maker Great-grandfather. It's served me well, most often as a cordless screwdriver as in your pic.

[steam guy willy]

Hi Ron , yes old tools are cool and I have been collecting all my life ?!!!!   So more work on the almost finished sluice  and the advantage of using perspex and Meccan is that you can see where to drill the holes !! I have been comparing some of the old drawings and there are quite a few differences between them ..so we will see what happens ... I might wait for a thunderstorm to produce a constant steady water flow !!

[steam guy willy]

More work on the sluice box and it needs sealing to be water tight. I shall take it to the local carwash and use the high pressure water hose to see if that will make the turbine rotate ??  also I have got a couple of flywheels to modify for the engine set up

Willy

[steam guy willy]

I have started on the flywheels and there are a pair of compressors driven from the turbines.. However the pairs only seem to have one that has an extra balancing part between two of the spokes ??  also on one set the balanced wheel is the one closest to the turbine unlike the other set where it is furthest from the turbine ??  I can only visit the building occasionally so I will have a look to see if the compressors are 'handed'..!! and the balance weight is on the other side ??

Willy

[crueby]

The balance weights are interesting, I can see them on three of the four flywheels.


A fascinating project!


 

[crueby]

Just looked back at your early posts on this build. If you look in img_122 and img_133, the two together show all four flywheels have counterbalance weights. Two at the top, one on the left, one on the right sides vertical.

[steam guy willy]

Hi Chris , Yes you are right.. There must be some explanation for this ...It may be that the connections on the crankshafts have been disconnected at some point ?!! it is now 4 am over here so will look closer tomorrow !!
Thanks
Willy.

[Roger B]

If they are two cylinder reciprocating compressors I would expect the cranks and hence the balance weights to be at 90°. Each flywheel will counterbalance the crank nearest to it.

[steam guy willy]

Hi Roger, thanks and yes I can see that now ..this is the same on a locomotive of course where the driving wheels share the same axle..
I am now profiling the flywheels with files of course !!  One of them has this strange defect that looks as though there is a break in the spoke , however I have managed to file most of it away ..although there is still some evidence on it ...this will be filled and then painted

Willy

[steam guy willy]

Hi Back to work on the engine  I have been filing the spokes , and there are quite a few hard places so quite difficult to get right ...also I  have been busy getting the MOT for my van  welding  and pop riviting etc etc but it has passed with quite a few advisories !!! and when the chap was filling out the form  he was saying out loud what he was writing... brake hose ...thats normal,  wheel bearing ...thats normal.   oil leak....thats normal    shock absorbers ...thats normal   ?? so when I asked him if he was writing down everything  he said 'oh no ..its just that it is a 56 year old Morris Minor  !!!!

I have also got some gears for the engine but they are 2 mod rather than .6 mod which is more to scale ...

Willy