Member postings for Werner Jeggli

Hello Byron,

Your proposed oil obviously is designed for ambient temperature, for a short sterilisation at 100°C at most, A model steam turbine is supposed to operate at steam of say 4 Bar. The wet steam temperature at this pressure will be 151°C. Your tests therefore should be run with live steam!

I cannot find any information in fhe internet about the temperature behaviour of this proposed oil. I therefore will stick to my well proven Krytox 105.

regards Werner

Hello Mike,

Why don't you use sections of medical injection needles. There is a large variety of sizes. To doctors, they are consumer items and I get them free of charge!

Hello Byron,

Viewing your pictures it appears to me that the quality of the cast is disappointingly low. I compare it with a bronce cast exhaust insert I received from shapeways some time ago. But then, this later item was much smaller.

Perhaps they used a different casting technique ?

Werner

Hi Roger,

You are right of course, but then you will have problems with remote controlling the reversing gear because of unsynchronised tooth positions. In addition it will not be possible to dynamically brake the model with counter steam. I built such a gauge 1 turbine loco drive many years ago - that's why I know.

Am I correct in assuming that the use of the Spencer one sided blower principle to a turbine rotor would result in a bidirectional turbine while your adaptation is uni-directional. Would be a big disadvantage for model applications!

Werner

Byron,

Your having a go at a drag turbine is very commendable and I wish you success. But instead of machining the rotor it would be much simpler to have it lost wax cast by shapeways. It really does not cost that much!

Hello Byron,

I do not understand why the turbine is running at such a low speed. With steam and at this pressure, this should be in the vicinity of 30'000 rpm. The torque will stay approx. the same, but the power output will rise proportionally.

Neil,

I do not think it is sintering. They call it "Additive Manufacturing". have a look at their homepage

http://www.ecoparts.ch/                      ( switch to englisch language)

As to the full ceramic/hybrid ball bearings - both fail, but it seems to me that they fail much quicker when rigidly mounted in the test stand. I put the turbine now on rubber dampers. The turbine bearings in the existing locos hold up quite well.

Werner

Edited By Werner Jeggli on 18/08/2019 12:59:52

Hello Turbine Guy,

I think, the ECOPARTS rotor of your design is valid. but it would require different nozzle designs. I will follow up this idea later on (age permitting). At present I'll concentrate on my old design. The power generated there is sufficient for our gauge 1 locomotives. Here are the results of the last tests:

**LINK**

(I've problems with inserting the link, hope it works)

I have also a problem with my precision lost wax caster. He did also the nozzle castings at reasonable prices. He seems to be out of business. Alternative suppliers are much more expensive.

Werner

Hello Turbine Guy,

Please have a look at your inbox.

Werner

Hello Turbine Guy,

The different systems of units (imperial/metric) are really a pain in the ass !!

With a steam throughput of 0.555 oz/min (0.26 g/sec) at 50 psig (3.5 Bar) saturated steam you get a shaft output of 9.34 Watt.

My steam throughput is 0.287g/sec at 4 bar. Saturation estimated at 0.9 and shaft output of 8.7 Watt. So the results are more or less in the same ball park.

And then, how are the ball bearings doing? How much of the precious power are they eating away? My wheel side one went bust yesterday! I replaced it with a full ceramic 3x7x3mm. We will see how long it will hold.

Werner

Hello Mike,

You were right. I calibrated T2 in the kitchen in a pot of boiling Water to 99°C. Now turbine steam exit is also 99°C. T1 I calibrated with steam going to atmosphere also to 99°C. The readings should therefore be correct in the future.

Schlieren is located 350m above sea level and the weather was nice - 99"C should therefore be good enough.

Gentlemen,

Yesterday, we repeated the test. It was halfway successful. In previous tests I got better output. In addition, there is a discrepancy in the turbine pressure/temperature values. What do you make out of these data?

Mike,

Sorry, the coil OD is 85mm!

Werner

Mike,

The copper pipe is 10 x 8mm, 6 Windings, 350mm OD, height 140mm, installed in a can. Can filled with ice cubes and water prior to test.

The thermocouples are bare ended. They came with the handheld measuring instrument, *roline 307" , 2 measuring points. This was years ago.

regards Werner

Hello Mike,

I really do not feel at home in the pressure/enthalpy/entropy world. I'm trying to follow Norman Billingham's excellent series of articles in the SMEE Journal, but it's hard work and my grey cells are old and probably encrusted. If you tell me the measurements at the turbine entry can be taken at face value for further calculations - that's fine.

Yesterday, with the help of 2 friends (to also take simultaneous readings) we ran the test with 2 nozzles in action - and it was a total failure. The boiler couldn't keep up with the 2 nozzle steam demand. We will have to repeat it. With just one nozzle it should work.

To give you an idea of the hectic involved - have a look at the set-up!

and the expected data

Hello Mike,

I do not think the loss in pressure between boiler and turbine entrance is only due to friction losses in the piping. The main difference must be the more or less static steam pressure in the boiler and the reduction of pressure in the turbine inlet pipe due to its reduced cross section and therefore high speed of the medium (steam). (airplane wing effect). Pressure loss will however be compensated by an increase in entropy (the molecules move in the same direction). How to take this mathematically into account is above my capability.

Gentlemen,

Today, I test ran the turbine and with 2 nozzles 0.8mm dia, 3 Bar boiler pressure. I got 41'000 rpm, 22V, 400mA DC output. Now I need also to determine (measure) the other relevant parameters over a 5 minute period like liquid gas consumption, steam temperature, -pressure and -throughput. I would also like to measure the steam temperature prior to entering the nozzles with a thermocouple in direct contact with the steam. However, the steam rushes by very fast, hence its pressure will be substantially lower than the boiler pressure. Does this make the steam more saturated (because of the lower pressure) and how can I take this into account?

The exhaust steam will be condensed in a water cooled spiral tube and then the condensate measured.

Any suggestions ?

Hello Turbine Guy,

Your turbine parts look beautiful, are supported by theory and are also well machined. I really hope it will pan out in the end.

I just returned from a G1MRA event in Toulon/France where I ran the PRR-S2 with 5 coaches for half an hour and everybody clapped their hands. I took along my multipurpose model steam turbine project and discussed it with anybody showing their interest (quite a few).

My ambition is to create versatile steam turbine, which could be used for generating purposes using two 0.8mm nozzles, mounted either at the top or the bottom of the turbine casing for turbo generator application. By using the second slot for a reverse nozzle, working the forward blades from the wrong side (awful engineering - but it works at the price of awful efficiency) it can also be used for a direct mechanical drive.

I'm quite confident that I can reach the peak 10 Watt shaft power target and will run the corresponding tests to prove it.

Below is a bad picture of nozzle inset drawing and a Toulon picture. Behind the flower you see the PRR-S2.

Hello Turbine Guy,

Thank you for the flowers. You are right of course with your nozzle proposal, which is in line with the real world technology. The thing is, it doesn't work for my small model turbines. I'm not a watch maker, and with a 0.8mm orifice I'd have problems producing it. Then, in our locos, the space available for nice straight and smooth steam runs is limited. Thirdly (and probably most importantly), the steam leaving the nozzle will be turbulent, creating complete chaos in the turbine housing. This makes nice calculations to the third digit irrelevant! My best results so far I got with doctors injection needles 0.8mm ID and 1.2mm OD, suitably bent and silver soldered in.

In the next days, should be receiving improved sets of lost wax cast nozzle units, eliminating the need for injection needles and also new lost wax cast turbine wheels. Well - I'm hopeful.