10/98 engine

[racket]

LOL.................I'm not , I'm on the Mid North Coast of NSW , but my fellow collaborator Andrew is in Dandenong and has the 10/98 engine in his bike build jetandturbineowners.proboards.com/thread/34/motorcycle-project ................he also has my TV84 based turbine bike ..............you really should get in touch with him

[azwood]

Yeah dandynongs not to far from me about 50ks it would be well worth a look and talk to him.

Jun 29, 2018 15:57:54 GMT -5 racket said:

LOL.................I'm not , I'm on the Mid North Coast of NSW , but my fellow collaborator Andrew is in Dandenong and has the 10/98 engine in his bike build jetandturbineowners.proboards.com/thread/34/motorcycle-project ................he also has my TV84 based turbine bike ..............you really should get in touch with him

[racket]

Shoot me a PM and I'll pass on a phone number

[azwood]

Yeah no problem thanks

Jun 30, 2018 0:01:46 GMT -5 racket said:

Shoot me a PM and I'll pass on a phone number

[smithy1]

I spoke to Andrew just the other day..😁😁

Smithy.

[Chuks]

Hmm! Why am I buried so deep in West Africa?
Would have love to go have a look too! Lol!

[madpatty]

Hi Racket,

Did you follow 30/20/50 rule for hole areas in these sized engine also.

Can you tell how have you distributed the holes along the length of the combustor and what sized holes have you used?

Cheers.

[racket]

Hi Patty

Yep , 30/20/50% of inducer area , the "hole in the front" is 98.6mm , so 7636 sq mms of flametube hole area , give or take a few sq mms .

50% of that area ( 3818 sq mms ) in the outer side wall , 35% on the inner and 15% in the rear wall which included the evap tube bores.

Primary .....outer wall 18 X 4 mm, 36 X 3 mm , 18 X 4.8mm , inner wall 36X3.5, 36X 4mm, evaps 18X ~8mm bores, this produced a tad over 30% of inducer , but close enough.

Secondary .....outer wall 36 X 6mm . inner 36X2mm , bit under 20%

Tertiary .....outer wall 18 X 11.0 mm , 36 X 5X2 mm louvres, rear wall 18 X 4mm , 36 X 2mm , inner wall 18 louvres 4 X 1 mm , 18 X 2 mm , inner rear wall 18X6mm , 18 X 8 mm , bit over 50%

Thats all the info I have , don't have axial positioning on the wall , you might need to scale off the pics , the outer wall was ~110 mm long , the inner ~65-70mm , rear wall ~225 mm dia.

Cheers
John

[madpatty]

Aug 6, 2010 23:37:20 GMT -5 racket said:

Main structure of engine

Hi Racket.

i was looking at the shaft tunnel design.
What hole diameter you use for oil inlet and outlet?

Is outlet gravity assist only or you use a suction pump.

Also I was curious what is this small pipe(highlighted in yellow) for?



Regards.
Patty

[racket]

Hi Patty

LOL........I haven't the faintest idea what that pipe was for , better check my build notes .

OK found it , it was a compressed air line to aid lube scavenge on shutdown to prevent lube bypassing the turb end oilseal whilst conducting cooldown running of the lube pump, there was a gallery through the shaft tunnel to feed air to the turb piston ring seal area .............never used, a scavenge pump would be a better method , I was trying to get away without using one ..................I had a small 12V air comp on the teststand that was going to be used if necessary , but nothing ever came out of the metal tube so it wasn't hooked up

The lube inlet gallery was 8 mm with 1/4 BSP fitting for supply and oil pressure pickup , drain 11.5 mm , with a 15/16" UNEF threaded outlet , lube is easily expelled when running due to the leakage of air/gas past the seals with no need for a scavenge pump, at other times a large capacity scavenge pump would be required to minimise any bypassing of lube .

Cheers
John

[madpatty]

Sept 11, 2010 16:53:29 GMT -5 racket said:

Hi Richard
Yep, she'll be resurrected , just need a bit of new "tin work" and a cleanup , she was running so nice the other day , right up to 100% at 66,000rpm , at 61,000 with a comp tip speed of ~1475 ft/sec , she was putting out a 2.75 pressure ratio at 73% efficiency with a T2 of 150 deg C and a TOT of ~575 deg C .

Heres the "autopsy report " I posted on the DIY Site .......

....I've been having a real good hard look at things and it seems the flames have come out of the flametube to contact the shaft tunnel heat shield , it was hot enough to melt the ceramic blanket material inside the steel outer sheath .

Theoretically the flame can't come out of the flametube as there is a pressure drop across the FT wall and a lower static pressure inside the FT .

So far all I can put it down to is the lack of straightening vanes at the diffuser outlet , there is some straightening of flow from the cast in place vanes , but looking at burnt oil witness marks on the FT exterior it appears as though there is still considerable swirl around the FT .

Now for swirling air to travel from a large radius to a smaller radius, as it has to do from the diffuser outlet , down the back of the diffuser wall and in to the inner wall of the FT, its velocity has to increase and its static pressure will drop , exactly the reverse of the comp diffuser .

This decrease in static pressure could have been enough for the static pressure within the FT to be higher than the static pressure existing around the shaft tunnel , causing flames to exit into the space between FT and shaft tunnel , it appears as though the flames have then gone forward to contact the backside of the diffuser wall and up and over the front of the FT as there are witness marks showing where bits of metal have scraped surfaces ., also the edges of the FT wall at the failure have the rough edge outwards as well as molten metal "droplets" on the outside of the FT , all indicating an air/gas flow in the opposite direction to what it should be .

On my FM-1 engine I retro welded on "curved ears" at the FT outer edge opposite the diffuser outlet to direct air down the rear wall of the diffuser as there was some appearance of heat stress on the inner wall of the FT , the 9/94 engine had a FT with "ears" opposite the diffuser outlets and still had a "hot" inner wall , but I put it down to the FT not being very far from the diffuser wall restricting the turning of airflow at the diffuser outlets , the 10/98 has its FT displaced further rearwards due to the large scavange oil gallery on the back of the diffuser wall and I didn't feel it needed any "turning ears" ................guess I was wrong :-((

Straightening vanes as well as some sort of curved deflector required ...........................thankfully no major damage to the turbine wheel , some buildup of metal on its tips and a fairly bad rub where the blades turn from radial to axial ( in the corner) , hopefully it can be cleaned up good enough to reuse after a balance ......................compressor end all OK .

Something I just remembered .................on FM-1 when I first put her together , I felt there was a similar thing happening with flames coming back from the turbine wheel thru the ball bearings that were fed air from near the inner wall of the FT , I ended up fitting "snorkels " from the diffuser outlets to feed the shaft tunnel the highest pressure air I could , it did fix the "reflux" problem ..............mmmmm , might be whats happening now .

All food for thought :-)

Cheers
John

Hello Racket.

I was just doing a thought experiment on this theory of using a deflection system at diffuser outlet.
No doubt its working very nicely.

I have a question and that is in line with the same Swirl speed theory that you shared.

For swirling flow to go from large to small radius, it will speed up(angular momentum conservation).
So in that way should the flow speed up(thus static pressure again reduces) even after you used the diverging duct towards inner flametube as the swirling flow is again going inwards?

I think the use of straightening vanes in that inwards diverging duct is what removes the swirl and thus prevent it from speeding up?
maybe?

Thanks.
Patty

[racket]

Hi Patty

Yep , the deflector makes sure that ~50% of the air gets turned "inward" rather than just shooting straight on along the FT OD , its the radial straightening vanes that make sure that theres no swirl and consequently no static pressure drop.

LOL.......Thats my "theory" , don't know if its correct or not , but it seems to keep things working

Cheers
John

[madpatty]

Nov 6, 2020 5:13:58 GMT -5 racket said:

Hi Patty

Yep , the deflector makes sure that ~50% of the air gets turned "inward" rather than just shooting straight on along the FT OD , its the radial straightening vanes that make sure that theres no swirl and consequently no static pressure drop.

LOL.......Thats my "theory" , don't know if its correct or not , but it seems to keep things working

Cheers
John

Hi Racket.

Do you have any pictures of the air deflectors in this 10/98 engine of yours?

Regards.

[racket]

Hi Patty

I finally found some pics , I'd forgotten how I did the 10/98 ,its been >10 years , but it looks like I machined up a "ring" of 2 mm stainless , that I then cut into bits for mounting onto the back of the diffuser wall , the deflecting channels were then welded to the stainless ring pieces, a lot more involved method than I used on the 12/118 , thats progress :-)

Hope these help











Cheers
John

[racket]

Patty , some 9/94 pics










Cheers
John