Decision decisions

[racket]

Hi Guys

Got an early Christmas present today , billet ......117.5mm inducer......... 151mm exducer with extended tip to 163mm ,....... bugger, its too big for a TV94 turb wheel :-(



mounted on an old burnt out TV94 wheel from my FM-1 experiments

Cheers
John

[mitch]

That thing is massive

[enginewhisperer]

very nice!

[racket]

Heh heh , ~4 lbs/sec mass flow , just gotta find a way of spinning it to 70,000 rpm , the wheel suppose to be good for 70 psi P2 , though I'll only be wanting ~60 psi max , a 5 :1 PR seems a nice figure to aim for .

[Johansson]

Sweet!

Making an axial turbine out of a sheet of inconel is no option?

[racket]

Hi Anders

LOL, I only wish it'd be that easy , power requirement from the comp will be close to 500 hp .

I'll do some "numbers" for a lower pressure ratio and see if the TV94 could supply the power with a radical clipping of the exducer to get the mass flow through , this might be OK for a thrust engine where the lower PR isn't such a drawback to creating good thrust levels .

Heh heh , I could always use the comp as a paper weight if I can't find a solution ;-)

No news yet on the other "upgrade" wheels .

Cheers
John

[smithy1]

Hi John,

I "may" have a suitable "axial" turbine wheel for you....it came out of a Noelle Starter, used to start the old Mirage 2000 aircraft and have ~180shp I believe....alternately how would a 1st or 2nd stage RR250-C20B gas producer turbine wheel go...?
It's sitting on a shelf in my mancave, I'll get it out this evening and do a few measurements for you..!

[racket]

Hi Smithy

I've tried doing the numbers for both the first and second stage C20 wheels but both are a bit short in flow area , also their diameter is getting too close to the comps diameter leading to excessively high turb tip speeds , I'm looking at comp tip speeds up ~1,900 ft/sec , the turb tips will probably be flying off at any reasonable temperature, ............its a bummer because those second stage wheels are such beautiful bits of gear :-(

As this comp wheel is made for use on a Cummins/Holset HX82 turb wheel , probably in a tractor pulling scenario , it might be possible to use the TV94 turb wheel if I can "fiddle the numbers", ...........I see it as a thrust engine compressor wheel rather than a shaft horsepower wheel due to its ~56 Trim configuration where its mass flow capacity takes precedence over Pressure Ratio , theres no reason why it couldn't flow up to ~4.5 lbs/sec with the right turb stage , potential thrust >200 lbs dry...... 300 lbs with afterburner a possibility ??

Theres always the option of splitting the airflow from the comp , some going to the usual combustor and a turbine wheel with full expansion through it, whilst the bleed air/gases going to a separate combustor and jetnozzle/freepower ................LOL, decisions decisions :-(

On a separate note , I think I've found the "perfect" comp for the standard TV94 turb wheel , got 2 comps wheels on order which should be here before Christmas , billet again but with a "modest" 106.5mm inducer and a 152 mm exducer with extended tip to 157mm , 3-3.3 lbs/sec mass flow which will marry nicely with the C20 4th stage freepower wheel in the bike for >200 hp output...............its sorta like a "modern" GT6041 comp wheel , 16 blades vs 12 , 157mm exducer vs 141mm , billet vs cast , ~47 Trim vs 56 Trim ...........I've been searching for a wheel like this for years :-)

This wheel mounted up with the standard TV94 turb wheel could be spun to our "normal" 70,000 rpm without turb wheel structural problems , but the extra ~15mm of "tip" on the comp compared to the TV94 comp will give us the 5:1 Pressure Ratio without any worries , the extra PR will not mean a lot of changes from the standard TV94 designed engine , the extra 0.5- 0.8 lbs/sec will be "absorbed??" by the PR .

I've been doing a fair bit of the preliminary comp diffuser design work , big vaneless space outboard of the wheel to get those supersonic air velocities down to ~M 0.9 before the diffuser vane leading edge is encountered , then a fairly long shallow divergent passageway where the flow will be at a modest speed by the time it "turns the corner" , a 12 inch case like the FM-1 engine should do the job..............LOL, I've used up a fair number of sheets of cardboard drawing up the numerous variations until I feel I'm getting close .

Looks like I'll be busy in 2015.

Cheers
John

[smithy1]

Yeah..the Noelle Starter wheel will be far too small...pity really because it's a beautiful thing to behold..!

[racket]

Hi Smithy

Was that the wheel I did some numbers for to see if it'd match that low Trim comp wheel I had ??

Yep , a beautiful turb wheel :-)

On the BIG thrust engine design , it looks like I might just squeeze a flow of ~3.65 lbs/sec through the TV94 turb wheel at a 3.5 PR if I cut off a heap of exducer to open her up , relying more on "impulse" energy going in rather than "reaction" energy going out to get the required power,which won't be all that high ( ~300 hp) due to the low pressure ration and high comp efficiency , the inducer velocity triangle matches beautifully with the inducer tips ~23 degree angle at the modest 60,000 rpm required , outflow velocity from the turb will be rather high at ~1500 ft/sec ................a similar setup to my TV84

Hows the new afterburner coming along ??

Cheers
John

[smithy1]

A/B pipe is still at the welders...  It's been sitting in their shop for over a month now....frustrating  Everything else is ready to go....looks like I'll have to wait till after xmas before I can continue..! Such is life..! 

I've used Andy M's info and drawings to base mine on so it should be ok... 

Will be interesting to see what numbers you get from your new setup..

[racket]

Hi Smithy

Thats a bummer about the welding ..............yep , after Christmas .

The BIG comp still looks like a >200 lbs thrust engine , 300 with A/B.............my heads hurting from all this design stuff :-(

Cheers
John

[smithy1]

That's well over the GT6041 specs, I'm not surprised at those numbers considering the amount of air it is capable of moving..!

[racket]

Hi Smithy

Yep , its a big hole in the front :-)

Cheers
Jhn

[Salvatore]

Hello Jhon
Merry Christmas and Happy New Year,
this new project can be adapted to my project 180 pounds of thrust?
and where you bought the Billet?
thank you
savior