HPST 2020 Jet Engine

[racket]

Hi Andy

Yes , that T2 is very high at 140 deg C , a 131 C deg rise , this equates to an efficiency of ~61% , ........... the engine has to be running severely towards the surge or choke lines to produce that sort of outcome :-(

You'll need to get some thrust numbers to indicate which it might be .

At 430 C theres plenty of scope to add backpressure on the engine :-)

Love the video :-)

We might need to revisit your diffuser , I've been looking at your pics and the vanes might be a "problem" , you have built a very "compact" diffuser

Cheers
John

[monty]

Andy,

Love your work! When I was working on my diffuser, I tried a similar configuration to yours. I used CFD to evaluate my designs. I'm not suggesting that CFD is very accurate without experimental results, but that configuration always had a significant separation on the suction side of the vane. The large expansion immediately following the normal shock always caused separation. Trying to turn the flow, while in an adverse pressure gradient aft of a normal shock with a large expansion angle was just too much to ask. You might consider splitter vanes, in both the diffuser and the wheel. The published numbers I have seen on the no splitter wheels with more vanes indicate they are better at large flow #s and low pressure ratio. I'm not familiar with your cycle design, so I don't know how much that will effect T2, but thought I would throw it out there.

Monty

[ripp]

Hi Andy,

I am glad that you like the electric arc lighter!

I think even after the diffuser thing is settled, you're going to need a bigger compressor wheel.

the 430 C egt are very low,and your turbine wheel is huge.

a compressor wheel with an inlet of 98mm could improve things.

Ralph

[jetric]

Hi Ralf,
There is no thrust nozzle fitted to this engine yet, once a correct size thrust nozzle is fitted then the engine will be in theary under load so the EGT will increase.
The compressor wheel that was fitted to the engine that the turbine wheel was originally from (BMW/RR T312) had a much smaller inducer as it was a high pressure ratio compressor made from titanium and was capable of producing a P2 pressure of 60psi at around 80,000rpm,

Richard S.

Nov 28, 2022 3:37:14 GMT -5 ripp said:

Hi Andy,

I am glad that you like the electric arc lighter!

I think even after the diffuser thing is settled, you're going to need a bigger compressor wheel.

the 430 C egt are very low,and your turbine wheel is huge.

a compressor wheel with an inlet of 98mm could improve things.

Ralph

[praendy2203]

[praendy2203]

Hi,

here is a short video from yesterdays testrun.

All in all, its not bad.

The engine starts better than before and runs a bit cooler.

I dont know, how they put a 80mm or 85mm compressor wheel in a housing with 120mm diameter and getting 25 Kg thrust.

My compressor wheel is a 95/142mm extended tip from a Mitsubishi TD 13 turbo.
The 142mm tip, I grinded down to 136mm, to fit it in the diffuser.
Its a 8+8 wheel.

I tried 3 different wheels so far, but never changed the diffuser.
First time I used 12 wedges, but last year I changed to 15 wedges because of the new 8+8 wheel.

Will see, how to fix that front part.
I think a "crossover" or "fishtail" diffuser could work in the 200mm housing, but both is difficult to machine.

Next test with nozzle and then we will see.

Danke Ralph👍

Cheers Andy

[racket]

Hi Andy

Thats a substantial amount of thrust for no jetnozzle :-)

Assuming some "normal" flows through your comp inducer we can recon on ~1.6 lbs/sec at your 1.4 Bar P2 , this would equate to an "exhaust" velocity of ~735 ft/sec to get your 38 lbs of thrust at a very low temp of only ~450 C , you've got a ~300 C degree allowance for some backpressure , thats a lot of energy for making thrust with a jet nozzle

Yep , I agree , next test with jet nozzle at similar 1.4 Bar P2 for comparison .

Have you checked your T2 thermometer in boiling water to check accuracy ?? ,...............I get the feeling that your T2 vs TOT aren't "aligning", normally with such poor comp efficiency your TOTs would be higher .

Cheers
John

[ripp]

Hi Richard S.

my point of view

we have to put things into perspective a little

The BMW/RR T212 is an APU designed to start a jet engine with shaft power www.technologie-entwicklung.de/Gasturbines/KHD_T312/khd_t312.html

it consists of 2 areas, a) power turbine, b) gas generator

the power turbine was calculated to deliver around 140-150 hp. Residual thrust is not desired!

the gas generator provides a specific amount of hot gas at a specific pressure (60 psi) so that the power turbine can reach its target.

andy is trying to develop a jet engine with this power turbine (thanks Andy for that)

I also see the first improvement in that andy made the NGV with a new angle (30°?).

I am following this development with excitement.

Cheers Ralph

[praendy2203]

[praendy2203]

Hi,

this is a picture from Thomas Kamps book.

It shows the pressure/temperature curve at 20°C ambient and 75% efficiency.

When I check my datas, the engine runs absolutely in this field.

John sent me a data sheet from his former engine and the 140°C T2 was reached at 2 Bar.

There is a big difference.

I am also not able, to find a compressor map from my TD 13M wheel.
Maybe it would give some datas.

Wheather is not good for testing, so I do not much😊

Andy

[jetric]

Hi Ralph,

The BMW/RR T312 is a single shaft engine with a two stage turbine, it is not a two shaft engine with a power turbine, because it is a single shaft engine the power required to power the compressor and have an additional 150shp is shared between the two stages of the turbine.
I didn't know that Andy was using the second stage turbine wheel,
Also I was the first person in the UK to get a privately owned BMW/RR T312 engine running outside of the airframe, I also developed a successful throttle system for this engine.

Richard S.

quote author="ripp" source="/post/33867/thread" timestamp="1669705749"]Hi Richard S.

my point of view

we have to put things into perspective a little

The BMW/RR T212 is an APU designed to start a jet engine with shaft power www.technologie-entwicklung.de/Gasturbines/KHD_T312/khd_t312.html

it consists of 2 areas, a) power turbine, b) gas generator

the power turbine was calculated to deliver around 140-150 hp. Residual thrust is not desired!

the gas generator provides a specific amount of hot gas at a specific pressure (60 psi) so that the power turbine can reach its target.

andy is trying to develop a jet engine with this power turbine (thanks Andy for that)

I also see the first improvement in that andy made the NGV with a new angle (30°?).

I am following this development with excitement.

Cheers Ralph[/quote]

[racket]

Hi Andy

Sorry , but your "measured??" T2 temps are way too high :-(

Thomas' graph has a T1 of 293K whereas your OAT of 282 K makes a difference to the actual temp rise , 2.4 PR at 75% from 293K produces a temp rise through the comp of 111 C degs , so a T2 131 C , but in your case with a OAT of 9 deg C - 282K at 75% effic , the temp rise would only be 107 C degs and a T2 of 116 C , this is why I feel you need to check your T2 thermometer ...............years ago I tried measuring T2 on my TV84 engine and could never get an accurate reading , strange things were going on , I put it down to "static electricity" from the high speed airflow , even with my current engine I've got a number of T2 sensors to try and verify the temp .

The fact that you are running such low TOTs makes me feel your T2 thermo isn't reading correctly .

I think you'll be pleasantly surprised by the thrust increase when you fit the nozzle , the increase in turb temps will probably reduce your mass flow a tad and bring it back into a more efficient region of the map , currently your RPM /tip speed of the comp is a little "high" for the P2 being produced , which makes me feel you are flowing a tad to the choke side of the "map" .

Talking of maps .............LOL, if you find one please share it :-)

I'll be looking forward to your next test results, hope it goes off smoothly .

Cheers
John

[ripp]

Hi Richard S.

oops! " single shaft engine ", I've overlooked

thanks Richard S.

Cheers Ralph

[monty]

Andy,

What ECU are you using?

Monty

[praendy2203]

Hi Monty

I dont use an ecu.

All is managed with my 27 year old JR X3810 RC transmitter.

Have a wooden box with 2 pumps, one for the engine and one for the afterburner, rc receiver, 2 ESC and space for the batteries.

Andy