gasturbine lawnmower now ready

[imperial]

1st test with our gasturbine lawnmower.
Next step is to install the afterburner
Than finish the sheet metal and paint.


www.youtube.com/watch?v=4SL_bCI9SvQ

[Johansson]

Really cool project! The driver won´t exactly freeze his butt off while driving it in cold weather with that seat position... ;D

[racket]

Mmmmmm..........I can smell roasted nuts from here ;-))

Whats the turbine engine

Nice A/B

Cheers
John

[imperial]

There is a cover over the Afterburner.
this is a link of a pic of it 94.100.118.81/1159500001-1159550000/1159530001-1159530100/1159530096_6_ZKmB.jpeg
We had the turbine running vor 10 minutes and the afterburner was HOT
But the cover on witch the seat is mounted was no more than a bit warm.
Must see what happens when we use the afterburner, Maby a bit extra isolation is needed.

The turbine is a east german unit from a genarator with a output of 160 KW
Fuel consuption is a gallon in 5 minutes


Remco

[racket]

Hi Remco

Ah, thats why the engine is a familiar looking one .

May I suggest you extend the A/B cover right to the end of the A/B otherwise the radiant heat will burn the back of the seat , also if the cover goes just past the end of the A/B the exhaust will tend to draw cold air with it keeping a flow of cooling air between A/B and cover keeping things cooler than they will be at present .

Can't wait to see a video of the A/B in operation , nice build :-)

Cheers
John

[imperial]

Is there a way to get some trust out of this engine.

Lawnmower is in the painshop now, We are invited to a show next weekend.

[racket]

Hi Remco

Aren't you getting any thrust at the moment ??

As it was a shaft power engine , there often isn't much energy left in the gases after they pass through the turbine wheel .

With engines that normally produce shaft power, its necessary to remove the freepower turbine stage if you want to run the engine to produce thrust .

Is your engine equiped with 2 shafts/turbine wheels ??

Cheers
John

[imperial]

Hello John
on page 4 of this pdf file is a drawing of the turbine .
www.fh-schmalkalden.de/schmalkaldenmedia/Downloads/maschinenbau/pietzsch/Gasturbine.pdf


Regards
Remco

[racket]

Hi Remco

You'll have some difficulties getting this single shaft engine to perform well as a thrust engine :-(

Scaling off the drawing, it appears as though the turbine wheel is ~20% bigger in diameter than the compressor wheel, this makes the turbine wheel "too powerful" to drive the compressor unless there is a shaft load on the engine (generator load) .

What will happen is , the engines governor will cut back the fuel once max rpm are reached , the turbine inlet temperatures will be low because of the "reduced" load on the engine , but because the engine is designed to reduce all pressures to ambiant as the gases pass through the turbine stage , there is a mismatch of components .

Normally in a thrust engine the turbine wheel diameter is ~90% of the compressor diameter , my engines run a 129mm radial inflow turb wheel powering a 141mm radial comp wheel , this produces a more balanced matching of power requirements vs power production , the smaller diameter of the turbine wheel also reduces the pressure drop through the wheel , and if combined with a suitable NGV stage that isn't running choked will leave plenty of pressure downstream of the turbine wheel for making thrust , your NGV will have been designed to run in a choked condition to produce sonic velocity gases to power that large diameter turb wheel .

You will get some thrust from the engine once the afterburner is alight , but very little thrust without the A/B alight .

You will probably be running exhaust temperatures ( TOTs) of ~3- 400 deg C at present due to that over powerful turbine wheel extracting all the energy from the gases , but once the A/B is alight the TOT will rise due to a drop in pressure ratio across the turbine wheel .

So fire up the A/B and enjoy the change in thrust level :-)

Cheers
John

[imperial]

Hi John

Thanks for the explanation
I still have a lot to learn about gasturbine's

Will post some pics after paint
Thanks
Remco

[racket]

Hi Remco

How did you determine the afterburner dimensions , its nozzle size etc ??

Cheers
John

[imperial]

Hello John
The afterburner came with the engine. It was a DIY project from a other guy.
He had 3 of these engine's mounted on the back of his truck.
There are 3 redneck style nozzles , Just a pipe with the end hamerd flat.
one is on 1/3 th of the afterburner and 2 almost at the end.
The pipes are 3/8 inch inner diameter.
How manny gallons a minute should I pump in to them.
I'ts manly for show so 50 + ft flames would be nice.
Here is a pic of my other hobby , doing burnouts with my thunderbird with a small flame trower instaled


Thanks
Remco

[racket]

Hi Remco

One of your earlier emails said the engine was capable of ~160Kw so mass flow of air would be up ~3 lbs/sec mark as a minimum , or 180lbs/min , so your current fuel burn rate of 1 gallon every 5minutes - 12 GPH is very low and accounts for your low exhaust temps ,....... under full power conditions it'd be expected that fuel burn rates would be at least twice that .

If you only want to make flames rather than thrust then you'll be needing to feed ~2 gallons per minute to the A/B

Cheers
John

[tobbe65]

Why not use the engine to which it was designed for. If the gearbox on the engine is OK and you are able to link it to the driving wheels, you'll get a lawnmower that is something unbelievable. You can still use the A / B to increase the cool factor.With so much power and so little weight, it will be scary driving.
With plenty of crazy people who volunteer and without hesitation, would love to do a top speed test. If I had not had children I would have done it.

;D GOD SPEED Tobbe.

PS my written enelska is pretty poor so I use google translation software so please excuse the sometimes strange language. DS

[imperial]

We just had our first show.
The organisation did not want us to start the lawnmower indoors.