|
|
Post by scootwhoman on Aug 31, 2011 4:48:19 GMT -5
Alright! I have finally found some folks who have some knowledge of turbine engines! The turbine engine is a superior form of internal combustion engine, as the combustion process is continuous, instead of intermittent. (Reciprocating or rotary engines are example.) However, turbines do not handle sudden changes in load very well, which has hindered their adaptation in vehicles.
Using computers, it is now possible to finely control the load on a generator, so that the power plant is able to respond smoothly. A bank of capacitors and some batteries can provide the energy for quick starts or acceleration, and absorb energy when braking.
One of the big drawbacks of turbines is the long start times most of them have, due to the high rpm's needed to allow clean ignition. The ideal way of starting a turbine is with another turbine, or with some form of compressed air to get the bigger turbine spinning.
By using a two turbines, one a smaller Auxiliary Power Unit, one of which is running whenever the car is in motion, that delay could be avoided. Holding the primary turbine at 10 percent rpm or so would enable much quicker starts, I would think.
Thoughts, anybody?
|
|
|
|
Post by Johansson on Aug 31, 2011 6:32:46 GMT -5
Many have been down that road only to realise that fuel consumption does matter for the average bloke...  The only place where I can see a gas turbine as the best choice is where the power-to-weight ratio has to be very high, i.e. aero machines. (and natural gas generators and so on, but I was thinking in vehicle terms) |
|
|
|
Post by ernie wrenn on Aug 31, 2011 7:56:18 GMT -5
Go with a APU and battery pack. I Made a idle circuit that would idle at 25% . Fuel eficant NO. Rapid accleration yea 3 to 5 seconds but it was producing voltage all the way up. Most are 400 cycles so be careful on choice 60 cycles are standard stateside.
ernie
|
|
|
|
Post by Richard OConnell on Aug 31, 2011 12:22:41 GMT -5
I'm thinking the best way you could use a turbine for "direct drive" would be to connect it to an automatic transmission with a very loose torque converter and a lot of gears... I've seen some 6-speeds in production for the general public right now, but I'm thinking like a 10speed or more. You would be able to compensate for the turbine's inability to quickly change RPMs by having a plethora of gears at your disposal.
Just my thoughts.
|
|
andrewo
New Member
Love engines especially radials
Joined: November 2011
Posts: 3
|
Post by andrewo on Mar 17, 2012 14:52:05 GMT -5
Has anyone thought of the hydraulic pump and motor possibility?
It work of the riding lawn mowers, bow thrusters on yachts and powers prop shafts in larger units.
|
|
|
|
Post by Richard OConnell on Mar 17, 2012 20:23:50 GMT -5
How much energy is lost in a configuration like that? I have had interestin using hydraulic motors/pumps but I'm not really sure of the loss.
|
|
|
|
Post by ernie wrenn on Mar 17, 2012 20:53:01 GMT -5
Paracidic loss is unbeliveable. I have tried several systems to power hyd motors. The volume needed to get a hi speed motor running is not reasonable.
They work great for low speed high torque but when you switch to high speed you loose most of the torque. Adding gear drives to convert speed back to useable torque increases the paracidic drag.
ernie
|
|
GrantB
Junior Member
Joined: February 2012
Posts: 61
|
Post by GrantB on Mar 18, 2012 0:02:37 GMT -5
I think the best part about a turbine car would be its light weight but most production cars would have a hard time taking advantage of this. I think the only way to make this feasible would be to also have some sort of way to recoup the exhaust heat as well. Don't some of the GE power station turbines get 80-90% efficiency with converting exhaust heat into steam power?
Everything will have trade offs.
Check out Jaguar's sports car prototype that uses 2 turbines to power electric motors. Really a cool setup.
|
|
|
|
Post by Richard OConnell on Mar 18, 2012 3:37:27 GMT -5
there are some decent drive turbines available on the market thet could easily fit in a car. I would start with like an Allison 250. They are a bit expensive to acquire though. I was wanting to get one for go kart, but its probably best i didn't  |
|
|
|
Post by turbochris on Mar 18, 2012 7:09:30 GMT -5
To hell with fuel efficiency. Imagine a simple single shaft turbine all electric drive whub motors. a big enough turbine to maintain a real high top speed w enough lipo batteries to get it there real quick. All brushless motors at each corner means massive programming options for handling/traction control/braking. it would haul ass. Since this would all be powered from a DC bus, a used APU w 400 cycles could just be rectified to DC.
|
|
|
|
Post by thunderbirdsarego on Jun 7, 2012 5:25:55 GMT -5
I think Chris has the best scheme. Capstone units are used in some buses in Christchurch NZ. because the alternator is direct drive on the turbine there is no gearbox. Regular guys with hobbyist budgets just have to make do. I wanted to go hydraulic but the pumps and motors are not cheap to find or run. In the end got a 25 kVA alternator and ran a VSD to 3 phase motor. It does run but misses out on the advantages of 4 hub motors. I searched for them to no avail. Even a single DC motor is too pricey. www.youtube.com/watch?v=tXRKCN-TFqw&feature=plcpIt has been done hydraulic with the same APU www.youtube.com/watch?v=ZE1HnJmUTVY&feature=plcpand www.popsci.com/diy/article/2009-06/popsci%E2%80%99s-own-jet-powered-atvI only did mine to make some noise and have fun. Still call it a green car cause it will burn vege oil (I presume) Ralph |
|
|
|
Post by pictsidhe on Jul 20, 2014 6:47:28 GMT -5
The problem is the turndown ratio. Ticking over, a turbine drinks fuel at a ridiculous rate, low throttle is also hideous. There are ways to make a turbine efficient across a broad power range, but by the time you've finished, you've got an expensive, bulky, heavy and complex engine that won't do much better than a turbodiesel for consumption. Hybrid is one solution, but you still won't get much better consumption than a diesel even if you use an optimised heat exchanger turbine. For buses they can tweak the power to fit a regular route and amount of power consumed, you'll need a far bigger margin on a car for when you want to 'test' the top speed. Chrysler tried it in the 70s/80s and despite using heat exchangers and putting a lot of effort in, the mpg was dismal. Starting it is also going to drink fuel and take a few minutes, as well as doing nasty things to life, so you don't really want to do start/stop. As for transmission, Chris has already explained the best way. If you don't care about mpg or just want to run at high throttle, it gets much more feasible: en.wikipedia.org/wiki/STP-Paxton_Turbocar |
|
cobrajet
New Member
Joined: May 2015
Posts: 8 
|
Post by cobrajet on May 28, 2015 0:12:15 GMT -5
Go with a APU and battery pack. I Made a idle circuit that would idle at 25% . Fuel eficant NO. Rapid accleration yea 3 to 5 seconds but it was producing voltage all the way up. ernie I'm seriously contemplating modifying my project car to accept turbine power. It only weighs 1820 lbs with half a tankful so I don't need a great big engine. Ernie, I'd like to know more about this idle circuit that you made. Having an engine in a car that idled at 60% as I have seen some is just not a great thing. I'm sure that you'd burn up a lot of clutches.  |
|
|
|
Post by ernie wrenn on May 28, 2015 13:57:21 GMT -5
Apu can sustain @ 40% I have went to 30% but some problems with recovery and can flame out.
|
|
|
|
Post by arnoldwalker on Aug 28, 2015 9:50:02 GMT -5
I'm thinking the best way you could use a turbine for "direct drive" would be to connect it to an automatic transmission with a very loose torque converter and a lot of gears... I've seen some 6-speeds in production for the general public right now, but I'm thinking like a 10speed or more. You would be able to compensate for the turbine's inability to quickly change RPMs by having a plethora of gears at your disposal. Just my thoughts. |
|
