running turbine directly to crank 3

[SMOKEY44211]

In doing some research I ran across some info relating to the use of a turbine(s) linked directly to the crankshaft. Application was the Wright Cyclone 3350TC radial aircraft engine. Three exhaust driven turbines were mechanically linked to the crank. Without this feature the engine was rated at 2,700 take off HP. amd BSFC was .45lbs/hphr. Turbines in place boosted power to 3,500hp (3,700 in Navy applications) and BSFC was reduced to .35lbs/hphr. Also there was a patent issued in 1959 for a turbine (looks like the turbine side of a turbocharger) geared to the flywheel on a diesel engine application. My question is anyone aware of any attempt to adapt this concept to a land or sea based engine? It would appear to be a logical addition to gain power,fuel economy, and be rid of the lag normally associated with turbos. Any thoughts?------Phil

 

[DouginJapan]

Hello microhenry.

Good idea. I share your thoughts.

This is how Catapillar does turbocompounding. They are also exploring electro-turbo generation.

http://www.westwardscania.com/truck...work.asp?ComponentID=43343&SourcePageID=56704

My engine has two much potential to just go just with the generator feeding a flywheel motor however. I am talking about recovering from 35 to 50Hp. A electric motor in that catagory is large, heavy, high voltage, with expensive heavy controller and probably if the motor is anything like some of the hybrid cars it will be high voltage and in need of a buffer battery. I explored that road already.

Lovely concept but beyond the weight/performance of the long distance flier. Short trips in a motor glider are being done now with hybrid and all electrics.

My n/a 300 hp engine has one low rpm high torque turbine connected to a gearbox with two outputs. One output uses through a small carbon fiber shaft does something like you suggested for controlling the boost pressure (compressor rpms) by clamping the field on the attached generator. This energy can be sent to the alternator/starter motor that resides where the flywheel was, thus technically making the engine a hybrid in this flip mode. The other shaft sends the rest of the torque through a step down set of gears to a foward running electric clutch and cogged belt pully to the drive shaft at slightly higher rpms. The belt absorbs slight torque variations that would normally destroy gears.
If you think about it the concept is the same as Catapiller but I am going about it in a different manner,
with the generator thrown into the mix.

I am still in the testing phase but what appears to happen at some power settings is that the additional torque added to the engine power makes the engine speed up to try and match the turbo compound output rpms. If the rpm overage is set a the right parameter the engine never catches up but the increased rpms indicate an increase in performance.
The turbine must be bogging down very slightly but still we are talking about small efficiency losses for a large gains in BSFC.

The real test is to get the engine off the dyno installed in the plane and flying. Some parameter will change no
doubt. This depends how high and fast I fly, the air density, or in short how much boost I want to give the engine. More boost more fuel and more Hp. Also more turbo power output. Magically the efficiency curves show the excess energy (after boost) is greater the higher the rpm. Before we get to excited we have to remember the DRAG on the airplane also increases.

Efficiency sweet spots differ from plane to plane. Since I am running 95% pure ethanol, my long distance record attempt will be at 130 to 140 mph using a high compression three rotor wankel engine with a slight boost to 'normalize' the engine up the 8,000 ft density altitude I will fly at. The engine will be at 40 to 50% rated output and the turbo compound system will be designed to operate in that narrow range. 80% or the remaining energy will go to the compound. At these setting I could see from 10 to 20% increase in BSFC.

For aircraft operation the engine rpm can be controlled by changing the propellar load (called pitch) . Thus the plane can fly faster at the same fuel burn rate or remain at the same speed and extend range.

I am now searching for ways to reduce the size of the gear box , and sourcing gear manufacturers.

Have a great new year.

Doug

 

[microhenry]

"Warpspeed (Automotive) Dec 12, 2003
Another engine that uses a crank coupled exhaust turbine is the Napier Deltic. These amazing engines are hard at work all over the world in all sorts of applications."

Check out the Napier Nomad, 0.345 lb/ehp/hr.

http://www.home.aone.net.au/shack_one/nomad.htm

 

[Warpspeed]

That Nomad engined was certainly an incredible piece of engineering to be sure, but by all accounts it was a real dog to get started. Cost and complexity were probably its undoing.

Further development of the gas turbine really put it out of business.

The Deltic engine is still in marine use, the Australian navy have many, and they are used in locomotives.