When I was a kid, my parents took me to the 1964 World’s Fair in Queens, N.Y. An avowed motorhead, even at the age of 11, I mainly was interested in the turbine-powered “Typhoon” automobile that Chrysler demonstrated there. The company had built 50 or so prototypes, starting in the late ’50s, with hopes of eventually putting them on the market (visit www.turbinecar.com).
But there were problems: The cars were sluggish off the line, they were not fuel-efficient, and they sounded like vacuum cleaners at a time when the rumble of an American V8 was music. (Actually, I don’t think that time ever went away.) But I was most surprised to learn that the main reason the project was scrapped in 1966 was that emissions of NOx were very high – I didn’t think they cared about that sort of thing back then.
Fast-whirr to now. A company called Turbine Truck (TT) Engines has developed a turbine engine that it says has solved earlier concerns. “Earlier turbines worked on what’s called the Brayton cycle,” explains Michael Rouse, chief executive officer of the DeLand, Fla.-based company. “They were high-pressure units that burned far more fuel than a piston engine.
“Our engine uses a lower-pressure pulse-detonation system, which sends shock waves to a paddlewheel-type turbine wheel,” Rouse says. Lower pressure, he says, creates far less NOx. Moreover, while earlier turbines constantly blew air through a conventional vane-type turbine, pulse detonation – which uses two combustion chambers that fire alternately – runs more efficiently because it’s not “on” all the time. “We expect fuel economy to be at as good as or better than in a piston engine,” Rouse says.
When detonation, accomplished by means of an igniter, occurs in one combustion chamber, the backpressure from that “explosion” shuts down fuel flow to that chamber and redirects fuel to the other chamber, and the cycle continues. While there’s no crankshaft, power provided at the turbine shaft can be transmitted, either mechanically or electrically, to the transmission.
The new design is said to spool up very quickly, addressing the response issue, but Rouse says there are other advantages, including: very few moving parts to wear; an air cooling system, which eliminates water pumps, hoses, etc.; no valves; light weight; and multifuel capability. “It will run on diesel, gasoline, methanol, ethanol
