When the turbine engine is operating, the first- stage turbine rotates the centrifugal compressorunpeller to draw in air and compress it. The compressed air is heated as it passes through thehigh-pressure side of the regenerators, and then it enters a combustion chamber (burner) intowhich fuel is injected and ignited. The burning fuel raises the temperature of the gases (a mixtureof combustion products and air) and increases their energy level. These hot gases pass throughthe first-stage turbine driving the compressor and then through the second- stage turbine (powerturbine) which drives the car. The gases leaving the power turbine pass through the low-pressureside of the regenerators, giving up heat to the regenerator honeycomb, and flow out the exhaustducts.
With two small regenerators, the engine is compact and has balanced temperature gradients onboth sides. Intake air from the compressor is split into two paths, which pass through theregenerators and come together again at the burner. The hot gases from the burner, after goingthrough the two turbine stages, also are split into two paths to flow through the two regeneratorsand then out through the exhaust ducts.
The compressor and first-stage turbine, along with the burner and regenerator, are called the "gasgenerator" section of the engine since these components produce the hot gases that power theengine.
'Me two turbine wheels are not interconnected mechanically, and thus one may rotate while theother is stationary. The first-stage turbine always rotates while the engine is operating, its speedvarying from 18-22, 000 rpm at idle up to about 44, 600 rpm at rated power. 'Me second-stageturbine, being connected directly to the car's drive train, rotates only while the car is in motion. Its speed ranges from zero at standstill to a maximum of about 45, 700 rpm.
Since the power turbine is rotated by hot gases and is not mechanically connected to the gasgenerator rotor, the power turbine stops whenever the car stops, and the gas generator continuesidling. Thus the engine will not stall under overload.
Nozzles
Both turbine wheels are axial-flow type (like windmills) and the hot gases are directed into eachturbine wheel blade row at an angle by nozzles. A nozzle assembly made of a ring of fixedairfoil-shaped vanes directs gas flow to the first-stage turbine blades, and a ring of variable vanesdirects gas flow to the second stage turbine.
The variable nozzle system for the power turbine is one of the outstanding features of the Chryslerengine, permitting it to deliver high performance over the full speed range without exceeding safetemperature limits. At starting or idle, the nozzles are open, with the vanes directing gas flow inan essentially axial direction; as the accelerator pedal is depressed, the vanes turn to direct thegases in the same direction as the rotation of the power turbine. The nozzle angle varies withpedal position to provide optimum cycle conditions. In this manner, the direction of gas flow isalways at an optimum angle for maximum performance and efficiency without reducing enginelife.
