What are the two different exhaust nozzle designs used with the turbofan engine?

Two different exhaust nozzle designs are used with turbofan engines. The air leaving the fan can be ducted overboard by a separate fan nozzle [Figure 1-43], or it can be ducted along the outer case of the basic engine to be discharged through the mixed nozzle (core and fan exhaust together).

What is chevron nozzle?

Chevron is a triangular tooth pattern on the circumference edge of exhaust nozzles, are being implement on modern jet engine nozzles that help to reduce noise from the resulting jet. Chevrons are used to reduce the acoustic level at the exhaust.

What is Chevron nacelle?

Chevrons are the sawtooth pattern seen on the trailing edges of some jet engine nozzles. As hot air from the engine core mixes with cooler air blowing through the engine fan, the shaped edges serve to smooth the mixing, which reduces turbulence that creates noise. It sports chevrons on the nacelles, or fan housings.

What is the purpose of Chevron in an aircraft?

To combat the sound of jet-blast from the rear of the engine, Boeing, General Electric, and NASA developed serrated edges called chevrons for the back of the nacelle and the engine exhaust nozzle. The chevrons reduce jet blast noise by controlling the way the air mixes after passing through and around the engine.

When the convergent exhaust nozzle is choked What does it mean?

When flow is choked, the Mach number no longer increases and is capped at M = 1. In the case of a converging nozzle, the exit of the nozzle corresponds to the nozzle throat (as seen in Figure 1); therefore, the Mach number right at the exit does not exceed 1, i.e., the flow never goes supersonic.

Why are exhaust nozzle designs different?

As shown above, nozzles come in a variety of shapes and sizes depending on the mission of the aircraft. Rocket engines also use nozzles to accelerate hot exhaust to produce thrust. Rocket engines usually have a fixed geometry CD nozzle with a much larger divergent section than is required for a gas turbine.

What is nacelles aircraft engine?

Nacelles are aerodynamic housings distinct from the fuselage that surround exterior components on an aircraft. Nacelles most commonly protect instruments and equipment located along an aircraft’s wingspan, such as engines, fuel tanks, or weapons.

What is the condition at throat in CD nozzle?

In a CD nozzle, the hot exhaust leaves the combustion chamber and converges down to the minimum area, or throat, of the nozzle. The throat size is chosen to choke the flow and set the mass flow rate through the system. The flow in the throat is sonic which means the Mach number is equal to one in the throat.

What is a nozzle throat?

[′näz·əl ‚thrōt] (design engineering) The portion of a nozzle with the smallest cross section.