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Question 1

What are the most significant sources of noise from the engine?

Answer 1

The most significant sources of noise from the engine originate from the compressor, the turbine, and the exhaust.

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Question 2

Which component of the engine is affected to a larger degree by a reduction in velocity?

Answer 2

Exhaust noise is affected to a larger degree than either compressor or turbine noise by a reduction in velocity.

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Question 3

What causes a shearing action in the exhaust noise?

Answer 3

The relative speed difference between the exhaust jet and the atmosphere into which it is thrusting causes a shearing action.

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Question 4

What does Figure 18.6 show in relation to sound levels?

Answer 4

Figure 18.6 shows relative sound levels from various sources, with aircraft engines being among the highest.

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Question 5

What is the principal agent contributing to an aircraft’s overall noise signature?

Answer 5

The principal agent contributing to an aircraft’s overall noise signature is the engine.

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