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Flashcards in Performance Metrics Deck (9)
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1

List 5 examples of performance metrics

Polytropic efficiency
Propulsive efficiency
Overall efficiency
Specific fuel consumption
Specific thrust

2

What is the relationship between compressor efficiency and pressure ratio?

It is found that the compressor efficiency tends to decrease as the pressure ratio for which a compressor is designed increases

3

What's the definition of polytropic efficiency?

The isentropic efficiency for an elemental stage in a process such that it is constant through the whole process

4

What's the definition of propulsive efficiency?

The ratio of thrust power to the sum of thrust power and jet kinetic power

5

What do you want for high propulsive efficiency?

Jet velocity must be higher than the aircraft velocity (but not too much higher)

6

What is the efficiency of energy conversion?

A measure of how much kinetic energy is gained by the engine jet relative to the energy contained in the fuel

7

What is the definition of overall efficiency?

The ratio of the work done in overcoming drag to the energy supplied by the fuel

8

What is the definition of specific fuel consumption (SFC)?

Fuel consumption per unit thrust

9

What is the definition of specific thrust?

The thrust per unit mass of air flow