Engine Power | Efficiency

Question 1

Efficiency concerns the ratio between the ___ and the ___ an engine

Answer 1

work put into, work gotten out of

Question 2

Thermal efficiency measures how much ___ energy is converted to ___ energy in the form of increased gas velocity, as a percentage

Answer 2

heat, kinetic

Question 3

Outline how piston engines vary their efficiency with power setting

Answer 3

The piston engine keeps its efficiency at almost any power setting

Question 4

Outline how turbine engines vary their efficiency with power setting

Answer 4

The engine efficiency is directly related to the percentage of power being produced.

Question 5

For turbines, the specific fuel consumption is better at ___ power settings as the engine runs ___

Answer 5

high hotter

Question 6

The turbine becomes more efficient when the gradient between the hot gas and cold environment is very ___

Answer 6

high

Question 7

The delta temperature is the gradient between the ___

Answer 7

hot gas and cold environment

Question 8

The EPR is the ___

Answer 8

engine pressure ratio

Question 9

The engine pressure is the difference between ___

Answer 9

what goes in and what comes out

Question 10

turbine fuel contains ____ BTUs per pound

Answer 10

17500

Question 11

There are ___ ft lbs per BTU

Answer 11

778

Question 12

1 HP is around ___ BTUs per hour

Answer 12

2545

Question 13

Propulsive Efficiency is a measure of how much ____ energy is converted to propulsion in terms of ___ ___

Answer 13

kinetic forward speed

Question 14

Propulsive Efficiency =

Answer 14

( TAS x 2 ) / ( TAS + Vje )

Question 15

Vje is the ____

Answer 15

velocity of the outflow of gasses from a turbine engine

Question 16

There is a maximum PE when the TAS equals ____

Answer 16

The speed of the outflow

Question 17

Mechanical efficiency is the ratio of ___ to ___ horsepower, or ___ ___ to ___ ___

Answer 17

brake, indicated, power input, power output

Question 18

Around __% mechanical efficiency can be expected from a piston

Answer 18

80

Question 19

Specific Fuel consumption is directly related to ___ and ___ efficiency, measuring ____

Answer 19

thermal, propulsive, overall efficiency

Question 20

Specific Fuel Consumption is the ___ of fuel used in ___ ____ to developed 1 ___ of thrust, or the ___ required to produce unit power for unit time.

Answer 20

weight 1 hour pound mass

Question 21

Jets are generally measured in terms of ___, whereas turbines are measured in terms of ___

Answer 21

Thrust, Power