Thrust Augmentation Flashcards
(14 cards)
Density of hot air and high altitudes is
Less dense
Density at sea lvl and cooler air
More dense
Low density has what effect on thrust
Produces less thrust
What do High bypass turbo fans do
Develop enough thrust at critical times eg take off = thrust augmentation
What are the dis to a bigger engine
More weight
It’s frontal area
Overall fuel consumption
Basic formula for engine momentum thrust is
Thrust = mass airflow rate × (Velocity out - Velocity in)
How can thrust be increased
Increasing mass airflow
Increasing exit velocity of the exhaust gases
How can mass airflow be increased
Injecting water into the compressor
Injecting water into the combustion gas flow
Or combination of the two
Name the process:
Spray of water is injected into the compressor, water droplets will evaporate, heat is transferred to the water from warm airflow,
Airflow cools density increases = improving mass airflow
Compressor water injection
Name the process:
Water cools the gasses, additional fuel to be burned without exceeding the engines temperature limits
Cooled airflow increases in density mass flow increases
Combustion system water injection
How do you increase exhaust gas velocity
Afterburning
Noise suppression where is noise most prominent
Fan/compressor
Jet pipe/exhaust
How can fan noise be reduced
acoustic liners
Extended lower lip (scarfed intake) reflects noise upwards
Exhaust noise suppression is done by
Lobe type exhaust duct - mixes air with gas
Serrations - achieve the same effect
