Nozzles' Characteristics Flashcards
What nozzle is usually used?
a convergent-divergent nozzle due to the high (supersonic) speeds
What happens when sonic flow is in the throat?
chocked flow
flow rate will not increase if back pressure decreases
What happens when supersonic and subsonic flow are in divergent?
shock waves in divergent,
back pressure = exit pressure
What are ablative walls?
internal walls that are covered with a material that is continuously vaporised
What is dump cooling?
when a propellant , usually hydrogen, is passed around the chamber and dumped
What is regenerative cooling?
liquid rockets use fuel to cool the chamber via a cooling jacket
What is curtain cooling?
propellant injection is arranged so the temperature of the gases is cooler at the walls
What is film cooling?
surfaces are wetted with liquid propellant which cools as it evaporates
What is film cooling?
surfaces are wetted with liquid propellant which cools as it evaporates
How is the acoustic load generated?
by the combustion process and the high-speed flow in the nozzle jet
What is a convergent/divergent nozzle needed to do?
to realise supersonic speed at the exit
What does gravity loss refer to?
the reduction in volume resulting from the inclusion of gravity
What is multistaging?
a means to improve the performance of rockets by getting rid of the dead weight of empty tanks and structures
