exhaust velocity
Noun
Meaning
exhaust velocity (plural exhaust velocities)
(aeronautics) The speed with which the exhaust gases leave the rocket engine.
Examples
According to Edgar Choueiri magnetoplasmadynamic thrusters have input power 100-500 kilowatts, exhaust velocity 15-60 kilometers per second, thrust 2.5-25 newtons and efficiency 40-60 percent.
Actual and effective exhaust velocity are the same in rocket engines not utilizing air.
Also, sometimes rocket engines have a separate nozzle for the turbo-pump turbine gas, and then calculating the effective exhaust velocity requires averaging the two mass flows as well as accounting for any atmospheric pressure.
Because the motion of this induced current flow is perpendicular to the magnetic field, the plasma is accelerated out into space by the Lorentz force at a high exhaust velocity (10 to 100 km/s).
A rocket with a high exhaust velocity can achieve the same impulse with less reaction mass.
Energy efficiency Plot of instantaneous propulsive efficiency (blue) and overall efficiency for a vehicle accelerating from rest (red) as percentages of the engine efficiency- note that peak vehicle efficiency occurs at about 1,6 times exhaust velocity.