Thrusters Flashcards
Describe the terms energy consumption and propellant mass consumption of a thrustor.
How they depend on the exhaust speed?
Energy Consumption: Energy consumption is the amount of energy required to operate a thrustor. This is typically measured in terms of kilowatts (kW) and is typically determined by the amount of fuel burned. As exhaust velocity increases, Energy consumption also increases.
Propellant Mass Consumption: Propellant mass consumption is the amount of propellant used by a thrustor in order to generate a particular amount of thrust. This is typically measured in terms of kilograms (kg) and is determined by the total weight of the fuel burned. As exhaust velocity increases, propellent mass decreases.
Explain the term specific impulse. Why it is important characteristic for a thruster.
what units?
Specific impulse (usually abbreviated Isp) is a measure of the efficiency of a rocket engine.
It is defined as the ratio of the thrust produced divided by the rate of propellant usage
It is an important characteristic for a thruster because it is an indicator of how much thrust is generated per unit of propellant used. The higher the specific impulse, the more efficient the engine is
The units for specific impulse are typically seconds or newtons per kilogram.
Describe design of a cold gas thruster
Engines based on releasing a gas stored under pressure in a reservoir through a nozzle
-Storage
-Filter: remove particulates that could clog or damage downstream components
-Pressure Regulator: allows storage at pressure higher
than maximum pressure of
downstream components. Constant pressure operation
-Valve: On-Off control
-Catalyst: Used for decomposition-based propellant.
Describe design of Field-emission electric propulsion (FEEP) thruster
They use a combination of electric and magnetic fields to accelerate ions, creating thrust.
The design of a FEEP thruster typically includes
a cathode - electron emitter
an anode - a plate which attracts cathodes
a chamber filled with propellant gas - ionized by the cathodes reaching anode creating ions
a magnetic field and electric field work together to accelerate the ions, creating thrust.
Describe design and operation of the Electrostatic (gridded ion) thruster
Colloid thruster: electrostatic acceleration of charged liquid droplets.
It works by accelerating ions using electrostatic fields, typically generated by grids of electrodes, to produce thrust. The ions are ionized from a neutral gas or liquid propellant, and accelerated to high velocities.
Isp ~ 10^3 – 10^4 s, ve ~ 100 km/s,
