Search results
Results from the WOW.Com Content Network
If the rocket or aircraft is moving at about a constant speed, then distance divided by time is just speed, so power is thrust times speed: [9] = This formula looks very surprising, but it is correct: the propulsive power (or power available [10]) of a jet engine increases with its speed. If the speed is zero, then the propulsive power is zero.
This force, called thrust, is the sum of the momentum difference between entry and exit and any unbalanced pressure force between entry and exit, as explained in "Thrust calculation". As an example, an early turbojet, the Bristol Olympus Mk. 101, had a momentum thrust of 9300 lb. and a pressure thrust of 1800 lb. giving a total of 11,100 lb. [1 ...
The direction of the drag force is parallel to the relative wind. Typically, the wind turbine parts are moving, altering the flow around the part. An example of relative wind is the wind one would feel cycling on a calm day. To extract power, the turbine part must move in the direction of the net force.
The power extracted from the fluid by a rotor in the scenario described above is some fraction of this power expression. We will call the fraction the power co-efficient, C p {\displaystyle C_{p}} . Thus the power extracted, P o w e r e x t {\displaystyle \mathrm {Power} _{ext}} is given by the following expression:
TSFC or SFC for thrust engines (e.g. turbojets, turbofans, ramjets, rockets, etc.) is the mass of fuel needed to provide the net thrust for a given period e.g. lb/(h·lbf) (pounds of fuel per hour-pound of thrust) or g/(s·kN) (grams of fuel per second-kilonewton). Mass of fuel is used, rather than volume (gallons or litres) for the fuel ...
Energy–maneuverability theory is a model of aircraft performance. It was developed by Col. John Boyd, a fighter pilot, and Thomas P. Christie, a mathematician with the United States Air Force, [1] and is useful in describing an aircraft's performance as the total of kinetic and potential energies or aircraft specific energy.
For example, LH 2 /LO 2 bipropellant produces higher I sp (due to higher chemical energy and lower exhaust molecular mass) but lower thrust than RP-1/LO 2 (due to higher density and propellant flow). In many cases, propulsion systems with very high specific impulse—some ion thrusters reach 25x-35x better I sp than chemical engines—produce ...
The type of jet engine used to explain the conversion of fuel into thrust is the ramjet.It is simpler than the turbojet which is, in turn, simpler than the turbofan.It is valid to use the ramjet example because the ramjet, turbojet and turbofan core all use the same principle to produce thrust which is to accelerate the air passing through them.