How do you determine the thrust of a jet engine.?

Question

How do you determine the thrust of a jet engine.?

Answer 1

Contact the manufacturer. If that is not feasable you would have to calculate the CFM based on fuel consumption and air intake. Temperature would also be a factor both on the intake and exhaust.

And what type of jet engine are you talking about? Turbojet or turbofan?

Answer 2

Jet engines move the airplane forward with a great force that is produced by a tremendous thrust and causes the plane to fly very fast.

All jet engines, which are also called gas turbines, work on the same principle. The engine sucks air in at the front with a fan. A compressor raises the pressure of the air. The compressor is made up of fans with many blades and attached to a shaft. The blades compress the air. The compressed air is then sprayed with fuel and an electric spark lights the mixture. The burning gases expand and blast out through the nozzle, at the back of the engine. As the jets of gas shoot backward, the engine and the aircraft are thrust forward.

The image above shows how the air flows through the engine. The air goes through the core of the engine as well as around the core. This causes some of the air to be very hot and some to be cooler. The cooler air then mixes with the hot air at the engine exit area.

A jet engine operates on the application of Sir Isaac Newton's third law of physics: for every action there is an equal and opposite reaction. This is called thrust. This law is demonstrated in simple terms by releasing an inflated balloon and watching the escaping air propel the balloon in the opposite direction. In the basic turbojet engine, air enters the front intake and is compressed, then forced into combustion chambers where fuel is sprayed into it and the mixture is ignited. Gases which form expand rapidly and are exhausted through the rear of the combustion chambers. These gases exert equal force in all directions, providing forward thrust as they escape to the rear. As the gases leave the engine, they pass through a fan-like set of blades (turbine) which rotates the turbine shaft. This shaft, in turn, rotates the compressor, thereby bringing in a fresh supply of air through the intake. Engine thrust may be increased by the addition of an afterburner section in which extra fuel is sprayed into the exhausting gases which burn to give the added thrust. At approximately 400 mph, one pound of thrust equals one horsepower, but at higher speeds this ratio increases and a pound of thrust is greater than one horsepower. At speeds of less than 400 mph, this ratio decreases.

In a turboprop engine, the exhaust gases are also used to rotate a propeller attached to the turbine shaft for increased fuel economy at lower altitudes. A turbofan engine incorporates a fan to produce additional thrust, supplementing that created by the basic turbojet engine, for greater efficiency at high altitudes. The advantages of jet engines over piston engines include lighter weight with greater power, simpler construction and maintenance with fewer moving parts, and efficient operation with cheaper fuel.

Answer 3

What image above?  Imagine a bottle rocket with a weight tied to the end of the stick. The pounds of thrust equal the amount of weight (including the bottle rocket) that the "thrust" could lift off the ground.

Now take your rocket or jet engine, put wheels on it, and place it on a level railroad track.  Put a big super heavy duty scale on the front like the kind they weigh trucks with. Place something that wont move no matter what on the tracks.  Now put your jet train car against that un-moveable object and use it to crush that scale with as many pounds of thrust as you can.

Is this making sense to you yet? If not, I'm going to go kill myself right now.

Answer 4

There's some algorithm.

Answer 5

The simple answer is Force (thrust)= Mass of Air X Acceleration of the air

F=MA

Answer 6

Simply... the engine is mounted to a frame that has force sensors and is operated at max power in an area that is called the test cell.  All turbine engines go through this test and then the thrust rating is stamped on the data plate on the engine