Find the thrust from the engine

In summary, a static thrust stand is being designed to test a jet engine. The inlet conditions include an inlet area of 1 {m2}, inlet velocity of 250 {m/s}, and gage static pressure of -22.5 {kPa}. The expected conditions at the 0.3 {m2} outlet are an exhaust gas velocity of 444 {m/s}, gage static pressure of 0 {kPa}, and temperature of 268 {K}. Given these conditions, the thrust produced by the engine is calculated to be 402.5 kN, assuming constant mass flow rate through the engine and atmospheric pressure. However, it is important to note that this calculation is based on Bernoulli's equation
  • #1
jdawg
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2

Homework Statement


A static thrust stand is to be designed for testing a jet engine. The inlet conditions for the test are an inlet area of 1 {m2}, inlet velocity of 250 {m/s}, and gage static pressure of -22.5 {kPa}. The expected conditions at the 0.3 {m2} outlet are an exhaust gas velocity of 444 {m/s}, gage static pressure of 0 {kPa} and temperature of 268 {K}. Find the thrust the engine produces. Assume constant mass flow rate through the engine (i.e. mass of fuel in negligible) and that the gauge pressure is atmospheric pressure

Homework Equations

The Attempt at a Solution


First I calculated the total pressure entering and exiting the turbine:
(ρv2/2)+P+ρgh=Ptotal

The first term being dynamic pressure, the second being static pressure, and the third being hydrostatic pressure. I assumed hydrostatic pressure was negligible since I was given no information about the height.

Ptotal,1=15.78 kPa
Ptotal,2=120.75 kPa

Then I used F=P2A2
And found the force to be 402.5 kN

Does what I did make sense? I'm not really sure if this is the proper way to find the force of the thrust.
 
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  • #2
Bernoulli's equation is based on conservation of energy. I would guess the engine is adding quite a bit.
What is the mass flow rate?
What is the rate of change of momentum of the air flowing through?
 

1. What is thrust from the engine?

Thrust from the engine is the force that propels an aircraft or other object forward. It is generated by the propulsion system, such as a jet engine, and is necessary for the object to overcome drag and move through the air.

2. How is thrust from the engine calculated?

Thrust from the engine is calculated by multiplying the mass flow rate of the engine's exhaust by the velocity of the exhaust gases. This calculation is known as the thrust equation and is a fundamental concept in aerodynamics.

3. What factors affect the thrust from the engine?

The thrust from an engine can be affected by various factors such as the design and efficiency of the engine, the air density, and the speed of the object. Other factors that can impact thrust include altitude, temperature, and humidity.

4. How does thrust from the engine impact flight?

Thrust from the engine is essential for flight as it provides the necessary force to overcome drag and lift the aircraft off the ground. Without sufficient thrust, an aircraft would not be able to maintain level flight or reach desired speeds.

5. Can the thrust from an engine be controlled?

Yes, the thrust from an engine can be controlled by adjusting the engine's throttle or by changing the direction of the exhaust gases through the use of flaps or nozzles. This allows for changes in speed, altitude, and direction during flight.

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