Linear Momentum Balance in Aerodynamic Thrust

velocity in (m/s)

150

inlet radius (m)

1

outlet radius (m)

0.75

inlet pressure (kPa)

0

density kg/

3

m



1

The force generated by a jet engine on a static thrust stand can be determined using Newton's second law of motion, in which the time rate of change of the linear momentum of the system is equal to the sum of external forces acting on the system. For a fixed, nondeforming control volume with uniform and steady flow, the sum of the forces is equal to the net rate of linear momentum flow through each control surface. This Demonstration illustrates the effects of air density, intake velocity and pressure, and control surface areas on the resultant anchoring force (

F

x

) necessary to hold the jet engine stationary.