UNIFIED ENGINEERING                                                               Spring 2006

                                                                                                             Ian A. Waitz

Problem P2. (Unified Propulsion) L.O.’s A & B

Below is a schematic of an annular inlet nozzle for a gas turbine engine with flight velocity, uo, and a nozzle velocity uN—both velocities are given in the reference frame of the engine and the flow is purely axial when it crosses the upstream and downstream boundaries of the control volume.  Flow is left to right.  Assume that the flow is steady, inviscid and incompressible; you will use Bernoulli’s equation to relate the conditions in the inlet to those far upstream. 

For this problem, you are to determine if the pressure forces on the inlet nozzle put the structure in compression or tension axially (neglecting the weight of the nozzle).

a) Write an expression for the force, Fs, that must be applied to the inlet nozzle structure in terms of the fluid density, r, and uo, uN, and AN.

b) Is the nozzle inlet structure in tension and compression axially?  Why?  What is the physical reason for this behavior?