Properties
Air: R = 287 m²/(s² K), Cp = 1005 m²/(s² K), and y = 1.4
Jet fuel: hf (or QR) = 42.8 MJ/kg
Remember that 1 m²/(s² K) = 1 J/(kg K).
1) A Pratt & Whitney J57 turbojet engine is tested on a static thrust stand at sea-level
conditions (100 kPa). At a test point where the thrust is equal to 45 kN, the air and
fuel mass flow rates are 75 kg/s and 1 kg/s, respectively, and the exit pressure is
matched to the ambient.
Find: a) the exit velocity, b) the thermal efficiency