__T-s Diagram__

__Example Problem__

A
turbofan engine operates at intermediate thrust (afterburner off) with the
following characteristics:

Flight
condition:

Ambient
temperature = 298.15K

Ambient
pressure = 101300N/m2.

Bypass
ratio b = 0.6

Compressor
pressure ratio p_{c} = 25

Fan
pressure ratio p_{f} = 3.375

Fuel
heating value q_{r} =
19000Btu/lbm

Turbine
inlet temperature = 2000K

Diffuser
pressure recovery factor r_{d}
= 0.9

Compressor
efficiency h_{c} = 0.89

Fan
efficiency h_{f}
= 0.91

Combustion
efficiency h_{b} = 0.98

Burner
pressure recovery factor r_{b}= 0.95

Turbine
efficiency h_{t}
= 0.98

Nozzle
efficiency h_{n }= 1.0

Calculate
the thrust per unit mass flow rate, and the thrust specific fuel consumption.
Later, for a specified value of thrust, determine the area at the choked
turbine exit, which limits the mass flow rate.

Such a problem can be solved by going
station by station through the engine and using simple thermodynamic relations.
Since the component efficiencies are specified, we don't have to go into
detailed multi-dimensional flow and chemical analyses for each component.

__ANALYSIS__

*Station 1:
inlet*

p01 = p0a: isentropic external acceleration or deceleration

T01 = T0a: no work done, except that of expansion or contraction.>

*Station 2: end
of diffuser, beginning of compressor & fan:*

T02 = T01: adiabatic, no work

p02= rdp01: includes the given stagnation pressure loss