EFFECT OF THERMODYNAMIC VARIABLES ON ENGINE PERFORMANCE

EFFECT OF THERMODYNAMIC VARIABLES ON ENGINE PERFORMANCE

Figure 1.1 presents a sketch of an elementary gas turbine engine. A
compressor converts mechanical energy into pneumatic energy and raises
the total pressure of the air between stations 2 and 3. (The station numbers
conform to a standard form, see Fig. 5.1 of Ref. 1.) When the engine is in
forward motion, additional pneumatic energy converts the kinetic energy of
the relative motion into pressure. Combustion of fuel in the burner adds
heat and raises the air temperature between stations 3 and 4. The turbines
between stations 4 and 5 convert part or nearly all of the available energy
at station 4 into mechanical energy. Part of this mechanical energy is
transferred to the compressor to effect the compression between stations 2
and 3. Additional mechanical energy may be transferred through a propulsion
device such as propeller or fan. Any pneumatic energy remaining at
station 5 is used to accelerate the gas to the velocity Vj and the kinetic
energy of ~V 2 per unit mass of air represents additional power output
from the engine. Heat may be added in an afterburner to further increase
and the output power.