text: compressor pressure ratio should be high 
  to 
  produce a high thermal efliciency in the engine 
  The area XCDZ represents the work done by 
  the compressor during the compression of the 
  unit weight of air. Of course, certain losses 
  and inefliciencies are incurred during the com- 
  pression and the power required to operate the 
  compressor will be greater than that indicated 
  by the work done on the engine airflow. 
  
  known for converting fuel energy into propul- 
  sive energy. However, the intermittent action 
  of the reciprocating engine places practical 
  limits to the airflow that can be processed and 
  restricts the development of power. The con- 
  tinuous, steady flow feature of the gas turbine 
  allows such a powerplant to process consider- 
  ably greater airflow and, thus, utilize a greater 
  the pro- 
  expenditure of fuel energy. While 
  pulsive efficiency of the turbojet engine is con- 
  siderably below that of the reciprocating en- 
  gine-propeller combination, the specific power 
  output of the turbojet at high speeds is quite 
  superior. 
  
  Compressed air is discharged from the com- 
  pressor to the combustion chamber at condition 
  D. Fuel is added in the combustion chamber, 
  and the combustion of fuel liberates consider- 
  able heat energy. The combustion process in 
  the gas turbine differs from that of the recipro- 
  cating engine in that the process is essentially 
  a constant pressure addition of heat energy. 
  As a result, the combustion of fuel causes a 
  large change in temperature and large change 
  of volume of the unit weight of airflow. The 
  process in the combustion chamber is repre- 
  sented by the change from point D to point E of 
  the pressure-volume diagram of figure 2.6. 