text: The operation of the turbojet engine involves 
  a relatively large change in velocity being im- 
  parted to the mass flow through 
  the engine. 
  Figure 2.6 illustrates the operation of a typical 
  turbojet engine by considering the processing 
  given a unit weight of inlet airflow. Consider 
  a unit weight of ambient air approaching the 
  inlet 
  the engine then experiencing the 
  changes in pressure and volume as it is proc- 
  essed by’the 
  turbojet. The chart of pressure 
  versus volume of figure 2.6 shows that the unit 
  weight of airflow at atmospheric condition A 
  is delivered to the inlet entrance at condition 
  B. The purpose of the inlet or diffuser as to 
  reduce the velocity and increase the pressure 
  of the flow entering the compressor section. 
  Thus, the aerodynamic compression produces 
  an increase in pressure and decrease in volume 
  of the unit weight of air and delivers air to 
  the compressor at condition C. The work done 
  by the aerodynamic compression of the inlet 
  ot diffuser is represented by the area ABCX. 
  Generally, most conventional turbojet engines 
  require that the compressor inlet flow be sub- 
  sonic and supersonic flight will 
  involve con- 
  siderable aerodynamic compression in the inlet. 
  Air delivered to the compressor inlet at con- 
  dition C is then subject to further compression 
  through the compressor section. As a result 
  of the function of the compressor, the unit 
  weight of air is subject to a decrease in volume 
  and increase in pressure to condition D. The 