text: Mach number ahead of the wave is 1.25, 
  the Mach number of the flow behind the 
  wave is approximately 0.80. 
  
  (2) The airflow direction 
  behind the wave is unchanged. 
  
  immediately 
  
  (3) The static pressure of the airstream 
  
  behind the wave is increased greatly. 
  
  (4) The density of the airstream behind 
  
  the wave is increased greatly. 
  
  (5) The energy of the airstream (indi- 
  cated by total pressure-dynamic plus static) 
  is greatly reduced. The normal shock wave 
  is very wasteful of energy. 
  EXPANSION WAVE. 
  
  If a supersonic air- 
  stream were turned away from the preceding 
  form. The 
  flow an expansion wave would 
  flow “around a corner” shown in figure 3.7 
  will not cause sharp, sudden changes in the 
  airflow except at the corner itself and thus is 
  not actually a “shock” wave. A supersonic 
  airstream passing through an expansion wave 
  will experience these changes: 
  
  (1) The airstream is accelerated; the ve- 
  locity and Mach number behind the wave 
  are greater. 
  (2) The  flow direction 