text: ., 
  
  The combustion of fuel in the afterburner 
  takes place at low pressures and is relatively 
  inefficient. This basic inefficiency of the low 
  pressure combustion is given evidence by the 
  large 
  increase in specific fuel combustion. 
  Generally, the use of afterburner at least will 
  double the specihtfuel consumption. As an 
  example, consider a turbojet engine capable 
  of producing 10,000 lbs. of thrust which can 
  develop 15,ooO lbs.. of thrust with 
  the use of 
  afterburner. Typical values for specific fuel 
  consumption would. be c,= 1.05 for the basic 
  engine or t,= 2.1 when the afterburner is in 
  use. The fuel flow during operation would be 
  as follows: 
  
  The aftsrbumer is a relatively simple means 
  of thrust augmentation and the principal fea- 
  tures are light weight and large thrust increase. 
  A typical afterburner installation may add only 
  10 to 20 percent of the basic engine wei,ght but 
  can provide a 40- to 60-percent increase in the 
  static sea level thrust. The afterburner con- 
  sists of an additional combustion area aft of 
  the turbine section with an arrangement of 
  fuel nozzles and flameholders. Because the 
  local flow velocities 
  in the afterburner are 
  quite high, the flameholders are necessary to 
  provide the turbulence to maintain combustion 
  within 
  the afterburner section. The turbojet 
  engine operates with airflows greatly in excess 
  of that chemically required to support combus- 
  tion of engine fuel. This is necessary because 
  of cooling requirements and turbine tempera- 
  ture limitations. Since only 15 to 30 percent 
  of the engine airflow is used in the combustion 
  chamber, the large excess air in the turbine 
  discharge can support combustion of large 
  fuel. Also, there are 
  amounts of additional 
  no highly stressed, rotating members in the 
  
  fuel flow = (thrust) (specific fuel consump- 
  
  tion) 
  
  without afterburner, 
  
  fuel flow=(10,000) 
  
  (1.05) 
  = 10,500 lbs./hr. 
  
  with afterburner, 
  
  fuel flow=(15,COO) (2.1) 
  =31,500 lbs./hr. 