text: In most cases, the deceleration fuel flow 
  boundary is considerably below the steady 
  state fuel flow and no great problem exists in 
  obtaining satisfactory deceleration character- 
  istics. 
  In fact, the greater problem is con- 
  cerned with obtaining proper acceleration 
  characteristics. For the majority of centrifu- 
  gal flow engines, the acceleration boundary is 
  set usually by temperature limiting conditions 
  rather than compressor surge conditions. Peak 
  operating efficiency of the centrifugal com- 
  pressor is obtained at flow conditions which 
  are below the surge limit, hence acceleration 
  fuel flow boundary is determined by turbine 
  temperature limits. The usual result is that 
  In order for the powerplant to achieve mini- 
  mum acceleration times, the fuel control must 
  provide acceleration fuel 
  flow as close as 
  practical to the acceleration boundary. Thus, 
  a maximum controlled acceleration may pro- 
  duce limiting 
  temperatures or 
  slight incipient stall-surge of the compressor. 
  Proper maintenance and adjustment of 
  the 
  engine governing apparatus is essential to 
  produce minimum acceleration times without 
  incurring excessive temperatures or heavy stall- 
  surge conditions. 
  
  turbine  inlet 
  
  123 