Annular combustion chamber with two offset heads

Abstract

An offset annular combustion chamber for an airplane engine gas turbine, the chamber comprising a pilot head having a plurality of nozzle systems distributed on a pilot head chamber end wall interconnecting an inner longitudinally-extending side wall of the chamber to a pilot head outer longitudinally-extending side wall, and a take-off head that is radially and axially offset from the pilot head and comprising a plurality of nozzle systems distributed on a take-off head chamber end wall interconnecting the pilot head outer longitudinally-extending side wall and a take-off head outer longitudinally-extending side wall, the pilot head having at least N substantially identical nozzle systems with overall permeability PA adapted to lighting and to speeds close to idling, and the take-off head having at least 2N substantially identical nozzle systems of overall permeability PB, where PB is greater than or equal to PA, the permeability PA lying in the range 10% to 40% of the total air flow rate penetrating into the chamber and the permeability PB lying in the range 30% to 70% of the total air flow rate penetrating into the chamber.

1 / An offset annular combustion chamber for an airplane engine gas turbine, the chamber comprising a pilot head having a plurality of nozzle systems distributed on a pilot head chamber end wall interconnecting an inner longitudinally-extending side wall of the chamber to a pilot head outer longitudinally-extending side wall, and a take-off head that is radially and axially offset from the pilot head and comprising a plurality of nozzle systems distributed on a take-off head chamber end wall interconnecting the pilot head outer longitudinally-extending side wall and a take-off head outer longitudinally-extending side wall, the pilot head having at least N substantially identical nozzle systems with overall permeability PA adapted to lighting and to speeds close to idling, and the take-off head having at least 2N substantially identical nozzle systems of overall permeability PB, where PB is greater than or equal to PA, wherein the permeability PA lies in the range 10% to 40% of the total air flow rate penetrating into the chamber and the permeability PB lies in the range 30% to 70% of the total air flow rate penetrating into the chamber.  
     
     
         2 / A chamber according to  claim 1 , wherein the permeability PA lies in the range 17% to 21% of the total air flow rate penetrating into the chamber.  
     
     
         3 / A chamber according to  claim 1 , wherein the permeability PB lies in the range 36% to 45% of the total air flow rate penetrating into the chamber.  
     
     
         4 / A chamber according to  claim 1 , further comprising a plurality of external dilution orifices opening out at least through the outer longitudinally-extending side wall of the take-off head.  
     
     
         5 / A chamber according to  claim 4 , having at least one row of 2N outer dilution orifices opening out substantially perpendicularly to the outer longitudinally-extending side wall of the take-off head.  
     
     
         6 / A chamber according to  claim 4 , wherein the air flow rate penetrating via the outer dilution orifices lies in the range 4% to 10% of the total air flow rate penetrating into the chamber.  
     
     
         7 / A chamber according to  claim 1 , having a plurality of inner dilution orifices opening out through the inner longitudinally-extending side wall of the chamber.  
     
     
         8 / A chamber according to  claim 7 , wherein the air flow rate penetrating via the inner dilution orifices lies in the range 2% to 8% of the total air flow rate penetrating into the chamber.  
     
     
         9 / A chamber according to  claim 1 , wherein the nozzle systems of the pilot head and of the take-off head are disposed substantially in a staggered configuration.  
     
     
         10 / A chamber according to  claim 1 , wherein the axes of the nozzle systems of the pilot head and of the take-off head are directed towards a common annular zone for exhausting the gases generated by combustion.  
     
     
         11 / A chamber according to  claim 1 , wherein the chamber end walls of the pilot and take-off heads are walls extending perpendicularly to the axis of the engine.  
     
     
         12 / A chamber according to  claim 1 , wherein the chamber end walls of the pilot and take-off heads are walls of frustoconical shape.  
     
     
         13 / A chamber according to  claim 1 , wherein each nozzle system of the pilot and take-off heads comprises a fuel nozzle, a primary air swirler and a secondary air swirler that are fed radially, a Venturi situated on the axis of the nozzle between the primary and secondary air swirlers in order to encourage breaking up of the fuel into fine droplets, and ventilation holes opening out close to a tip of the nozzle.  
     
     
         14 / A chamber according to  claim 13 , wherein the set of pilot head nozzle systems is provided with fairing so as to minimize head losses in the air that flows round the pilot head.