Combustor

Abstract

A pressure rise combustor is provided with fuel provided at intermittent periods. The fuel is pulsed at timings such that the phase lag between the addition of the fuel and a resultant pressure rise is minimised. The fuel is pulsed such that the unsteady addition of heat reinforces the amplitude of an unsteady pressure fluctuation.

1 - 11 . (canceled) 
   
   
       12 . A method of operating a thermo acoustic pressure rise combustor having an air inlet, an exhaust, a combustion chamber and an associated fuel injector from which in use fuel is injected into the combustor chamber in pulses, the method comprising the steps of:
 introducing air and fuel into the combustor; and   inducing the air and fuel to ignite and deflagrate thereby creating a cyclical pressure fluctuation and pulsing fuel into the injector at the same frequency as the pressure fluctuation.   
   
   
       13 . A method according to  claim 12 , wherein the cyclical pressure fluctuation has a maxima and a minima with a pressure rising portion starting at the minima of the pressure fluctuation and extending to the maxima of the pressure fluctuation, the pressure falling portion starting at the maxima of the pressure fluctuation and extending to the minima of the pressure, wherein the timing of the start of the pulse of fuel is in a phase relationship with the pressure rising portion. 
   
   
       14 . A method according to  claim 12 , wherein the fuel flow is pulsed such that the fuel addition and/or heat addition to the combustor is non-sinusoidal. 
   
   
       15 . A method according to  claim 12 , wherein the cyclical pressure fluctuation is sinusoidal having a maxima and a minima with a pressure rising portion starting at the minima of the pressure fluctuation and extending to the maxima of the pressure fluctuation, wherein the timing of the start of the pulse of fuel is phased from the minima by between 0 degrees and 210 degrees. 
   
   
       16 . A method according to  claim 15 , wherein the timing of the start of the pulse of fuel is phased from the minima by between 90 degrees and 210 degrees. 
   
   
       17 . A method according to  claim 15 , wherein the timing of the end of the pulse of fuel is phased from the timing of the start of the pulse of fuel by a phase angle of between 30 degrees and 180 degrees. 
   
   
       18 . A method of operating a thermo acoustic pressure rise combustor comprising the steps of:
 introducing air and fuel into the combustor;   creating a cyclical pressure fluctuation having a minima and a maxima by inducing the air and fuel to ignite and deflagrate; and   pulsing fuel into the injector where the start of the pulse of fuel is phased from the minima of the pressure fluctuation at a phase angle delay of between 0 degrees and 210 degrees.   
   
   
       19 . A method according to  claim 18 , wherein the timing of the start of the pulse of fuel is phased from the minima by between 90 degrees and 210 degrees. 
   
   
       20 . A method according to  claim 18 , wherein the timing of the end of the pulse of fuel is phased from the timing of the start of the pulse of fuel by a phase angle of between 30 degrees and 180 degrees. 
   
   
       21 . A method according to  claim 18 , wherein the phase delay of the timing of the start of the pulse of fuel varies between cycles.