Variable geometry rotating detonation combustor

Abstract

The present disclosure is directed to a method of operating a propulsion system at an approximately constant detonation cell quantity in the combustion chamber of a detonation combustion system. The propulsion system defines an inlet section upstream of the rotating detonation combustion system and an exhaust section downstream of the rotating detonation combustion system. The method includes providing an outer wall and an inner wall together defining an annular gap and a combustion chamber length extended from a combustion chamber inlet proximate to the fuel-oxidizer mixing nozzle to a combustion chamber exit proximate to the exhaust section of the propulsion system, the annular gap and the combustion chamber length together defining a first volume at a first operating condition defining a lowest steady state pressure and temperature at the rotating detonation combustion system; providing a mixture of a fuel and an oxidizer to the combustion chamber via the fuel-oxidizer mixing nozzle; detonating the fuel and oxidizer mixture in the combustion chamber, wherein the detonation produces a detonation cell size; and adjusting the volume of the combustion chamber via articulating one or more of the outer wall, the inner wall, and the fuel-oxidizer mixing nozzle such that one or more of the annular gap and the combustion chamber length is changed based on one or more operating conditions.

What is claimed is: 
     
         1 . A method of operating a propulsion system at an approximately constant detonation cell quantity in the combustion chamber of a detonation combustion system, the propulsion system defining an inlet section upstream of the rotating detonation combustion system and an exhaust section downstream of the rotating detonation combustion system, the method comprising:
 providing an outer wall and an inner wall together defining an annular gap and a combustion chamber length extended from a combustion chamber inlet proximate to the fuel-oxidizer mixing nozzle to a combustion chamber exit proximate to the exhaust section of the propulsion system, the annular gap and the combustion chamber length together defining a first volume at a first operating condition defining a lowest steady state pressure and temperature at the rotating detonation combustion system;   providing a mixture of a fuel and an oxidizer to the combustion chamber via the fuel-oxidizer mixing nozzle;   detonating the fuel and oxidizer mixture in the combustion chamber, wherein the detonation produces a detonation cell size; and   adjusting the volume of the combustion chamber via articulating one or more of the outer wall, the inner wall, and the fuel-oxidizer mixing nozzle such that one or more of the annular gap and the combustion chamber length is changed based on one or more operating conditions.   
     
     
         2 . The method of  claim 1 , wherein providing the outer wall and the inner wall defines a maximum annular gap and a maximum combustion chamber length at the first operating condition based on a desired detonation cell size. 
     
     
         3 . The method of  claim 1 , wherein adjusting the volume of the combustion chamber includes actuating one or more of the outer wall and the inner wall along a radial direction. 
     
     
         4 . The method of  claim 3 , wherein actuating one or more of the outer wall and the inner wall along the radial direction includes decreasing the annular gap at a second operating condition defining a pressure and temperature at the rotating detonation combustion system greater than the first operating condition. 
     
     
         5 . The method of  claim 1 , wherein adjusting the volume of the combustion chamber includes actuating the fuel-oxidizer mixing nozzle along a longitudinal direction. 
     
     
         6 . The method of  claim 5 , wherein actuating the fuel-oxidizer mixing nozzle along the longitudinal direction decreases the combustion chamber length at a second operating condition defining a pressure and temperature at the rotating detonation combustion system greater than the first operating condition. 
     
     
         7 . The method of  claim 1 , wherein adjusting the volume of the combustion chamber is based at least on maintaining an approximately constant detonation cell quantity at a second operating condition relative to the first operating condition, wherein the second operating condition defines a pressure and temperature at the rotating detonation combustion system greater than the first operating condition. 
     
     
         8 . The method of  claim 1 , further comprising:
 generating a flow of oxidizer to the fuel-oxidizer mixing nozzle based on a commanded operating condition of the propulsion system;   providing a flow of fuel to the fuel-oxidizer mixing nozzle based at least on a commanded operating condition of the propulsion system; and   adjusting one or more of a fuel and oxidizer condition based on the commanded operating condition.   
     
     
         9 . The method of  claim 8 , wherein adjusting one or more of a fuel and oxidizer condition based on the commanded operating condition of the propulsion system includes one or more of a fuel flow rate, a fuel pressure, a fuel temperature, an oxidizer flow rate, an oxidizer pressure, and an oxidizer temperature at the rotating detonation combustion system. 
     
     
         10 . The method of  claim 8 , wherein the commanded operating condition includes the first operating condition defining a lowest steady state pressure and temperature at the rotating detonation combustion system and a second operating condition defining one or more pressure and temperatures at the rotating detonation combustion system greater than the first operating condition. 
     
     
         11 . The method of  claim 1 , further comprising:
 determining a desired volume of the combustion chamber based on one or more of the annular gap and the combustion chamber length at a second operating condition greater than the first operating condition.   
     
     
         12 . The method of  claim 11 , wherein determining the desired volume of the combustion chamber includes determining an amount by which one or more of the outer wall and the inner wall articulates along the radial direction. 
     
     
         13 . The method of  claim 11 , wherein determining the desired volume of the combustion chamber includes determining an amount by which the fuel-oxidizer mixing nozzle articulates along the longitudinal direction. 
     
     
         14 . The method of  claim 11 , wherein determining the desired volume is based on one or more of a look-up table, a schedule, a transfer function, and one or more performance maps. 
     
     
         15 . The method of  claim 11 , wherein determining the desired volume is based at least on a detonation cell size relative to one or more of a pressure, temperature, and flow rate of the fuel and the oxidizer versus a range of volumes of the combustion chamber corresponding to the desired detonation cell quantity. 
     
     
         16 . The method of  claim 15 , wherein the desired detonation cell quantity is approximately equal at the first operating condition and a second operating condition greater than the first operating condition. 
     
     
         17 . The method of  claim 15 , wherein the range of volumes comprises a range at which one or more of the outer wall and the inner wall articulates along the radial direction to define a range of annular gaps. 
     
     
         18 . The method of  claim 17 , wherein the range of volumes comprises a fixed combustion chamber length at a second operating condition equal to the first operating condition. 
     
     
         19 . The method of  claim 15 , wherein the range of volumes comprises a range at which fuel-oxidizer mixing nozzle articulates along the longitudinal direction to define a range of combustion chamber lengths. 
     
     
         20 . The method of  claim 1 , further comprising:
 monitoring a detonation stability of the detonated fuel-oxidizer mixture; and   determining a desired volume of the combustion chamber based the monitored detonation stability.