Flame control in the buoyancy-dominated fluid dynamics region

Abstract

A burner system includes a nozzle configured to emit a fuel stream for the support of a flame, and first and second electrodes, each configured to apply electrical energy to a flame supported by the nozzle. The first electrode is positioned in a momentum-dominated fluid dynamics region of the flame, while the second electrode is positioned in a buoyancy-dominated fluid dynamics region. Application of charges to the flame via the electrodes can be employed to control flame characteristics in the buoyancy-dominated fluid dynamics region, such as shape and position.

What is claimed is: 
     
         1 . A method for controlling a characteristic of a flame in a burner system, comprising:
 supporting a flame in a fuel stream; and   modifying a characteristic of the flame by:
 applying a first electric charge to the flame at a first location that is upstream from a buoyancy-dominated flow region of the flame, and 
 applying a second electric charge to the flame at a second location that is downstream from a momentum-dominated flow region of the flame, such that the first and second electric charges interact. 
   
     
     
         2 . The method of  claim 1 , comprising identifying a transition point between the momentum-dominated flow region of the flame and the buoyancy-dominated flow region of the flame. 
     
     
         3 . The method of  claim 1 , comprising identifying the buoyancy-dominated flow region of the flame, and selecting the second location to be within the buoyancy-dominated flow region. 
     
     
         4 . The method of  claim 1 , comprising identifying the momentum-dominated flow region of the flame, and selecting the first location to be within the momentum-dominated flow region. 
     
     
         5 . The method of  claim 1 , wherein the applying a first electric charge comprises charging the flame at a first polarity. 
     
     
         6 . The method of  claim 5  wherein the applying a second electric charge comprises generating an electric field between an electrode and the flame. 
     
     
         7 . The method of  claim 6 , wherein the generating an electric field comprises:
 providing a dielectric gap between the electrode and the flame; and   applying a voltage having a second polarity, opposite the first polarity, to the electrode.   
     
     
         8 . The method of  claim 5  wherein the charging the flame at a first polarity comprises: applying a voltage potential to an electrode in electrical contact with the flame. 
     
     
         9 . The method of  claim 8  wherein:
 the supporting a flame in a fuel stream comprises ejecting fuel from a nozzle; and 
 the applying a voltage potential to an electrode in electrical contact with the flame comprises applying a voltage potential to the nozzle. 
 
     
     
         10 . The method of  claim 5  wherein the charging the flame at a first polarity comprises introducing ions into the flame. 
     
     
         11 . The method of  claim 10  wherein the introducing ions into the flame comprises:
 generating ions having the first polarity; and 
 entraining the ions into the flame. 
 
     
     
         12 . The method of  claim 10  wherein the introducing ions into the flame comprises:
 ejecting ions from a corona electrode by applying a first voltage potential having the first polarity to a corona electrode positioned adjacent to the flame while simultaneously applying a second voltage potential having a second polarity, opposite the first polarity, to a counter electrode positioned adjacent to the flame on a side opposite the corona electrode; and 
 entraining the ions into the flame. 
 
     
     
         13 . The method of  claim 1 , wherein:
 the applying a first electric charge comprises applying a first electric charge having a first polarity; and   the applying a second electric charge comprises applying a second electric charge having a second polarity, opposite the first polarity.   
     
     
         14 . The method of  claim 1  wherein:
 the applying a first electric charge comprises applying a first electric charge having a first polarity; and 
 the applying a second electric charge comprises applying a first voltage having the first polarity to a first electrode positioned adjacent to the flame while applying a second voltage having a second polarity, opposite the first polarity, to a second electrode positioned adjacent to the flame on a side of the flame substantially opposite the first electrode. 
 
     
     
         15 . The method of  claim 1  wherein:
 the applying a first electric charge comprises applying a first electric charge having a first polarity; and 
 the applying a second electric charge comprises forming an electric field across the flame at the second location, by applying a first voltage having the first polarity to a first electrode positioned adjacent to the flame while applying a second voltage having a second polarity, opposite the first polarity, to a second electrode positioned adjacent to the flame on a side of the flame substantially opposite the first electrode. 
 
     
     
         16 . The method of  claim 1 , wherein the applying a second electric charge comprises: applying a second electric charge having a same polarity as the first electric charge. 
     
     
         17 . The method of  claim 1  wherein:
 the applying a first electric charge comprises applying a first voltage potential to a first electrode positioned adjacent to the flame at the first location; and 
 the applying a second electric charge comprises applying a second voltage potential to a second electrode positioned adjacent to the flame at the second location. 
 
     
     
         18 . The method of  claim 17  wherein:
 the applying a first voltage potential comprises applying the first voltage potential having a first polarity to the first electrode; and 
 the applying a second voltage potential comprises applying the second voltage potential having a second polarity, opposite the first polarity, to the second electrode. 
 
     
     
         19 . The method of  claim 1  wherein:
 the applying a first electric charge comprises applying a first voltage potential to a first electrode positioned adjacent to the flame at the first location and having annular shape; and 
 the applying a second electric charge comprises applying a second voltage potential to a second electrode positioned adjacent to the flame at the second location. 
 
     
     
         20 . The method of  claim 1  wherein:
 the applying a first electric charge comprises applying a first voltage potential to a first electrode positioned adjacent to the flame at the first location; and 
 the applying a second electric charge comprises applying a second voltage potential to a second electrode positioned adjacent to the flame at the second location and having an annular shape. 
 
     
     
         21 . A method for controlling a characteristic of a flame in a burner system, comprising:
 supporting a flame in a fuel stream;   identifying a flame holding region of the flame, a momentum-dominated flow region of the flame, and a buoyancy-dominated flow region of the flame;   modifying a characteristic of the flame by:
 applying a first electric charge to the flame at a first location that is upstream from the buoyancy-dominated flow region of the flame, and 
 applying a second electric charge to the flame at a second location that is downstream from the momentum-dominated flow region of the flame, such that the first and second electric charges interact. 
   
     
     
         22 . A method for controlling a characteristic of a flame in a burner system, comprising:
 in a fuel stream, supporting a flame that is characterized by a momentum-dominated flow region and buoyancy-dominated flow region, each having dimensions sufficient for the application of electrical energy;   modifying a characteristic of the flame by:
 applying a first electric charge to the flame at a first location that is upstream from the buoyancy-dominated flow region of the flame, and 
 applying a second electric charge to the flame at a second location that is downstream from the momentum-dominated flow region of the flame, such that the first and second electric charges interact.