Method and burner for manufacturing a glass optical fibre preform by vapour deposition

Abstract

A method is disclosed for feeding a flow of gas to a burner for manufacturing an optical fibre preform, said burner comprising: a plurality of coaxial tubes, each two adjacent coaxial tubes defining an annular channel between themselves; an annular gas distribution chamber at one extremity of said annular channels and in fluid communication therewith, said annular distribution chamber being delimited in the radial direction by an inner and an outer surface; said method comprising introducing the flow of gas into the distribution chamber so that the direction of its radially outermost portion is tangential to the radially outer surface of the distribution chamber. The method allows obtaining a better gas velocity distribution in said annular channels. A burner for performing said method is also disclosed.

1 . A method for feeding a flow of gas to a burner for manufacturing an optical fibre preform, said burner comprising:
 a plurality of coaxial tubes, each two adjacent coaxial tubes defining an annular channel between themselves;   an annular gas distribution chamber at one extremity of at least one of said annular channels and in fluid communication therewith, said annular distribution chamber being delimited to the radial direction by an inner and an outer surface; and   a feeding duct to feed a flow of gas into said distribution chamber,   said method comprising the step of introducing the gas into said distribution chamber in a direction not intersecting the axis of said coaxial tubes and lying on a plane transversal thereto.   
   
   
       2 . The method according to  claim 1 , wherein the direction of the gas being introduced into said distribution chamber lies on a plane perpendicular to the axis of said coaxial tubes. 
   
   
       3 . The method according to  claim 2 , wherein the direction of the gas being introduced into said distribution chamber does not intersect the inner surface of said distribution chamber. 
   
   
       4 . The method according to  claim 3 , wherein the direction of the radially outermost portion of said flow of gas, being introduced into said distribution chamber, is substantially tangential to the outer surface of said distribution chamber. 
   
   
       5 . The method according to any one of the preceding claims, further comprising conferring to said flow of gas a direction substantially parallel to the axis of said coaxial tubes along said annular channel. 
   
   
       6 . The method according to  claim 5 , wherein said direction is conferred by flowing said gas through a layer of porous material. 
   
   
       7 . The method according to  claim 6 , wherein the layer of porous material is placed between said distribution chamber and said annular channel. 
   
   
       8 - 12 . (canceled)