Frequency-tunable bracketless fluid manifold

Abstract

A method of assembling a fluid manifold includes: providing an array of spaced-apart manifold fittings, each manifold fitting having: a generally tubular neck; a pair of spaced-apart generally tubular arms extending away from a first end of the neck; and a coupling connected to a second end of the neck; and placing each manifold fitting in a predetermined angular orientation; and providing a plurality of curved tubes, and coupling one end of each tube to one arm of each of two adjacent ones of the manifold fittings, such that the assembled manifold has a predetermined first natural frequency.

What is claimed is: 
     
         1 . A method of assembling a fluid manifold, comprising:
 providing an array of spaced-apart manifold fittings, each manifold fitting comprising:
 a generally tubular neck; 
 a pair of spaced-apart generally tubular arms extending away from a first end of the neck; and 
 a coupling connected to a second end of the neck; and 
   placing each manifold fitting in a predetermined angular orientation; and   providing a plurality of curved tubes, and coupling one end of each tube to one arm of each of two adjacent ones of the manifold fittings, such that the assembled manifold has a predetermined first natural frequency.   
     
     
         2 . The method of  claim 1  wherein the coupling comprises an inner member and a collar surrounding the inner member. 
     
     
         3 . The method of  claim 2  wherein the collar is threaded and includes an annular flange which bears against a shoulder of the inner member. 
     
     
         4 . The method of  claim 1  further comprising connecting each of the couplings to a fuel nozzle inlet stem. 
     
     
         5 . The method of  claim 4  wherein each inlet stem includes an inlet fitting which includes:
 a ball-nose having a shape complementary to a seat defined by the inner member of the coupling; and 
 a resilient sealing element disposed in a groove in an outer surface of the inlet fitting. 
 
     
     
         6 . The method of  claim 4  wherein each of the fuel nozzle inlet stems is part of a fuel nozzle that is mounted to a combustor of a gas turbine engine, and the curved tubes are physically supported only by their connections to the fittings. 
     
     
         7 . The method of  claim 1  wherein each tube has a constant radius of curvature. 
     
     
         8 . The method of  claim 1  wherein the ends of the tubes are rigidly coupled to the arms of the manifold fittings. 
     
     
         9 . A method of configuring a fluid manifold including:
 an annular array of manifold fittings, each manifold fitting comprising:
 a generally tubular neck; 
 a pair of spaced-apart generally tubular arms extending away from a first end of the neck; and 
 a coupling connected to a second end of the neck; and 
   a plurality of curved tubes, the method comprising:   determining a desired natural frequency for the manifold as a whole; and   selecting a combination of:
 angular positions of the fittings; and 
 corresponding lengths of the curved tubes permitting one end of each tube to be coupled to one arm of each of two adjacent manifold fittings, such that the combination will result in the desired natural frequency; and 
   assembling the manifold using the selected combination of angular positions and curved tubes having the corresponding lengths.   
     
     
         10 . The method of  claim 9  wherein the coupling comprises an inner member and a collar surrounding the inner member. 
     
     
         11 . The method of  claim 10  wherein the collar is threaded and includes an annular flange which bears against a shoulder of the inner member. 
     
     
         12 . The method of  claim 9  further comprising connecting each of the couplings to a fuel nozzle inlet stem. 
     
     
         13 . The method of  claim 12  wherein each inlet stem includes an inlet fitting which includes:
 a ball-nose having a shape complementary to a seat defined by the inner member of the coupling; and 
 a resilient sealing element disposed in a groove in an outer surface of the inlet fitting. 
 
     
     
         14 . The method of  claim 12  wherein each of the fuel nozzle inlet stems is part of a fuel nozzle that is mounted to a combustor of a gas turbine engine, and the curved tubes are physically supported only by their connections to the fittings. 
     
     
         15 . The method of  claim 9  wherein each tube has a constant radius of curvature. 
     
     
         16 . The method of  claim 9  wherein the ends of the tubes are rigidly coupled to the arms of the manifold fittings.