Multiwall tube and fitting for bearing oil supply

Abstract

A multiwall tubing assembly for fluid delivery to a bearing system may comprise a first tube defining an inner fluid passage configured to carry a first fluid. A second tube may be disposed around the first tube and may define an outer fluid passage between the first tube and the second tube. The outer fluid passage may be configured to carry a second fluid. A fitting may be coupled to the first tube and the second tube. The fitting may comprise an inner portion fluidly coupled to the inner fluid passage and configured to carry the first fluid. An outer portion may be disposed around the inner portion and fluidly coupled to the outer fluid passage. The outer portion may be configured to carry the second fluid. The fitting may be configured to fluidly isolate the first fluid from the second fluid.

What is claimed is: 
     
       1. A multiwall tubing assembly for fluid delivery to a bearing system, comprising:
 a first tube defining an inner fluid passage configured to carry a first fluid; 
 a second tube disposed around the first tube and defining an outer fluid passage between the first tube and the second tube, the outer fluid passage configured to carry a second fluid; 
 a third tube disposed around the second tube and defining a chamber between the second tube and the third tube, the chamber being fluidly isolated from the outer fluid passage; and 
 a fitting coupled to the first tube and the second tube, the fitting comprising: an inner portion fluidly coupled to the inner fluid passage and configured to carry the first fluid, and 
 an outer portion disposed around the inner portion and fluidly coupled to the outer fluid passage, the outer portion configured to carry the second fluid, 
 wherein the fitting is configured to fluidly isolate the first fluid from the second fluid. 
 
     
     
       2. The multiwall tubing assembly of  claim 1 , wherein the outer fluid passage is concentric with the inner fluid passage. 
     
     
       3. The multiwall tubing assembly of  claim 1 , wherein the fitting is configured to couple to a bearing housing of the bearing system with the inner fluid passage in fluid communication with a bearing damper path defined by the bearing housing, and with the outer fluid passage in fluid communication with a bearing compartment path defined by the bearing housing. 
     
     
       4. The multiwall tubing assembly of  claim 3 , wherein a pressure of the first fluid is greater than a pressure of the second fluid. 
     
     
       5. The multiwall tubing assembly of  claim 1 , wherein the outer portion of the fitting defines a first aperture disposed through a sidewall of the outer portion. 
     
     
       6. The multiwall tubing assembly of  claim 1 , wherein the outer portion of the fitting comprises a frustoconical portion, and wherein the inner portion of the fitting comprises a tubular portion. 
     
     
       7. A mid-turbine frame for a gas turbine engine, comprising:
 a bearing system including a bearing housing; 
 a first tube defining an inner fluid passage configured to carry a first fluid to the bearing system; 
 a second tube disposed around the first tube and defining an outer fluid passage between the first tube and the second tube, the outer fluid passage configured to carry a second fluid to the bearing system; 
 a third tube disposed around the second tube and defining a chamber between the second tube and the third tube, the chamber being fluidly isolated from the outer fluid passage; and 
 a fitting coupled to the bearing housing and to the first tube and the second tube, the fitting comprising:
 an inner portion fluidly coupled to the inner fluid passage and configured to carry the first fluid to the bearing system, and 
 an outer portion disposed around the inner portion and fluidly coupled to the outer fluid passage, the outer portion configured to carry the second fluid to the bearing system, 
 wherein the fitting is configured to fluidly isolate the first fluid from the second fluid. 
 
 
     
     
       8. The mid-turbine frame of  claim 7 , wherein the outer fluid passage is concentric with the inner fluid passage. 
     
     
       9. The mid-turbine frame of  claim 7 , wherein the bearing system further comprises a bearing damper and a bearing chamber, and wherein the bearing housing defines a bearing damper path and a bearing chamber path. 
     
     
       10. The mid-turbine frame of  claim 9 , wherein the inner fluid passage is in fluid communication with the bearing damper path, and wherein the outer fluid passage is in fluid communication with the bearing chamber path. 
     
     
       11. The mid-turbine frame of  claim 7 , wherein the outer portion of the fitting defines an aperture disposed through a sidewall of the outer portion. 
     
     
       12. The mid-turbine frame of  claim 7 , wherein the outer portion of the fitting comprises a frustoconical portion, and wherein the inner portion of the fitting comprises a tubular portion. 
     
     
       13. The mid-turbine frame of  claim 7 , further comprising a seal disposed between the bearing housing and the fitting, the seal configured to maintain fluid isolation of the first fluid from the second fluid. 
     
     
       14. A method of delivering lubricant to a bearing system, comprising:
 coupling a fitting to a first tube, wherein the first tube defines a first fluid path; 
 disposing the first tube within a second tube, wherein the first tube and the second tube define a second fluid path between the first tube and the second tube; 
 coupling the second tube to the fitting, wherein the fitting is configured to fluidly isolate a second fluid in the second fluid path from a first fluid in the first fluid path; 
 delivering the first fluid through the first fluid path to the bearing system during engine startup; and 
 coupling the fitting to a bearing housing, wherein the first fluid path is in fluid communication with a bearing damper path defined by the bearing housing, and wherein the second fluid path is in fluid communication with a bearing compartment path defined by the bearing housing. 
 
     
     
       15. The method of  claim 14 , further comprising delivering the second fluid through the second fluid path to the bearing system during engine startup, wherein a pressure of the first fluid during engine startup is greater than a pressure of the second fluid during engine startup. 
     
     
       16. The method of  claim 14 , wherein the delivering the first fluid further comprises delivering the first fluid to a bearing damper. 
     
     
       17. The method of  claim 16 , wherein the delivering the second fluid further comprises delivering the second fluid to a bearing compartment.