Helical Formation for a Conduit

Abstract

A helical formation within a conduit and a method of determining the helix angle of the helical formation are disclosed. The method includes specifying the internal dimensions of the conduit and an intended fluid mass flow through the conduit. The helix angle is determined from the pressure drop and the turbulent kinetic energy for a conduit having the specified internal dimensions and intended fluid mass flow.

1 . A helical formation for a conduit, the helical formation defining at least a portion of a helix, the helical formation being made by a process comprising the steps of:
 (i) determining an angle of the helix defined by the helical formation from the internal dimensions of the conduit, the fluid mass flow of the conduit, the pressure drop along the conduit and the turbulent kinetic energy within the conduit; and   (ii) producing the helical formation with the helix angle as determined in step (i).   
   
   
       2 . A helical formation according to  claim 1 , wherein the helix angle is between 5° and 50°. 
   
   
       3 . A helical formation according to  claim 1 , wherein the helix angle is between 5° and 20°. 
   
   
       4 . A helical formation according to  claim 1 , wherein the helix angle is substantially 8°. 
   
   
       5 . A helical formation according to  claim 1 , wherein the helical formation is for effecting a rotational flow of fluid within the conduit, in use. 
   
   
       6 . A helical formation according to  claim 1 , wherein the helical formation comprises an elongate member. 
   
   
       7 . A helical formation according to  claim 6 , wherein the elongate member comprises an inwardly extending portion. 
   
   
       8 . A helical formation according to  claim 1 , wherein the helical formation is in the form of an insert adapted to be mounted within the conduit. 
   
   
       9 . A helical formation according to  claim 1 , wherein the helical formation is an integral part of the conduit. 
   
   
       10 . A conduit comprising a helical formation according to  claim 1 . 
   
   
       11 . A conduit according to  claim 10 , wherein the conduit is blood flow tubing. 
   
   
       12 . A conduit according to  claim 11 , wherein the blood flow tubing comprises a graft. 
   
   
       13 . A conduit according to  claim 11 , wherein the blood flow tubing comprises a stent.