Elbow provided with guide vanes

An elbow provided with guide vanes wherein the guide vanes are disposed to make the shapes of sub-channels defined thereby similar to each other and the shape of the sub-channels are determined based on the following formulas:

• P.sub.0 =h/{[f/f-r)].sup.m -1} (1)
• a.sub.n =P.sub.0 r[f/f-r)].sup.n ( 2)
• b.sub.n =a.sub.n /f (3)
• h:
• inlet breadth of the elbow
• P.sub.0 :
• overhang length of the guide vanes at the outlet of the elbow
• f:
• enlargement ratio of the elbow expressed by outlet breadth/inlet breadth
• r:
• aspect ratio of the sub-channels (r<f)
• m:
• number of sub-channels
• a.sub.n :
• outlet breadth of n-th sub channel (a.sub.n indicates the radius of curvature of the inner side wail when n=0 and indicates radius of curvature of the outer side wail when n=m)
• b.sub.n :
• inlet breadth of n-th sub-channel.