Page 229 - Fluid Mechanics and Thermodynamics of Turbomachinery

210 Fluid Mechanics, Thermodynamics of Turbomachinery

M r1 = 0.9 a 1
0.4 A C 1
b
1 U
a = 30˚ 0.8 1
1 W
k p 01 01 3 ) a B At A
0.3
1
¦ (M r1 ) = mW 2 /(p 0.8 C 1

· 0.2 0.9

0˚
1
0.1 a = b 1
W U
1 1

0
10 20 30 40 50 60 70 80 At B
Relative flow angle at shroud, b 1 , deg

FIG. 7.4. Variation of mass flow function for the inducer of a centrifugal compressor with
and without guide vanes (
D 1.4). For comparison both velocity triangles are drawn to
scale for M r1 D 0.9 the peak values or curves.

FIG. 7.5. Effect of free-vortex prewhirl vanes upon relative velocity at impeller inlet.