ENERGY LOSSES FOR SUBSONIC FLOW Machinery's Handbook, 31st Edition
2786
0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
Angle
6 10 15 20 25 30 35 40 45 50 60
K D
1.1 1.2 1.4 1.6
1.8 2 2.5 3
Do/Di
Fig. 4. Head Loss Coefficient K D , Conical Diffuser
0.6 0.5 0.4 0.3 0.2 0.1 0 1.1 1.2 1.4 1.6 1.8 2 2.2 2.5 3 4 5 10 Di/Do K C
V o (ft/s)
2 8
15 20 30 40
Fig. 5. Head Loss Coefficient K C , Sudden Contraction Gradual Contraction: Gradual contraction, like gradual enlargement, reduces losses by reducing turbulence. Like with gradual enlargement, if the angle is shallow enough, fric tion losses become significant. Included angles greater than 15° avoid this effect. Good performance can be achieved with included angles as high as 60°. To approximate head loss due to gradual contraction, use the following equation and Fig. 6. h l K G v o 2 = where v o is the velocity at the outlet and K G is the loss coefficient. D i / D o is the ratio of the inlet diameter to the outlet diameter. By rounding the exposed edge of the contraction, one can reduce the head loss even further. 2 g ---
Copyright 2020, Industrial Press, Inc.
ebooks.industrialpress.com
Made with FlippingBook - Share PDF online