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Reaction Turbines. ใช้ Francis turbine อธิบาย Theory Rotodynamic machine. Francis Turbine (Radial Flow). http://www.ltu.se/polopoly_fs/1.4069!7e6edb9d.jpg. Free Vortex Theory. V 1 cos a 1 – U 1 =V r1 cot β 1. B. α 1. V rel1. V 1. V 1 cos a 1. Best Efficiency. V r1. b 1.
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Reaction Turbines ใช้ Francis turbine อธิบาย Theory Rotodynamic machine
Francis Turbine (Radial Flow) http://www.ltu.se/polopoly_fs/1.4069!7e6edb9d.jpg
Free Vortex Theory V1 cos a1 –U1=Vr1 cot β1 B α1 Vrel1 V1 V1 cos a1 Best Efficiency Vr1 b1 R1 R2 V2 U1 V1 T =ρQ (V1 r1 cos a1 – V2 r2 cos) a1 Vr1 cot β1 Vr1 T ≈ ρQV1 r1 cos a1 Vrel1 Q= (2πR1 B) Vr1 = (2πR2 B) Vr2
Example 8.9 Roberson et al A Francis turbine is to be operated at a speed of 600 rpm and with the discharge 4.0 m3/s. If r1 = 0.60 m, β1 = 110o, and the blade height is 10 cm, what should be the guide vane angle α1 for a non-separating flow condition at the runner entrance? V1 cos a1 –U1=Vr1 cot β1 Q= (2πR1 B) Vr1 U1 = ωR1 = 37.7 s α1 = 17.4o
Find Torque T ≈ ρQV1 r1 cos a1 T = 81.2 kN-m Find Power P=Tω P = 5100 kw (Assume no loss ? Friction)
Runners of Axial Flow Turbines http://www.maharashtradirectory.com/Catalogue/images/blowers.gif
Mixed Flow Turbine http://www.adtechnology.co.uk/applications/i/rit_fig2.gif