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turbinas hidráulicas

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Fig IV.12.- Dimensiones de rodetes Francis y Kaplan<br />

Fig IV.13.- Relación entre ns y la forma del rodete<br />

ηvol Q = θ π D 2 2<br />

4 c2 = θ π D 2 2<br />

4 ϕ2 2 g Hn ⇒ Q = 3,477 θ D 2 2 ϕ 2 Hn<br />

ηvol<br />

El valor de la potencia es: N = 13,33 Q H nη = 46,57 θ D2 2 ϕ2 Hn 3<br />

El valor de ns =<br />

n N<br />

H n 5/4<br />

= n = 84,55 ξ1<br />

D1 Hn =<br />

=<br />

⎛<br />

⎜<br />

⎜<br />

⎝<br />

ηvol<br />

u 2<br />

u1 = ξ 2<br />

ξ 1<br />

ξ1<br />

D 1<br />

84,55 ξ 2<br />

D 2<br />

= ξ2<br />

D 2<br />

η<br />

= D 2<br />

D1<br />

⎞<br />

⎟<br />

⎟<br />

⎠<br />

= 84,55 ξ2 46,57 θ D 2 2 ϕ2 Hn 5/2 η<br />

ηvol<br />

Considerando valores medios del orden de: θ = 0,85, η = 0,85 y ηvol = 0,95, resulta:<br />

ns = 503,2 ξ2 ϕ2 = ξ2 = 0,023 ns 2/3 = 11,57 ns 2/3 ϕ2 ⇒ ϕ2 = 0,007465 ns 2/3<br />

ϕ 2 2 =<br />

c 2 2<br />

2 g H n<br />

= 5,57.10 −5 n s 4 / 3 = f2 (n s )<br />

TF.IV.-61<br />

H n 5/4<br />

D2 Hn = :<br />

= 577 ξ2 θ ϕ 2 η<br />

ηvol

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