written 6.2 years ago by |
Shaft Power $P_{3}$=11772 kw
Head H=380m
N=750 rpm
overall efficiency, h0=0.86
i) Wheel diameter,D;
Velocity of jet $V_{1}=C\times\sqrt{2gH}$
=0.985$\sqrt{2\times 9.81\times 380}$
=85.05m\s
ku=$\frac{u}{V1}$=0.45
Wheel velocity u=$0.5\times 85.05$
=38.273 m/s
4=$\frac{\pi DN}{60}$
38.273=$\frac{\pi\times D\times 150}{60}$
D=0.975 m
ii) Diameter of jet d
Discharge jet q=$\frac{Q}{h}=\frac{4}{4}=1m^{3}/s$
q=$Area \ of \ jet\times V_{1}$
1=$\frac{\pi}{4}\times {d}^{2}\times 65.14$
d=0.1398 m
iii) Diameter of pipe cline D
let Vm be the Velocity of pipleline
Then Q=$A_{p}\times V_{p}$
$V_{p}=\frac{16}{\pi}\times \frac{1}{D^{2}}$
hf=$\frac{4fLv^{2}_{p}}{D.2g}$
22.5=$0.0045\times 3000\times (\frac{16}{\pi}\times \frac{1}{D^{2}})^{2}\times \frac{1}{D}\times \frac{1}{2\times 9.81}$
$D^{2}$=0.7932
D=0.955 m
Efficiency of transmission through pipe line an nozzles,
n transmission $\frac{Hg-hf}{Hg}$
0.91=$\frac{250-hf}{250}$
h1=22.5m
Net head are turbine
H=Hg-hf
=250-225=22.75m
Velocity of jet $V_{1}=Cv\sqrt{2gH}$
=0.975$\sqrt{2\times 9.81\times 227.5}$=65.14m/s
water power of inputr power to runner
$p_{1}$=k.E of jets
=$\frac{1}{2}mv^{2}_{t}$
=$\frac{1}{2}(PQ)V^{2}_{1}$
$p_{1}=\frac{1}{2}\times 4\times (65.14)^{2}$
=8486.44 $\times 10^{3}w$
$p_{1}$=8486.4 kw
Assuming hydraullic efficiency to be 90 % i.e $h_{4}$=0.9
$p_{3}=n_{n}\times p_{1}$
$0.9\times 8486.4$
=7637.8 kW