RAMMAM INTERMEDIATE STAGE H.E.

PROJECT
INTAKE DESIGN

1 SHAPE OF INTAKE
1.1 As per IS 9761

Total Design Discharge Q 16.5 m3/sec

No. of intakes 1
Dia of intake tunnel (as per Economical diameter of tunnel) D 3.25 m
Height of opening at gate location 3.25
Width of opening at gate location 2.94125 m
Width of opening at gate location provided 2.95 m
Area
Area of intake tunnel 0.905 X d2 9.559 m2
Coeffecient of contraction Cc 0.6
Angle of inclination of penstock
centre line to horizontal Φ 0 Degree
Φ 0 radian
Opening area A A1 15.932 m2
C C Cos 
Velocity at bellmouth V 1.034 m/sec
Velocity at gate location 1.72 m/sec
Height of Opening
 
h1  D1.21tan2   0.0847 2 
1
1
1.1tan h1
 2 cos  2.571 m

 0.791 
h2  D   0.077 tan  
 Cos   h2 2.571 m

Height of Opening = he = h1 + h2 he 5.142 m

Width of Opening required = Opening Area / h e be 3.099 m
Adopted height of opening he 5.15 m
Adopted width of opening be 3.1 m
Opening area provided Ap 15.965 m2 O.K.

2 SUBMERGENCE CALCULATION
2.1 As per IS 9761

v
Froude's number Fr  0.305
gD

Minimum submergence when Froude's no. is > 0.333, h

 0.5  2 Fr
D
Minimum submergence required above C/L of HRT h 3.61 m
Tunnel Invert 1521 m
MDDL 1526.23 m

Minimum submergence when Froude's no. is ≤ 0.333,

h = 1 to 1.5 times he say 1.0*he h 5.14 m
MDDL 1527.77 m

MDDL as per IS code method 1527.77 m

2.2 GORDON
S  kV D
Velocity at intake gate V 5.64 ft/sec
Height at gate location D 10.66 ft
a coefficient, k 0.4
0.3 for symmetrical approach flow, 0.4
for unsymmetrical approach flow
Submergence above the top of gate S 7.37 ft
2.25 m

MDDL as per Gordon's formula 1526.50 m

MDDL to be adopted 1527.77 m

MDDL kept 1525.00 m

 Name of project - PHATA BYONG H.E. PROJECT (UTTARANCHAL)

INTAKE
(As per IS 9761)

Total Design Discharge Q 21.8 m3/sec

No. of intakes 2
Design discharge (with 20 % extra discharge) 13.08 m3/sec Dia of HRT provided
Dia of HRT required (with respect to velocity consideration) D 2.5 m 2.5 m
Area
Circular π/4 X d2 4.909 m2 4.9087385
modified horshoe 0.813375 X d2 5.084 m2
horshoe 0.8293 X d2 5.183 m2
Area of HRT A 4.909 m2
Coeffecient of contraction Cc 0.6
Angle of inclination of penstock
centre line to horizontal Φ 0 Degree
Φ 0 radian
Opening area A A1 8.181 m2
C C Cos 
Velocity in HRT = Q/A V 1.599 m/sec 2.6646357
Height of Opening
 
h1  D1.21tan2   0.0847 2 
1
1 h1
1.1tan 1.978 m
 2 cos 
 0.791 
h2  D   0.077 tan    h2
 Cos  1.978 m

Height of Opening = he = h1 + h2 = he 3.955 m

Width of Opening required = Opening Area / h e be 2.069 m
Adopted height of opening he 3.25 m
Adopted width of opening be 2.95 m
Opening area provided Ap 9.5875 m2 O.K.
 v
Froude's number Fr  0.538063258
gD
As Froude's no. is > 0.333,
h
 0.5  2 Fr
D
Minimum submergence required above C/L of HRT h 3.940 m
Bell Mouth entrance
Vertical transition
The bottom of entrance is placed on the floor. The equation for top contraction is (IS 4880-III, P-7)

0.291 D = 0.94575 m
X Y 1.1 D = 3.575 m
0 0.946
0.5 0.936
1 0.908
1.5 0.858
2 0.784
2.5 0.676
3 0.514
3.5 0.193
3.575 0.000

Height of opening at the start of bell mouth = H 5.142 m

Horizontal transition (IS 9761, P-11)

(0.55 b e)2 2.633 m
X2 Y2
 1 (0.2143 b e)2 0.400 m
 0.55be  2  0.2143be  2
X Y
0 0.632
0.2 0.627
0.4 0.613
0.6 0.587
0.8 0.550
1 0.498
1.2 0.425
1.4 0.320
1.6 0.105
1.6225 0.000
be 2.95 m
a2 1.6225 m
b2 0.632 m
D 3.25 m
 1625 MDDL
MDDL 1625 m

water cushion = 0.4H

Minimum submergence required above C/L of HRT h 3.940 m
1.5 X he 4.875 m
0.9 X H 4.627 m
Submergence provided above C/L of HRT 4.875 m
C/L of intake = MDDL - Min submergence required 1620.125 m

MIN submergence = h
Upper edge of bell mouth = C/L of intake + 0.5 H 1622.696 m 1622.696
Lower edge of bell mouth = C/L of intake - 0.5 H 1617.554 m

Vertical drop below lower edge of bell mouth = 0.3 X H 1.54245 m

Lower level of intake 1616.012 m

1620.125
3.25

5.97874 2.95 1617.554

1616.012
0.632
10 0
0.632
Trash rack 1532

TRASH RACK FRL 1530

Height of trash rack X 11 m
Let the allowable velocity in trash rack v 1 m/sec
Desgin discharge Q 16.5 m3/sec
Area required 16.5 m2 11 m
Assuming 50 % clogging, area required 33 m2
Deducting 20% for area of trash rack bars, clear area required 41.25 m2
Ht of trash rack upto FRL 9 m
Assuming rib depth 0.4 m
No. of vertical panels 3 1521
Clear height upto FRL 8.2 m
Clear width required 5.0305 m
Width provided 5
No of horizontal panels 2
Clear width of single panel 2.500 m
Clear height of single panel 3.267 m
check Height Width
Provide a panel of clear size 3.267 m X 2.5 m
Total clear area of trash rack upto FRL 41 m2
Deducting 20 % for trash rack bars 32.8 m2
Assuming 50 % clogging 16.4 m2
Velocity in trash rack area 1.0061 m/sec

TRASH RACK BARS

Horizontal flats 72 vertical flats

Vertical flats
Spacing between the bars shall be less than the minimum openning between turbine blades
so that there is no blockage and damage to runner blades.(see pump &turbine, USBR)
Thickness of bar t 1.2 cm
Depth of trash bar b 6 cm
Clear spacing between bars l 7 cm
Vertical height of the bars between support h 72 cm
L/t ratio shall be limited to 70 from vibration point of view L/t 60
Differential water head for design of Trash rack 6 m.
Intensity of pressure 0.6 kg/cm2
load on the bar 302.4 kg
B.M. = wL/10 2177.28 kg-cm
Allowable stress in steel f y 1650 kg/cm2
failure stress = fy*(1.23 - 0.0153*L/t) = 514.80 kg/cm2
safe stress =0.6 *failure stress 308.88 kg/cm2
Z required = B.M./ safe stress Z req 7.05 cm3
Z provided = t*w2/6 Z prov 9.8 cm3
safe

Horizontal flats
Panel clear size 3.267 m X 2.5 m
Height Width (B)
Total load on horizontal flat = w X l X B W 1050 kg
Maximum bending moment = W B / 8 M 32812.5 kg-cm
Z required = M / fy 19.89 cm3
Provide ISMC 200
Z provided 26.3 cm3 O.K.
 RAMMAM INTERMEDIATE STAGE H.E. PROJECT
INTAKE DESIGN

1 SHAPE OF INTAKE
1.1 As per IS 9761

Total Design Discharge Q m3/sec 16.5

No. of intakes 1
Dia of intake tunnel (as per Economical diameter of tunnel) D m 3.25
Height of opening at gate location 3.25
Width of opening at gate location m 2.94
Width of opening at gate location provided m 2.95
Area
Area of intake tunnel 0.905 X d2 m2 9.559
Coeffecient of contraction Cc 0.6
Angle of inclination of penstock
centre line to horizontal Φ Degree 0
Φ radian 0
Opening area A A1 m2 15.932
C C Cos 
Velocity at bellmouth V m/sec 1.034
Velocity at gate location m/sec 1.72
Height of Opening
 
h1  D1.21tan2   0.0847 2 
1
1
1.1tan h1
 2 cos  m 2.571

 0.791 
h2  D   0.077 tan  
 Cos   h2 2.571
m

Height of Opening = he = h1 + h2 he m 5.142

Width of Opening required = Opening Area / h e be m 3.099
Adopted height of opening he m 5.15
Adopted width of opening be m 3.1
Opening area provided Ap m2 15.965
O.K.
2 SUBMERGENCE CALCULATION
2.1 As per IS 9761
v
Froude's number Fr  0.305
gD

Minimum submergence when Froude's no. is > 0.333, h

 0.5  2 Fr
D
Minimum submergence required above C/L of HRT h m 3.61
Tunnel Invert m 1521
MDDL m 1526.23

Minimum submergence when Froude's no. is ≤ 0.333,

 h = 1 to 1.5 times he say 1.0*he h m 5.14
MDDL m 1527.77

MDDL as per IS code method m 1527.77

2.2 GORDON
S  kV D
Velocity at intake gate V ft/sec 5.64
Height at gate location D ft 10.66
a coefficient, k 0.4
0.3 for symmetrical approach flow, 0.4
for unsymmetrical approach flow
Submergence above the top of gate S ft 7.37
m 2.25

MDDL as per Gordon's formula m 1526.50

MDDL to be adopted m 1527.77

MDDL kept m 1528.00

Bell Mouth entrance

Vertical transition
The bottom of entrance is placed on the floor. The equation for top contraction is (IS 4880-III, P-7)
0.291 D = m 0.94575
1.1 D = m 3.575
X Y
0 0.946
0.5 0.936
1 0.908
1.5 0.858
2 0.784
2.5 0.676
3 0.514
3.5 0.193
3.575 0.000

Height of opening at the start of bell mouth = H m 5.142

Horizontal transition (IS 9761, P-11)

2 2 (0.55 b e)2 m 2.633
X Y
 1 (0.2143 b e)2 m 0.400
 0.55be   0.2143be  2
2

X Y
0 0.632
0.2 0.627
0.4 0.613
0.6 0.587
0.8 0.550
1 0.498
1.2 0.425
1.4 0.320
1.6 0.105
 1.6225 0.000

Width of opening at the start of bellmouth B m 4.214

TRASH RACK
Height of trash rack X m 14
Let the allowable velocity in trash rack v m/sec 1
Desgin discharge Q m3/sec 16.5
Area required m2 16.5
Assuming 50 % clogging, area required m2 33
Deducting 20% for area of trash rack bars, clear area required m2 41.25
Ht of trash rack upto FRL m 12
Assuming rib depth m 0.5
No. of vertical panels 3
Clear height upto FRL m 11
Clear width required m 3.7500
Width provided 5
No of horizontal panels 2
Clear width of single panel m 2.500
Clear height of single panel m 4.167

check Height Width

Provide a panel of clear size 4.167 m X m 2.5
Total clear area of trash rack upto FRL m2 55
Deducting 20 % for trash rack bars m2 44
Assuming 50 % clogging m2 22
Velocity in trash rack area m/sec 0.7500

TRASH RACK BARS

Vertical flats
Spacing between the bars shall be less than the minimum openning between turbine blades
so that there is no blockage and damage to runner blades.(see pump &turbine, USBR)
Thickness of bar t cm 1.2
Depth of trash bar b cm 6
Clear spacing between bars l cm 7
Vertical height of the bars between support h cm 72
L/t ratio shall be limited to 70 from vibration point of view L/t 60
Differential water head for design of Trash rack m. 6
Intensity of pressure kg/cm2 0.6
load on the bar kg 302.4
B.M. = wL/10 kg-cm 2177
Allowable stress in steel f y kg/cm2 1650
failure stress = fy*(1.23 - 0.0153*L/t) = kg/cm2 514.80
safe stress =0.6 *failure stress kg/cm2 308.88
Z required = B.M./ safe stress Z req cm3 7.05
Z provided = t*w /62 Z prov cm3 9.8
safe

Horizontal flats
Panel clear size 4.167 m X 2.5 m
Height Width (B)
Total load on horizontal flat = w X l X B W kg 1050
Maximum bending moment = W B / 8 M kg-cm 32812.5
Z required = M / fy cm3 19.89
Provide ISMC 200
Z provided cm3 26.3
O.K.
 16.5
1
3.25
2.5
3.25
3.25

9.559
0.6

0
0
15.932

1.006
2.03

1.978

1.978

3.955
4.028
4
4.1
16.4
O.K.

0.410

3.30
1521
1525.55
 3.96
1526.21

1525.55

6.66
8.20
0.4

7.63
2.33

1525.83

1525.83

1526.00

0.7275
2.75
X Y
0 0.728
0.5 0.715
1 0.678
1.5 0.610
2 0.499
2.5 0.303
2.75 0.000

3.955

3.195
0.485

X Y
0 0.696
0.2 0.692
0.4 0.679
0.6 0.656
0.8 0.623
1 0.577
1.2 0.516
1.4 0.433
1.6 0.311
 1.6225 0.292
1.7875 0.000

4.643

Trash rack 1532

FRL 1530

14 m

1518

72 vertical flats

7
 Name of project - PHATA BYONG H.E. PROJECT (UTTARANCHAL)

INTAKE
(As per IS 9761)

Total Design Discharge Q 21.8 m3/sec

No. of intakes 2
Design discharge (with 20 % extra discharge) 13.08 m3/sec
Dia of HRT required (with respect to velocity consideration) D 2.5 m
Area
Circular π/4 X d2 4.909 m2
modified horshoe 0.813375 X d2 5.084 m2
horshoe 0.8293 X d2 5.183 m2
Area of HRT A 4.909 m2
Coeffecient of contraction Cc 0.6
Angle of inclination of penstock
centre line to horizontal Φ 0 Degree
Φ 0 radian
Opening area A A1 8.181 m2
C C Cos 
Velocity in HRT = Q/A V 1.599 m/sec
Height of Opening
 
h1  D1.21tan2   0.0847 2 
1
1 h1
1.1tan 1.978 m
 2 cos 
 0.791 
h2  D   0.077 tan    h2
 Cos  1.978 m

Height of Opening = he = h1 + h2 = he 3.955 m

Width of Opening required = Opening Area / h e be 2.069 m
Adopted height of opening he 3.25 m
Adopted width of opening be 2.95 m
Opening area provided Ap 9.5875 m2
 v
Froude's number Fr  0.538063258
gD
As Froude's no. is > 0.333,
h
 0.5  2 Fr
D
Minimum submergence required above C/L of HRT h 3.940 m

Bell Mouth entrance

Vertical transition
The bottom of entrance is placed on the floor. The equation for top contraction is (IS 4880-III, P-7)

0.291 D = 0.7275 m
X Y 1.1 D = 2.75 m
0 0.728
0.5 0.715
1 0.678
1.5 0.610
2 0.499
2.5 0.303
2.75 0.000

Height of opening at the start of bell mouth = H 3.955 m

Horizontal transition (IS 9761, P-11)

(0.55 b e)2 5.085 m
X2 Y2
 1 (0.2143 b e)2 0.772 m
 0.55be   0.2143be  2
2

X Y
0 0.879
0.2 0.875
 0.4 0.865
0.6 0.847
0.8 0.821
1 0.788
1.2 0.744
1.4 0.689
1.6 0.619
1.6225 0.610

be 2.95 m
a2 1.6225 m
b2 0.632 m
D 3.25 m

MDDL 1625 m
Minimum submergence required above C/L of HRT h 3.940 m
1.5 X he 4.875 m
0.9 X H 3.560 m
Submergence provided above C/L of HRT 4.875 m
C/L of intake = MDDL - Min submergence required 1620.125 m
Upper edge of bell mouth = C/L of intake + 0.5 H 1622.103 m
Lower edge of bell mouth = C/L of intake - 0.5 H 1618.148 m

Vertical drop below lower edge of bell mouth = 0.3 X H 1.1865 m

Lower level of intake 1616.961 m

6.96452 2.95

0.879

0.879

TRASH RACK
Height of trash rack X 11 m
Let the allowable velocity in trash rack v 1 m/sec
Desgin discharge Q 16.5 m3/sec
Area required 16.5 m2
Assuming 50 % clogging, area required 33 m2
Deducting 20% for area of trash rack bars, clear area required 41.25 m2
Ht of trash rack upto FRL 9 m
Assuming rib depth 0.4 m
No. of vertical panels 3
Clear height upto FRL 8.2 m
Clear width required 5.0305 m
Width provided 5
No of horizontal panels 2
Clear width of single panel 2.500 m
Clear height of single panel 3.267 m

check Height Width

Provide a panel of clear size 3.267 m X 2.5 m
Total clear area of trash rack upto FRL 41 m2
Deducting 20 % for trash rack bars 32.8 m2
Assuming 50 % clogging 16.4 m2
Velocity in trash rack area 1.0061 m/sec

TRASH RACK BARS

Horizontal flats 72 vertical flats

Vertical flats
Spacing between the bars shall be less than the minimum openning between turbine blades
so that there is no blockage and damage to runner blades.(see pump &turbine, USBR)
Thickness of bar t 1.2 cm
Depth of trash bar b 6 cm
Clear spacing between bars l 7 cm
Vertical height of the bars between support h 72 cm
L/t ratio shall be limited to 70 from vibration point of view L/t 60
Differential water head for design of Trash rack 6 m.
Intensity of pressure 0.6 kg/cm2
load on the bar 302.4 kg
B.M. = wL/10 2177.28 kg-cm
Allowable stress in steel f y 1650 kg/cm2
failure stress = fy*(1.23 - 0.0153*L/t) = 514.80 kg/cm2
safe stress =0.6 *failure stress 308.88 kg/cm2
Z required = B.M./ safe stress Z req 7.05 cm3
Z provided = t*w2/6 Z prov 9.8 cm3
safe

Horizontal flats
Panel clear size 3.267 m X 2.5 m
Height Width (B)
Total load on horizontal flat = w X l X B W 1050 kg
Maximum bending moment = W B / 8 M 32812.5 kg-cm
Z required = M / fy 19.89 cm3
Provide ISMC 200
Z provided 26.3 cm3
 Dia of HRT provided
2.5 m

4.9087385

2.6646357

O.K.
 1625 MDDL
water cushion = 0.4H
MIN submergence = h

1622.103

1620.125
3.25

1618.148
1616.961

10 0

Trash rack 1532

FRL 1530

11 m
1521
O.K.
 RAMMAM INTERMEDIATE STAGE H.E. PROJECT
INTAKE DESIGN

1 SHAPE OF INTAKE
1.1 As per IS 9761

Total Design Discharge Q m3/sec 16.26

No. of intakes 1
Dia of intake tunnel (as per Economical diameter of tunnel) D m 3.25
Height of opening at gate location 3.25
Width of opening at gate location m 2.94
Width of opening at gate location provided m 2.95
Area
Area of intake tunnel 0.905 X d2 m2 9.559
Coeffecient of contraction Cc 0.6
Angle of inclination of penstock
centre line to horizontal Φ Degree 0
Φ radian 0
Opening area A A1 m2 15.932
C C Cos 
Velocity at bellmouth V m/sec 1.018
Velocity at gate location m/sec 1.70
Height of Opening
 
h1  D1.21tan2   0.0847 2 
1
1
1.1tan h1
 2 cos  m 2.571

 0.791 
h2  D   0.077 tan  
 Cos   h2 2.571
m

Height of Opening = he = h1 + h2 he m 5.142

Width of Opening required = Opening Area / h e be m 3.099
Adopted height of opening he m 5.15
Adopted width of opening be m 3.1
Opening area provided Ap m2 15.965
O.K.
2 SUBMERGENCE CALCULATION
2.1 As per IS 9761
v
Froude's number Fr  0.300
gD

Minimum submergence when Froude's no. is > 0.333, h

 0.5  2 Fr
D
Minimum submergence required above C/L of HRT h m 3.58
Tunnel Invert m 1521
 MDDL m 1526.20

Minimum submergence when Froude's no. is ≤ 0.333,

h = 1 to 1.5 times he say 1.0*he h m 5.14
MDDL m 1527.77

MDDL as per IS code method m 1527.77

2.2 GORDON
S  kV D
Velocity at intake gate V ft/sec 5.56
Height at gate location D ft 10.66
a coefficient, k 0.4
0.3 for symmetrical approach flow, 0.4
for unsymmetrical approach flow
Submergence above the top of gate S ft 7.26
m 2.21

MDDL as per Gordon's formula m 1526.46

MDDL to be adopted m 1527.77

MDDL kept m 1528.00

Bell Mouth entrance

Vertical transition
The bottom of entrance is placed on the floor. The equation for top contraction is (IS 4880-III, P-7)
0.291 D = m 0.94575
1.1 D = m 3.575
X Y
0 0.946
0.5 0.936
1 0.908
1.5 0.858
2 0.784
2.5 0.676
3 0.514
3.5 0.193
3.575 0.000

Height of opening at the start of bell mouth = H m 5.142

Horizontal transition (IS 9761, P-11)

(0.55 b e)2 m 2.633
X2 Y2
 1 (0.2143 b e)2 m 0.400
 0.55be   0.2143be  2
2

X Y
0 0.632
0.2 0.627
 0.4 0.613
0.6 0.587
0.8 0.550
1 0.498
1.2 0.425
1.4 0.320
1.6 0.105
1.6225 0.000

Width of opening at the start of bellmouth B m 4.214

TRASH RACK
Height of trash rack X m 11
Let the allowable velocity in trash rack v m/sec 1
Desgin discharge Q m3/sec 16.26
Area required m2 16.26
Assuming 50 % clogging, area required m2 32.52
Deducting 20% for area of trash rack bars, clear area required m2 40.65
Ht of trash rack upto FRL m 9
Assuming rib depth m 0.4
No. of vertical panels 3
Clear height upto FRL m 8.2
Clear width required m 4.9573
Width provided 5
No of horizontal panels 2
Clear width of single panel m 2.500
Clear height of single panel m 3.267

check Height Width

Provide a panel of clear size 3.267 m X m 2.5
Total clear area of trash rack upto FRL m2 41
Deducting 20 % for trash rack bars m2 32.8
Assuming 50 % clogging m2 16.4
Velocity in trash rack area m/sec 0.9915

TRASH RACK BARS

Vertical flats
Spacing between the bars shall be less than the minimum openning between turbine blades
so that there is no blockage and damage to runner blades.(see pump &turbine, USBR)
Thickness of bar t cm 1.2
Depth of trash bar b cm 6
Clear spacing between bars l cm 7
Vertical height of the bars between support h cm 72
L/t ratio shall be limited to 70 from vibration point of view L/t 60
Differential water head for design of Trash rack m. 6
Intensity of pressure kg/cm2 0.6
load on the bar kg 302.4
B.M. = wL/10 kg-cm 2177
Allowable stress in steel f y kg/cm2 1650
failure stress = fy*(1.23 - 0.0153*L/t) = kg/cm2 514.80
safe stress =0.6 *failure stress kg/cm2 308.88
Z required = B.M./ safe stress Z req cm3 7.05
Z provided = t*w2/6 Z prov cm3 9.8
safe

Horizontal flats
Panel clear size 3.267 m X 2.5 m
Height Width (B)
Total load on horizontal flat = w X l X B W kg 1050
Maximum bending moment = W B / 8 M kg-cm 32812.5
Z required = M / fy cm3 19.89
Provide ISMC 200
Z provided cm3 26.3
O.K.
16.26
1
3.25
2.5
3.25
3.25

9.559
0.6

0
0
15.932

0.991
2.00

1.978

1.978

3.955
4.028
4
4.1
16.4
O.K.

0.404

3.27
1521
1525.52

3.96
1526.21

1525.52

6.56
8.20
0.4

7.52
2.29

1525.79

1525.79

1526.00

0.7275
2.75
X Y
0 0.728
0.5 0.715
1 0.678
1.5 0.610
2 0.499
2.5 0.303
2.75 0.000

3.955

3.195
0.485

X Y
0 0.696
0.2 0.692
 0.4 0.679
0.6 0.656
0.8 0.623
1 0.577
1.2 0.516
1.4 0.433
1.6 0.311
1.6225 0.292
1.7875 0.000

4.643

Trash rack 1532

FRL 1530

11 m

1521

72 vertical flats

7
 RAMMAM INTERMEDIATE STAGE H.E. PROJECT
INTAKE DESIGN

1 SHAPE OF INTAKE
1.1 As per IS 9761

Total Design Discharge Q m3/sec 16.5

No. of intakes 1
Dia of intake tunnel (as per Economical diameter of tunnel) D m 3.25
Height of opening at gate location m 2.5
Width of opening at gate location m 3.25
Width of opening at gate location provided m 3.25
Area
Area of intake tunnel 0.905 X d2 m2 9.559
Coeffecient of contraction Cc 0.6
Angle of inclination of penstock
centre line to horizontal Φ Degree 0
Φ radian 0
Opening area A A1 m2 15.932
C C Cos 
Velocity at bellmouth V m/sec 1.006
Velocity at gate location m/sec 2.03
Height of Opening
 
h1  D1.21tan2   0.0847 2 
1
1
1.1tan h1
 2 cos  m 1.978

 0.791 
h2  D   0.077 tan  
 Cos   h2 1.978
m

Height of Opening = he = h1 + h2 he m 3.955

Width of Opening required = Opening Area / h e be m 4.028
Adopted height of opening he m 4
Adopted width of opening be m 4.1
Opening area provided Ap m2 16.4
O.K.
2 SUBMERGENCE CALCULATION
2.1 As per IS 9761
v
Froude's number Fr  0.410
gD

Minimum submergence when Froude's no. is > 0.333, h

 0.5  2 Fr
D
Minimum submergence required above C/L of HRT h m 3.30
Tunnel Invert m 1521
MDDL m 1525.55

Minimum submergence when Froude's no. is ≤ 0.333,

 h = 1 to 1.5 times he say 1.0*he h m 3.96
MDDL m 1526.21

MDDL as per IS code method m 1525.55

2.2 GORDON
S  kV D
Velocity at intake gate V ft/sec 6.66
Height at gate location D ft 8.20
a coefficient, 0.3 for symmetrical approach flow,
0.4 for unsymmetrical approach k 0.4
flow
Submergence above the top of gate S ft 7.63
m 2.33

MDDL as per Gordon's formula m 1525.83

MDDL to be adopted m 1525.83

MDDL kept m 1526.00

Bell Mouth entrance

Vertical transition
0.291 D = m 0.7275
1.1 D = m 2.75
X Y
0 0.728
0.5 0.715
1 0.678
1.5 0.610
2 0.499
2.5 0.303
2.75 0.000

Height of opening at the start of bell mouth H = m 3.955

~ 4.0
Horizontal transition (IS 9761, P-11)
(0.55 b e)2 = m 3.195
X2 Y2
 1 (0.2143 b e)2 = m 0.485
 0.55be  2  0.2143be  2
X Y
0 0.696
0.2 0.692
0.4 0.679
0.6 0.656
0.8 0.623
1 0.577
1.2 0.516
1.4 0.433
1.6 0.311
1.6225 0.292
1.7875 0.000
 Width of opening at the start of bellmouth B = m 4.64
~ 4.65

TRASH RACK
Height of trash rack X m 14
Let the allowable velocity in trash rack v m/sec 1
Desgin discharge Q m3/sec 16.5
Area required m2 16.5
Assuming 50 % clogging, area required m2 33
Deducting 20% for area of trash rack bars, clear area required m2 41.25
Ht of trash rack upto FRL m 12
Assuming rib depth m 0.5
No. of vertical panels 4
Clear height upto FRL m 10.5
Clear width required m 3.9286
Width provided 5
No of horizontal panels 2
Clear width of single panel m 2.500
Clear height of single panel m 3.000

check Height Width

Provide a panel of clear size 3.000 m X m 2.5
Total clear area of trash rack upto FRL m2 52.5
Deducting 20 % for trash rack bars m2 42
Assuming 50 % clogging m2 21
Velocity in trash rack area m/sec 0.7857

TRASH RACK BARS

Vertical flats
Spacing between the bars shall be less than the minimum openning between turbine blades
so that there is no blockage and damage to runner blades.(see pump &turbine, USBR)
Thickness of bar t cm 1.2
Depth of trash bar b cm 6
Clear spacing between bars l cm 7
Vertical height of the bars between support h cm 72
L/t ratio shall be limited to 70 from vibration point of view L/t 60
Differential water head for design of Trash rack m. 6
Intensity of pressure kg/cm2 0.6
load on the bar kg 302.4
B.M. = wL/10 kg-cm 2177
Allowable stress in steel f y kg/cm 2
1650
failure stress = fy*(1.23 - 0.0153*L/t) = kg/cm 2
514.80
safe stress =0.6 *failure stress kg/cm2 308.88
Z required = B.M./ safe stress Z req cm 3
7.05
Z provided = t*w2/6 Z prov cm 3
9.8
safe

Horizontal flats
Panel clear size 3.000 m X 2.5 m
Height Width (B)
Total load on horizontal flat = w X l X B W kg 1050
Maximum bending moment = W B / 8 M kg-cm 32812.5
Z required = M / fy cm3 19.89
Provide ISMC 200
Z provided cm3 26.3
O.K.
Trash rack 1532

FRL 1530

14 m

1518

72 vertical flats

7
 RAMMAM INTERMEDIATE STAGE H.E. PROJECT
INTAKE DESIGN

1 SHAPE OF INTAKE
1.1 As per IS 9761

Total Design Discharge Q m3/sec 16.5

No. of intakes 1
Dia of intake tunnel (as per Economical diameter of tunnel) D m 3.25
Height of opening at gate location m 2.5
Width of opening at gate location m 3.25
Width of opening at gate location provided m 3.25
Area
Area of intake tunnel 0.905 X d2 m2 8.125
Coeffecient of contraction Cc 0.6
Angle of inclination of penstock
centre line to horizontal Φ Degree 0
Φ radian 0
Opening area A A1 m2 13.542
C C Cos 
Velocity at bellmouth V m/sec 1.006
Velocity at gate location m/sec 2.03
Height of Opening
 
h1  D1.21tan2   0.0847 2 
1
1
1.1tan h1
 2 cos  m 1.978

 0.791 
h2  D   0.077 tan  
 Cos   h2 1.978
m

Height of Opening = he = h1 + h2 he m 3.955

Width of Opening required = Opening Area / h e be m 3.424
Adopted height of opening he m 4
Adopted width of opening be m 4.1
Opening area provided Ap m2 16.4
O.K.
2 SUBMERGENCE CALCULATION
2.1 As per IS 9761
v
Froude's number Fr  0.410
gD

Minimum submergence when Froude's no. is > 0.333, h

 0.5  2 Fr
D
Minimum submergence required above C/L of HRT h m 3.30
Tunnel Invert m 1521
MDDL m 1525.55

Minimum submergence when Froude's no. is ≤ 0.333,

 h = 1 to 1.5 times he say 1.0*he h m 3.96
MDDL m 1526.21

MDDL as per IS code method m 1525.55

2.2 GORDON
S  kV D
Velocity at intake gate V ft/sec 6.66
Height at gate location D ft 8.20
a coefficient, 0.3 for symmetrical approach flow,
0.4 for unsymmetrical approach k 0.4
flow
Submergence above the top of gate S ft 7.63
m 2.33

MDDL as per Gordon's formula m 1525.83

MDDL to be adopted m 1525.83

MDDL kept m 1526.00

Bell Mouth entrance

Vertical transition
0.291 D = m 0.7275
1.1 D = m 2.75
X Y
0 0.728
0.5 0.715
1 0.678
1.5 0.610
2 0.499
2.5 0.303
2.75 0.000

Height of opening at the start of bell mouth H = m 3.955

~ 4.0
Horizontal transition (IS 9761, P-11)
(0.55 b e)2 = m 3.195
X2 Y2
 1 (0.2143 b e)2 = m 0.485
 0.55be  2  0.2143be  2
X Y
0 0.696
0.2 0.692
0.4 0.679
0.6 0.656
0.8 0.623
1 0.577
1.2 0.516
1.4 0.433
1.6 0.311
1.6225 0.292
1.7875 0.000
 Width of opening at the start of bellmouth B = m 4.64
~ 4.65

TRASH RACK
Height of trash rack X m 14
Let the allowable velocity in trash rack v m/sec 1
Desgin discharge Q m3/sec 16.5
Area required m2 16.5
Assuming 50 % clogging, area required m2 33
Deducting 20% for area of trash rack bars, clear area required m2 41.25
Ht of trash rack upto FRL m 12
Assuming rib depth m 0.5
No. of vertical panels 4
Clear height upto FRL m 10.5
Clear width required m 3.9286
Width provided 5
No of horizontal panels 2
Clear width of single panel m 2.500
Clear height of single panel m 3.000

check Height Width

Provide a panel of clear size 3.000 m X m 2.5
Total clear area of trash rack upto FRL m2 52.5
Deducting 20 % for trash rack bars m2 42
Assuming 50 % clogging m2 21
Velocity in trash rack area m/sec 0.7857

TRASH RACK BARS

Vertical flats
Spacing between the bars shall be less than the minimum openning between turbine blades
so that there is no blockage and damage to runner blades.(see pump &turbine, USBR)
Thickness of bar t cm 1.2
Depth of trash bar b cm 6
Clear spacing between bars l cm 7
Vertical height of the bars between support h cm 72
L/t ratio shall be limited to 70 from vibration point of view L/t 60
Differential water head for design of Trash rack m. 6
Intensity of pressure kg/cm2 0.6
load on the bar kg 302.4
B.M. = wL/10 kg-cm 2177
Allowable stress in steel f y kg/cm 2
1650
failure stress = fy*(1.23 - 0.0153*L/t) = kg/cm 2
514.80
safe stress =0.6 *failure stress kg/cm2 308.88
Z required = B.M./ safe stress Z req cm 3
7.05
Z provided = t*w2/6 Z prov cm 3
9.8
safe

Horizontal flats
Panel clear size 3.000 m X 2.5 m
Height Width (B)
Total load on horizontal flat = w X l X B W kg 1050
Maximum bending moment = W B / 8 M kg-cm 32812.5
Z required = M / fy cm3 19.89
Provide ISMC 200
Z provided cm3 26.3
O.K.
Trash rack 1532

FRL 1530

14 m

1518

72 vertical flats

7
Area of Air Vent

Design Discharge Q m3/s 72.38

Diameter of Penstock d mm 4300

Thickness of Penstock t mm 20

FOS of collapse of power conduit S 5

Coefficient of discharge c 0.5

Conversion factor k 0.305

Area of Air Vent F m2 0.127

Dia of Air vent Required m 0.401