manaul impact of jet on vanes
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IMPACT OF JET ON VANES
OBJECT:To determine the Co-efficient of impact Jet - Vane combination
by comparing the actual force with the theoretical force for stationary vanes of different shapes, Viz., Hemi-spherical, Flat plate, Inclined Plate.
THEORY:When the jet of water is directed to hit the vane of any
particular shape, the force is exerted on it by the fluid in the opposite direction. The amount of force exerted depends on the diameter of jet, shape of vane, fluid density, and flow rate of water. More importantly, it also depends on whether the vane is moving or stationary. In our present case, we are concerned about the force exerted on the stationary vanes. The following are the theoretical formulae for different shapes of vane, based on flow rate.
FORMULAE FOR DIFFERENT VANES
1) Hemi - spherical
Ft
= (2 A V2 / g)
2) Flat Plate
Ft
= ( A V2 / g)
3) Inclined - Plate
Ft
= ( A V2 / g) x Sin
= 600
1
Where,‘ g ‘ = 9.81 meters / sec2
‘ A ‘ = Area of Jet in m2
‘ ‘ = Density of water = 1000 Kg/m3
‘ V ‘ = Velocity of Jet in m/sec
‘ ‘ = Angle the deflected jet makes with the axis of
the striking jet, in degree = 600
‘ Ft ‘ = The theoretical force acting parallel to the
direction of jet.
‘ Fa ‘ = Actual force developed as indicated by the
analog force indicator.
DESCRIPTION:
It is a closed circuit water re-circulation systems consisting of sump tank,
monoblock pump set, Jet / Vane Chamber, Rota meter for flow rate
measurement, direct reading digital force indicator. The water is drawn from
the sump tank by monoblock centrifugal pump and delivers it vertically to
the nozzle through rotameter.
The rotameter is a direct indicating flow rate instrument which gives the
discharge in LPM (litres per minute) which is determined by the top -
position of the float. The flow control valve is also provided for controlling
the water into the nozzle. The water is issued out of nozzle as jet. The jet is
made to strike the vane, the force of which is tranfered directly to the force
indicator. The force is read in Kgf. The provision is made to change the vane
of different shapes.
2
SPECIFICATIONS:
* Vane shapes : Flat, Hemispherical & Inclined.
* Jet Dia : 4, 5 & 7 mm.
* Measurement : Flow rate of water by direct
Reading Rotameter
: Jet force by direct reading from
digital force indicator
* Type : Re-circulating with sump & jet
Chamber made of stainless
steel.
* Jet Chamber : Fixed with toughened glass
windows with leak proof rubber
gasket.
OPERATING INSTRUCTIONS:
1. Fix the nozzle and the vane of required shape in position and set the
force indicator to show zero
2. Close the front transparent cover tightly.
3. Keep the delivery valve closed and switch ON the pump.
4. Open the delivery valve and adjust the flow rate of water as read on
the Rota meter.
5. Observe the force as indicated on force indicator.
6. Note down the diameter of jet, shape of vane, flow rate, force and
tabulate the results.
3
7. Switch OFF the pump after the experiment is over and close the
delivery valve.
8. Repeat the experiment at different flow rates with same jet and vane.
9. Change the vane and carryout the experiment with different flow
rates.
TABULAR COLUMN:
SL.NO
DIAMETER OF THE JET
‘D’mm
TYPE OF VANE
WATER FLOW RATE
‘Q’Lpm
ACTUAL FORCE
‘Fa’Kg
1. 4
FLAT
INCLINED = 60
HEMI-SPHERE
2. 5
FLAT
INCLINED = 60
HEMI-SPHERE
LIST OF FORMULAE
4
DATA:
* Diameter of the Jets ‘d‘ = 4, 5 & 7mm
* Accleration due to Gravity ‘g‘ = 9.81 m/Sec2
* Density of water ‘w‘ = 1000 Kg/m3
1. Discharge (Q) :
Q Q
D = -------------- m3 / Sec
60 x 1000
Where,
60 & 1000 are conversion factors to m3 / Sec
Q = Rota meter reading in LPM 2. Velocity (V):
QD
V = ----- m/sec A
Where,
A = Area of jet considered,
= d2 / 4 m2
3. Theoretical force (Ft ) :
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a) For Flat Vane:
A V2 F
T1 = ----------- Kg
g
b) For Flat Inclined Vane: A V2
FT2
= ------------x Sin Kg
g Where,
= 600
c) For Hemispherical or Curved Vane:
A V2 FT3 = ---------------- Kg
g
4) Co-efficient of Impact: F
A
CI = --------
FT
Where,
F
A = Actual force, obtained directly from Scale
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TABLE OF CALCULATION:
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Tabular Column(Sample Calculation)
MODELJET DIA
LPM, Q
ACTUAL FORCE in kg, FA
Qd AREA, AVelocity,
VFt1 Ft2 Ft3
Co-Efficien
t of Impact,
CI
HEMI - SPHERICAL
7.00
26.5 0.680 4.42E-04 3.85E-05 11.48
1.034 0.65825.0 0.590 4.17E-04 3.85E-05 10.83 0.920 0.64120.0 0.390 3.33E-04 3.85E-05 8.67 0.589 0.66215.0 0.190 2.50E-04 3.85E-05 6.50 0.331 0.574
FLAT - PLATE 7.00
27.5 0.600 4.58E-04 3.85E-05 11.92 0.557
1.07825.0 0.450 4.17E-04 3.85E-05 10.83 0.460 0.97820.0 0.280 3.33E-04 3.85E-05 8.67 0.294 0.95115.0 0.150 2.50E-04 3.85E-05 6.50 0.166 0.906
INCLINED -PLATE
7.00
26.5 0.400 4.42E-04 3.85E-05 11.48
0.448
0.89325.0 0.380 4.17E-04 3.85E-05 10.83 0.398 0.95420.0 0.250 3.33E-04 3.85E-05 8.67 0.255 0.98015.0 0.130 2.50E-04 3.85E-05 6.50 0.143 0.906
HEMI - SPHERICAL
5.00
18.5 0.540 3.08E-04 1.96E-05 15.71
0.988 0.54715.0 0.360 2.50E-04 1.96E-05 12.74 0.649 0.55410.0 0.150 1.67E-04 1.96E-05 8.49 0.289 0.5205.0 0.030 8.33E-05 1.96E-05 4.25 0.072 0.416
FLAT - PLATE 5.00
19.0 0.490 3.17E-04 1.96E-05 16.14 0.521
0.94115.0 0.310 2.50E-04 1.96E-05 12.74 0.325 0.95510.0 0.100 1.67E-04 1.96E-05 8.49 0.144 0.6935.0 0.030 8.33E-05 1.96E-05 4.25 0.036 0.832
INCLINED -PLATE
5.00
19.0 0.400 3.17E-04 1.96E-05 16.14
0.451
0.88715.0 0.240 2.50E-04 1.96E-05 12.74 0.281 0.85410.0 0.080 1.67E-04 1.96E-05 8.49 0.125 0.6405.0 0.030 8.33E-05 1.96E-05 4.25 0.031 0.960
HEMI - SPHERICAL
4.00
13.5 0.400 2.25E-04 1.26E-05 17.91
0.822 0.48710.0 0.330 1.67E-04 1.26E-05 13.27 0.451 0.7328.0 0.190 1.33E-04 1.26E-05 10.62 0.289 0.6585.0 0.100 8.33E-05 1.26E-05 6.63 0.113 0.887
FLAT - PLATE 4.00
14.0 0.350 2.33E-04 1.26E-05 18.58 0.442
0.79210.0 0.120 1.67E-04 1.26E-05 13.27 0.225 0.5327.5 0.070 1.25E-04 1.26E-05 9.95 0.127 0.5525.0 0.040 8.33E-05 1.26E-05 6.63 0.056 0.710
INCLINED -PLATE
4.00
14.0 0.290 2.33E-04 1.26E-05 18.58
0.383
0.75810.0 0.090 1.67E-04 1.26E-05 13.27 0.195 0.4618.0 0.050 1.33E-04 1.26E-05 10.62 0.125 0.4005.0 0.020 8.33E-05 1.26E-05 6.63 0.049 0.410
GUIDANCE OF CALCULATION:
DATA:
* Diameter of the Jets ‘d‘ = 4, 5 & 7mm
* Acceleration due to Gravity ‘g‘ = 9.81 m/sec2
* Density of water ‘w‘ = 1000 Kg/m3
1. Discharge (Q):
Q Q
D = --------------
60 x 1000
15= -------------- = 2.50 x 10-4 m3 / sec 60 x 1000
Where,
60 & 1000 are conversion factors
to m3 / Sec
Q = Rota meter reading in LPM = 15 LPM
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2. Velocity (V):
QD
V = ----- m/sec A
2.50 x 10-4
-------------- = 12.74 m/sec1.16 x 10-5
Where,
A = Area of jet considered,
= d2 / 4 m2
= x 0.0052 / 4 = 1.16 x 10-5 m2
3. Theoretical force (Ft):
a) For Flat Vane: A V2
FT1
= ----------- Kg
g 1000 x 1.16 x 10-5 x 12.742
= ---------------------------------- 9.81
= 0.325 kg
b) For Flat Inclined Vane: A V2
FT2
= ------------x Sin Kg
g Where,
= 600
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c) For Hemispherical or Curved Vane:
AV2 FT3 = ---------------- Kg
g
4) Co-efficient of Impact :
FA 0.31
CI = -------- = -------- = 0.955
FT
0.325
Where, FA
= Actual force, obtained directly from meter = 0.31 kg
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