fluids lab presentation

7/29/2019 fluids lab presentation

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Group 2:

Fabiola CampoblancoJoshua Brown

Lane Hargroder

Jonathan Lambes

Javier Sanchez

Department of Civil and Environmental EngineeringLouisiana State University

Summer 2013CE 2250

Fluid Mechanics Laboratory


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Introduction Newtons Second Law

Applied to building

structures


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Introduction Turbines

convert the force from

moving fluids, which striketheir blades, into mechanicalenergy.

Pumps

convert mechanical forces intofluid momentum.


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Introduction Newtons second law

important when it comes to determining fluid forces

usually easier to monitor a selected area than followindividual fluid particles.

Control Volume analysis Newtons second law is converted to the Conservation of

Linear Momentum Equation for Control Volumes


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Objectives Fluid Forces Laboratory

Find the forces produced by a jet of water sprayingagainst a flat vane and a cupped vane

Compare experimental results to theoretical values

Calculated using the Conservation of Linear MomentumEquation


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Newtons 2

nd

Law The acceleration of a body is directly proportional to

the net force acting on the body, and inverselyproportional to its mass.

Thus, F=ma


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Conservation of Momentum

Assumptions The jet is a free jet open to the atmosphere

Pressure is atmospheric

The vane is smooth, and there is no friction betweenthe jet and the vane

The jet velocity is uniform throughout its path

The fluid is incompressible


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Conservation of Momentum By setting certain assumptions in place, one can use

the Conservation of Momentum with integral controlvolume analysis to relate fluid flows and velocitieswith forces.

F=moutVout- minVin Where m=mass flow rate, and V=velocity


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Force Equation Derivation Noting that the mass flow rate equals Q, the pressure

and shear forces cancel leaving only the force actingthrough the vertical nozzle in the y direction

Thus,

F=Fy=Q(Vout-Vin)y


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Flat Vane In the case of a flat vane, the outflow velocity Vout is

related to the inflow velocity through the angle , sincethe outflow velocity is only in the x direction there isno y component leaving

F=QVin(1-cos)

For a flat vane =90o

, reducing the equation to:F=QVin


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Cupped Vane In the case for a cupped vane the outflow velocities are

in both the x and y directions. If =135o

F=QVin(1-cos(135o

))F=1.7071QVin


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Velocity Decrease Due to Gravity The relationship between the jet velocity at the nozzle

and the vane is derived from Bernoullis Equation

V

2

in=V

2

in-2gd

Where,

g = gravity = 9.81 m/s2

d = distance from the nozzle to the vane surface


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Materials and Methods Cussons P6233 Impact of Jets Apparatus

Cussons P6100 Hydraulics Bench

Flat and Cupped Target Vanes Brass Weights

Volume Meter


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Main Apparatus Cussons P6233 Impact of Jets Apparatus

Cussons P6100 Hydraulics Bench


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Target Vanes Flat

Cupped


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Brass Weights


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Volume Meter


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Step 1 Position the weight carrier on the weight platform.

Measure the distance from exit of the nozzle to the

surface of the vane. Move the pointer flag so it alignswith the weight platform to provide initialequilibrium conditions.

Add the initial 520 grams of weight to the platform.


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Step 2 Now start the pump and establish the water flow by

steadily opening the regulating valve until it is fullyopen and the pump is at maximum. The impact of

the jet will deflect the vane.


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Step 3 Place additional weights until the weight platform isagain floating in mid position.

Record the weight.

Then measure the flow rate using the volume meter torecord the water volume and a stopwatch to record thetime. To keep this measurement accurate, wait until the

volume has reached 50 Liters and then record the time.


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Step 4 Reduce the weight on the carrier and maintain the

equilibrium position by regulating the flow rate.

Record the weight on the carrier, water volume, and

time it takes to reach that water volume for eachdecrease in weight.

Now close the bench regulating valve and switch offthe pump. Allow the apparatus to drain.


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Step 5 Replace the Flat Vane with the Cupped Vane andrepeat the test.


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Data: Flat VaneNozzle Diameter Size

(mm) 8Nozzle Area (m2) 5.027E-05

Height (mm) 45Initial Weight (g) 200

Trial 1 2 3 4 5 6Weight (g) 550 500 450 400 350 300

Volume Filled (l) 50 50 50 50 50 50Time Required (s) 103 104.9 112 119 127.3 137Flow Rate (L/min) 29.13 28.60 26.79 25.21 23.57 21.90Flow Rate (m3/s) 4.85E-04 4.77E-04 4.46E-04 4.20E-04 3.93E-04 3.65E-04

Nozzle Velocity (m/s) 9.66 9.48 8.88 8.36 7.81 7.26Inflow Velocity (m/s) 9.61 9.44 8.83 8.31 7.76 7.20Impulse Momentum

(N) 4.67 4.50 3.94 3.49 3.05 2.63Theoretical Force (N) 4.67 4.50 3.94 3.49 3.05 2.63

Experimental Force (N) 5.40 4.91 4.41 3.92 3.43 2.94Experimental Error (%) 15.64 9.06 11.97 12.44 12.69 12.00

Ratio 1.16 1.09 1.12 1.12 1.13 1.12


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Data: Cupped VaneNozzle Diameter Size

(mm) 8Nozzle Area (m2) 5.027E-05

Height (mm) 38Initial Weight (g) 200

Trial 1 2 3 4 5 6Weight (g) 770 700 630 560 490 420

Volume Filled (l) 50 50 50 50 50 50Time Required (s) 102 104 110 124 128 134Flow Rate (L/min) 29.41 28.85 27.27 24.19 23.44 22.39Flow Rate (m3/s) 4.90E-04 4.81E-04 4.55E-04 4.03E-04 3.91E-04 3.73E-04

Nozzle Velocity (m/s) 9.75 9.56 9.04 8.02 7.77 7.42Inflow Velocity (m/s) 9.71 9.53 9.00 7.98 7.72 7.37Impulse Momentum

(N) 4.76 4.58 4.09 3.22 3.02 2.75Theoretical Force (N) 8.13 7.82 6.98 5.49 5.15 4.70

Experimental Force (N) 7.55 6.87 6.18 5.49 4.81 4.12Experimental Error (%) 7.1 12.2 11.5 0.1 6.7 12.3

Ratio 0.93 0.88 0.88 1.00 0.93 0.88


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Results: Flat Vane

y = tan(41.137o)x + 0.0699

2.00

2.50

3.00

3.50

4.00

4.50

5.00

2 3 4 5 6

T

heoreticalForce

(N)

Experimental Force (N)


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Results: Cupped Vane

y = tan(47.964o)x - 0.0966

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5

9

4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9

T

heoreticalForce

(N)

Experimental Force (N)


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Results: Flat Vane

1.08

1.09

1.10

1.11

1.12

1.13

1.14

1.15

1.16

1.17

0.0003 0.00032 0.00034 0.00036 0.00038 0.0004 0.00042 0.00044 0.00046 0.00048 0.0005

ForceRatio

Flow Rate (m3/s)


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0.86

0.88

0.90

0.92

0.94

0.96

0.98

1.00

1.02

0.0003 0.00032 0.00034 0.00036 0.00038 0.0004 0.00042 0.00044 0.00046 0.00048 0.0005

ForceRatio

Flow Rate (m3/s)


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Results: Flat Vane

y = 1.1236x

2.50

3.00

3.50

4.00

4.50

5.00

5.50

6.00

2.50 3.00 3.50 4.00 4.50 5.00

ExperimentalForce

(N)

Impact Momentum (N)


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y = 1.5584x

4.00

4.50

5.00

5.50

6.00

6.50

7.00

7.50

8.00

2.50 3.00 3.50 4.00 4.50 5.00

ExperimentalForc

e(N)

Impact Momentum (N)


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Conclusion Theoretical Values versus Experimental Values

Linear relationship that connects Experimental forceswith Impact Momentum.


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Conclusions Flat Target

Higher error percentage; mean is 12.3%

Less force required to overcome resistance of jet

Hemispherical Target

8.32% Error percentage, outlier at 0.1%

Jet creates greater forces


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Conclusions Results were acceptable

Minimum difference from jet nozzle to impact surface

Higher error percentage accredited to Timing error

Inaccuracy in observations

Meniscus of volume meter

Forces felt are directly proportional to deflection angleof fluids


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Questions?

fluids lab presentation

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