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Venturi Tube Laboratory

Banscbach-Arnold-Wallace-Webster

Objective

The following laboratory procedure is carried out to provide insight in to how a Venturi tube works and

what effects it is having on pressure, velocity, and energy losses. Since Bernoulli’s equation takes in to

account pressure, velocity, and total energy, it is only logical that we will be able to assess the Venturi

tube and the flow inside using this equation along with a few others. As flow goes through the Venturi

tube, we will observe how the velocity, pressure, and energy of the fluid react as a byproduct of the

cross sectional area increasing or decreasing.

Background Information

In order to understand what is going on in this laboratory experiment and why the fluid flow properties

are acting the way they do, it is necessary to know a few things first. Little background information was

given about this lab coming in and through this experiment, we would learn more in depth knowledge of

the subject. What we knew going in was that the Bernoulli's equation neglects energy losses through the

system. We also knew that in the real world experiment that there would in fact be energy lost when

water passed through the tube. So from this disagreement, we would have a point of comparison and a

question to be answered, "What is the theoretical energy loss versus experimental energy loss?"

Another fundamental understanding was when water passes through a constricted tube, the velocity

increases and the pressure will decrease. Vice versa the velocity will decrease and pressure increase

when the tube expands. How much that pressure and velocity change once the fluid goes through this

contraction/expansion process will give us another aspect to compare to. We will need to compare and

answer, "Theoretically and experimentally how much pressure is lost and does the system regains its

initial pressure?" Since this is all we understand of this topic and how important it will be to our

calculations, we will go back and start from the beginning to help gain some knowledge.

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First we will assume that we are working with a Newtonian fluid, it is incompressible, and lastly it is in

steady state. Since this lab is dealing with water as the liquid flow, we know that these statements are

true. This means that we will have the same flow rate through the entire system, and we are not

changing anything chemically or at a molecular level. From these statements we earlier derived the

equation:

Volumetric flow rate(Q)=(Velocity point )× (Area point )

, where Q is volumetric flow rate, V is velocity of the flow, and A is the cross sectional area of the piped

flow.

Next, we have Bernoulli’s equation:

P+γZ+ ρV2

2g=Constant

, where P is Pressure, Z is elevation relative to our datum, V is velocity, γis specific weight of the fluid,

and ρ is the density of the fluid. Since we know that vertical pressure change is a correlation between

vertical displacement and the specific weight of a fluid, we can see that the second term in this

equation is going to be in units of pressure. Furthermore, V squared gives units of m2

s2 and ρ gives units

kgm3

so the third term would produce kg/m*s2 which is the unit makeup of a Pascal, a pressure once

again.

So what does this tell us? Well, if we divide everything by the specific weight, it produces an equation

where all of the units are in meters or displacement rather than in units of pressure—and still the

equation is equal to a constant. The equation becomes the following:

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Z+ Pγ+ V

2

2 g=Constant

Each of these terms has units of “head”. The first is elevation head, the second is pressure head, and

the third is velocity head. This equation is great in the fact that it gives us direct visual interpretation of

physical phenomenon—they each have visual meaning. In a Venturi tube as well as any flow, each head

coefficient can be measured; and where one is difficult or near impossible to be measured, you can use

Bernoulli’s equation to calculate it by knowing the three values at another point in the system. The

following is a diagram shows where we will be calculating elevation head, pressure head and velocity

head.

After finding these three head coefficients and numerous other factors, we will use them to compare

and answer the questions previously stated. To do this we will look at values collected from the

experiment (experimental) and what we get from solving by hand (theoretically). This will give us a very

good comparison between the two, but we wondered if there was a way to find a comparison

somewhere between the "real world" and "on paper." To answer this we decided to model and

simulate our Venturi Tube using a computer program named SolidWorks.

SolidWorks is a very powerful program used to accurately construct objects and then run simulations

on said object. We reasoned this would be satisfy the comparison between experimental and

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theoretical. We were able to find the manual online and were able to get all the dimensions and

materials needed to accurately construct this model.(see attached TecQuipment H5 Venturi Meter

Manual) We not only wanted to run this simulation to help our comparisons, but also help visualize

what was going on through this Venturi Tube.

Experimental Setup & Procedure

Materials List:

Safety Goggles

(1) TecQuipment H5 Venturi Meter with flow control

(1) Pump with variable flow control

(1) Gravimetric Hydraulic Bench or other device for finding flow rate (We used TecQuipment

Hydraulic Bench)

(1) Stopwatch

Setup & Procedure:

In order to set up the lab correctly, we had to make sure that the Venturi Meter had all of its parts. It

may seem unnecessary but considering ours had a missing pressure release valve, we will from here on

out never cross out this critical step. This issue was quickly remedied by using a value from an ideal

Venturi Meter in the closet within the lab. It was also important to make sure the tube was sitting

balanced on the table, because to neglect energy losses due to friction, the fluid could not be flowing

past the walls of the apparatus with any immeasurable angle. Once the Venturi tube was looked over

and in working condition the bench was turned on and we then went about finding volumetric flow rate.

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We know that volumetric flow rate is simply volume divided by time. Furthermore we know that

volume is equal to mass over the density of the fluid flowing. Using methods found in Lab 2 (Gravimetric

Hydraulic Bench) we can find volumetric flow rate essentially by flowing a known fluid (water) into a

suspended catch basin and countering the weight of the fluid with weights on the end. Once enough

water has gone into the basin (initially empty) that the apparatus has become horizontal, a known

amount of weights were added at the end of the moment arm and a timer was started. Once the weight

of the water in the basin has countered the weight at the end and has become horizontal again, the time

is stopped. The ratio of the moment arm of the weight at the end to the catch basin is 3:1. So 3 is

multiplied by the mass. We want the flow rate in the end to be in liters per second so we convert the

cubic meters to liters knowing the conversion between the two is 1000 liters for every cubic meter.

These calculations can be found in Equation 1 of the Equations Sheet section of this report. Once we

found the volumetric flow rate through the tube itself, we were able to proceed with the lab procedures

Follow these steps for repeatable results:

(1.) Set up a flow path that goes from the reservoir of the hydraulic bench to the pump, up through

a hose, through the Venturi Meter, and out through a hose into the top of the hydraulic bench

dispersing into the weigh tank.

(2.) Turn the pump on and proceed to adjust the pressure valve by the orface on the top of the

Venturi Meter as well as the value on the discharge end of the tube until the maximum

measurable water height is achieved.

(3.) When a steady state flow has been reached, complete the before stated steps to find the

volumetric flow rate. You will need your stopwatch for this.

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A (m) B C D E F G H J K LTest 1 0.518 0.380 0.377 0.271 0.083 0.135 0.211 0.264 0.299 0.321 0.338 0.347Test 2 0.459 0.291 0.289 0.202 0.049 0.092 0.154 0.195 0.223 0.241 0.255 0.263Test 3 0.210 0.083 0.081 0.059 0.020 0.026 0.045 0.056 0.064 0.068 0.071 0.076

Test # Q (L/s) Experimental Pressure Head at Pre-Selected Points

A (pascals) B C D E F G H J K LTest 1 0.518 3,727.8 3,698.4 2,658.5 814.2 1,324.4 2,069.9 2,589.8 2,933.2 3,149.0 3,315.8 3,404.1Test 2 0.459 2,854.7 2,835.1 1,981.6 480.7 902.5 1,510.7 1,913.0 2,187.6 2,364.2 2,501.6 2,580.0Test 3 0.210 814.2 794.6 578.8 196.2 255.1 441.5 549.4 627.8 667.1 696.5 745.6

Q (L/s) Pressures at Pre-Selected PointsTest #


Test # Q (L/s) Velocity Head at Pre-Selected Points



(4.) When flow rate has been calculated, write down the values of each of the heights of water

across the Venturi Tube pipelets. These values are the measured (or experimental) pressure

head readings. Accuracy here is important for later on.

(5.) Lastly, you will need to repeat steps 2-4 two more times EXCEPT NOW WE WILL VARY THE

HEIGHT OF THE WATER IN THE PIPELETS FOR THE LAST TWO. This way, you will be able to see

if energy loss across the pipelets is related to the flow going across the tube.

Experimental Data & Statistical Analysis of Data

Data

Through this experiment we have collected data from three different types of calculations. The first is

what we found from the lab (Experimental). Second what we calculated based from a few factors in the

lab experiment (Theoretical). Lastly from our simulation that was completed in the program SolidWorks

(SolidWorks Simulation). This data is presented in the tables and graphs below:

Experimental Data:

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Table E-1

Table E-2

Table E-3

A (m/s) B C D E F G H J K LTest 1 0.518 0.9757 1.2255 1.9555 2.5758 2.3397 1.9336 1.6228 1.3828 1.1914 1.0377 0.9770Test 2 0.459 0.8646 1.0859 1.7327 2.2824 2.0732 1.7133 1.4380 1.2253 1.0557 0.9195 0.8657Test 3 0.210 0.3956 0.4968 0.7928 1.0443 0.9485 0.7839 0.6579 0.5606 0.4830 0.4207 0.3961

Test # Q (L/s) Velocities at Pre-Selected Points


Test # Q (L/s) Experimental Total Head at Pre-Selected Points

LocationDistance from

Vertical Datum(mm)

Diameter of Pipe (mm)

A -54 26B -34 23.2C -22 18.4D -8 16E 7 16.79F 22 18.47G 37 20.16H 54 21.84J 67 23.53K 82 25.21L 102 26



Theoretical Data:

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A (pascals) B C D E F G H J K LTest 1 0.518 3,722.7 3,447.8 2,286.8 881.2 1,461.7 2,329.4 2,881.9 3,242.6 3,489.0 3,660.3 3,721.4Test 2 0.459 2,853.7 2,637.9 1,726.3 622.7 1,078.5 1,759.7 2,193.6 2,476.8 2,670.3 2,804.8 2,852.8Test 3 0.210 813.5 768.3 577.5 346.5 441.9 584.5 675.3 734.6 775.1 803.2 813.3

Theoretical Pressures at Pre-Selected PointsTest # Q (L/s)

Table T-1

Table E-4

Table E-5

Table E-6



A (m/s) B C D E F G H J K LTest 1 0.518 0.9757 1.2255 1.9555 2.5758 2.3397 1.9336 1.6228 1.3828 1.1914 1.0377 0.9770Test 2 0.459 0.8646 1.0859 1.7327 2.2824 2.0732 1.7133 1.4380 1.2253 1.0557 0.9195 0.8657Test 3 0.210 0.3956 0.4968 0.7928 1.0443 0.9485 0.7839 0.6579 0.5606 0.4830 0.4207 0.3961

Test # Q (L/s) Theoretical Velocities at Pre-Selected Points


Test # Q (L/s) Theoretical Pressures head at Pre-Selected Points


Test # Q (L/s) Theoretical Total Head at Pre-Selected Points

SolidWorks Simulation:

A B C D E F G H J K LPressures (pascals) 3,625.5 3,601.8 3,255.0 2,935.6 2,516.4 3,280.1 3,732.0 3,724.8 3,717.8 3,713.4 3,714.4Velocities (m/s) 0.9703 1.2090 1.6433 1.7493 1.8506 1.2806 0.8123 0.7550 0.7480 0.6815 0.7686Velocity Head (m) 0.048 0.074 0.136 0.154 0.173 0.083 0.033 0.029 0.028 0.023 0.030Pressure Head (m) 0.370 0.367 0.332 0.299 0.257 0.334 0.380 0.380 0.379 0.379 0.379Total Head (m) 0.417 0.441 0.468 0.454 0.429 0.417 0.414 0.408 0.407 0.402 0.408

Measurements along Pre-

Selected Points

Point Along TubeSolidWorks Simulations for Test 1 Conditions

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Table T-3

Table T-2

Table T-4

Table SS-1

A (pascals) B C D E F G H J K LTest 1 0.518 3,727.8 3,698.4 2,658.5 814.2 1,324.4 2,069.9 2,589.8 2,933.2 3,149.0 3,315.8 3,404.1Test 2 0.459 2,854.7 2,835.1 1,981.6 480.7 902.5 1,510.7 1,913.0 2,187.6 2,364.2 2,501.6 2,580.0Test 3 0.210 814.2 794.6 578.8 196.2 255.1 441.5 549.4 627.8 667.1 696.5 745.6

Q (L/s) Pressures at Pre-Selected PointsTest #

Figure SS-1



Total Head Plots:

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Figure SS-2

Figure SS-3

Figure SS-4



0 20 32 46 61 76 91 108 121 136 1560.260

0.280

0.300

0.320

0.340

0.360

0.380

0.400

Total Energy Test 2

TheoreticalExperimental

Distance (mm)

Tota

l Ene

rgy

(m)

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Figure TH-1

Figure TH-2



0 20 32 46 61 76 91 108 121 136 1560.050

0.065

0.080

0.095

0.110

0.125

Total Energy Test 3

TheoreticalExperimental

Distance (mm)

Tota

l Ene

rgy

(m)

Pressure Head Plots:

0 20 32 46 61 76 91 108 121 136 1560.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

Pressure Head Test 1

ExperimentalTheoreticalSolidWorks

Distance (mm)

Pres

sure

Hea

d (m

)

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Figure TH-3

Figure PH-1



0 20 32 46 61 76 91 108 121 136 1560.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350


ExperimentalTheoretical

Distance (mm)

Pres

sure

Hea

d (m

)

0 20 32 46 61 76 91 108 121 136 1560.000

0.014

0.027

0.041

0.054

0.068

0.081


ExperimentalTheoretical

Distance (mm)

Pres

sure

Hea

d (m

)

Statistical Analysis

The data from Table E-1 was recorded directly from the piplet readings on the Venturi Meter.

Subsequent data from Table E-2, E-3, E-4 & E-5 was calculated from initial conditions and from data in

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Figure PH-2

Figure PH-3



Table E-1. They were not directly measured from the apparatus. Data in Table E-6 shows the distance (in

mm) of each point from the vertical datum. It also gives us the diameter of the pipe at the location.

Data gathered in Table T-1, T-2, T-3 & T-4 was all calculated theoretically using equations on the

Equations Sheet. Those equations were then entered into a program called MatLab to help eliminate

human error and speed up the process of data collecting. The MatLab code can be found at the end of

this report in the Reference Section.

All of the data that is presented in Table SS-1 came from the SolidWorks Simulation that modeled the

flow through the Venturi Tube using the conditions from Test 1. We were only able to give data based

for the first test due to time constraints and wanting to focus more time on what was required of the lab

report. This test was run solely as another way to compare the effects of the properties of the fluid in a

Venturi Tube as well as to help visualize the data. In Figures SS-1, SS-2, SS-3 & SS-4 the pressure change

along the length of the pipe is very easy to see. More detail of the SolidWorks Simulation is provided in

the Results, Conclusions & Recommendations Section.

In the Figures TH-1, TH-2 & TH-3, the total head (or total energy) at each point is plotted along the

distance along the tube. Note: The horizontal axis plots the distances from 0-156mm as opposed to the

given distances in Table E-6 to better display the data clearly. The total head in all three is measured as a

unit of length as expected. Only in test 1 is the SolidWorks Simulation compared as explained before and

further later in this report. Each plot shows what was expected with a couple outliers in similar

locations.

In Figures PH-1, PH-2 & PH-3, the pressure head at each point is plotted along the distance of the tube.

Again here we are using the horizontal axis to show distances from 0-156mm as opposed to what was

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given in Table E-6. Also represented again was the comparison of the SolidWorks Simulation only in test

1. All three plots show what you would expect with only a few outliers.

Results, Conclusions & Recommendations

Looking at the data that was collected in the numerous tables and figures, many conclusions can be

drawn from them. What we are concerned with is first why the data we collected turned out the way it

day. Secondly, what could have caused any skews in data and what we can conclude from our

comparisons. Lastly what could we have done differently and what we recommend for future tests. For

all three types of comparisons being made (Theoretical vs. Experimental vs. SolidWorks Simulation) we

have what we assume to be our initial conditions. These conditions are volumetric flow rate (Q), velocity

at each point (v) and a constant (C) that was found to help find data in all three cases. Another

important topic to discuss is the elevation head term of Bernoulli’s equation. For our lab we placed our

horizontal datum through the center of the pipe. The reason for is so we could completely eliminate the

elevation head entirely as it would cancel out throughout the system. When we leveled the venture

tube initially, we essentially eliminated this term.

Even though volumetric flow rate and velocity came from our experimental data sets, they are needed

throughout the lab for other calculations and are thus assumed to be givens (or initial

conditions).Without these we would not be able to find our theoretical values and not know what to

plug into our SolidWorks Simulations. Our other initial condition is the dimensions of the Venturi Tube.

First, let's take a look at each of the results in more depth and see what they mean for the experiment

as a whole.

Results in Detail:

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What we can gather from all this data is important to us because understanding why some data is what

it is can, in itself, help us understand the process. In Table E-1 we physically measured the pressure head

at each of the manometer tubes for the three different tests. What changed in those tests were the flow

rate and subsequently the velocity at each point and the pressures. There is some human error in the

fact that each was physically read off the meter and each could be off by as much as 2-3mm. Secondly

there comes in the error that the flow rate is not as constant as we would like it to be. No one in the

group adjusted the flow rate manually, but the pump itself is not physically able to keep the flow rate

constant.

In the Tables E-2, E-3, E-4 & E-5, we had to calculate these values ourselves and were not able to

measure them. Although we were not able to measure them, does not mean they are necessarily

theoretical because they were all calculated from values in Table E-1 and our initial conditions.

Data in Tables T-1, T-2, T-3 & T-4 are all of the theoretical values to compare against our experimental

values. Each of which were found from the equations provided on the Equations Sheet. First thing that

need to be found for the theoretical calculations is the constant (C). To find the constant (C), set up the

Bernoulli’s Equations and set it equal to some constant. This constant will be used in the rest of the

theoretical calculations. Since we cannot theoretically calculate what the initially internal pressure is, we

have to use our measured pressure head at point A to find the pressure at that point. We will also use

the experimental volumetric flow rate to find the constant at point A. So basically we are assuming the

volumetric flow rate (Q) and the constant (C) would be given to us as “Initial Conditions” to solve this

theoretically. The Constant (C) can be found using Equation 2.

Table T-2, velocities at each point, can be found using Equation 4. For this equation you will have to

know the area at each point, which can be found from the diameter of the pipe given in Table E-6 Table.

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You will also need to know the volumetric flow rate for each test. Note: you will need to change the

volumetric flow rate from liters per second to cubic meters per second using the conversion given

previously. Table T-1, pressures at each point, can be found using Equation 5. For this you will have to

know the Constant for that particular test, specific weight of water and the velocity at that point which

can know be found in Table T-2. This equation comes from Equation 3 simply multiplying both sides by

the specific weight of water to get the pressure by itself.

In the data set, Table T-3, the pressure head at each point was found. To find these values, use Equation

3 from which you will need to know the velocity at each point and the constant (C) for that

corresponding test. This equation simply sets the pressure head term equal to the constant (C) term and

the Velocity Head term. Lastly in Table T-4, the total energy (or total head) is found using Equation 7.

When using this equation, the elevation head will be zero as it has for this entire experiment. The

pressure head will be used from what was found earlier in Table T-3 at each point as it involves the

constant (C) in each. The velocity head will come from what was found earlier of the velocity at each

point along the tube.

The values that are presented in Table SS-1 is the data that was spit out by the SolidWorks Simulation.

Figures SS-1, SS-2, SS-3 & SS-4 are provided to help give a better visual of the pressure changes as the

fluid moves along this pipe. After we decided to reproduce this Venturi Tube with this program and run

a flow simulation through it, we were able to decide what we wanted find. This program gave us nearly

an endless list of items that could be calculated, but we decided for the program to just find the

pressures and the velocities at each point. From this data, we could use Equation 5 & 6 to find the

pressure head and velocity head respectively. We could also then use Equation 7 to calculate the total

head or total energy for us.

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Conclusions:

After all of the data has been collected and gone over in more detail, the most important question is,

"What can be learned from all of this?" Secondly we need to ask ourselves, "Can we answer the

questions posed in the beginning of this report?" To answer the questions we need to find out what was

learned from our Venturi Meter lab experiment.

The first point of comparison is the amount of pressure that is lost through the system. From Figure PH-

1 you can clearly see that the pressure head through the contraction stage is similar for the

experimental and theoretical values. Pressure head is a unit of measuring energy through pressures and

we would expect to see non significant losses in energy. In the expansion state, it shows that the

experimental values are tracking below that of the theoretical values. What does that tell us? Well we

know that Bernoulli's equation neglect energy loss so we would expect to see no energy loss in our

experiment as well. This is present in the fact that the theoretical pressure heads are nearly identical at

point A (0.37948m) to point L (0.37935m), the only difference most likely being a rounding error.

If you were to compare the pressure heads at point A (0.380m) and point L (0.347m) for the

experimental values you would find a much more noticeable difference. Why? Simply because the

experimental value plots the energy losses through the tube as you would expect in a real life situation.

Why there exists such energy losses are mostly caused by energy lost to friction along the tube. Friction

is caused by the roughness of the inside of the tube. Also we found that there was quite a large amount

of what appeared to be calcium buildup along the inside of the Venturi Tube. All of this adds up to

explain why there is a significant loss of energy through the tube.

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Another way to "see" the energy losses goes back to initial background information, "as velocity

increases, pressure decreases and vice versa." If there are obstructions in the tube, such as calcium

buildup and roughness of the material, we expect the velocity of the fluid through that tube to slow

down. If the velocity slows down, the pressure will be higher than what was theoretically calculated.

This is shown in Figure PH-1, PH-2 & PH-3 in the contraction portion as the experimental values are

higher than theoretical values. Although in the expansion portion, the energy losses are so significant

that they overrule this reasoning and fall below the expected theoretical values.

We also plotted our results from the SolidWorks Simulation that we found to be interesting. First off

knowing the material and modeling of the Venturi Tube, this simulation represents a "brand new, never

before used," Venturi Meter like the one we tested on. The difference comes in the fact that the inside

is much smoother initially which results in fewer fluctuations in pressures and velocities. This turns out

more like a theoretical Venturi Tube as it models an "ideal" situation. Because of this the pressure head

returns almost back to normal from point A to point L. What is also interesting to note is that fact that

the pressure does not drop nearly as much as it was calculated to be. Our reasoning for this is we may

not have accurately selected the material for the tube and the roughness contributed to lower velocities

and thus higher pressures. Note: From the manual of this Venturi Meter, the material was found to be

Aluminum but which grade was not specified. (See attached TecQuipment H5 Venturi Meter Manual)

Other conclusions that can be made are the total energy losses through the Venturi Meter. From Figures

TH-1, TH-2 & TH-3, the total energy lost can clearly be identified. There are a couple different ways that

you can track the energy losses through the system. The first being the total head at each point along

the tube. The base line for comparison is actually our theoretical energy losses as Bernoulli’s equation

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neglects any losses due to energy and thus produces a horizontal line. So at each point you can judge

how much energy was lost or gained.

In the contraction portion you can see where the total energy of the points jumps above the base line.

This is because the rapid increase in velocity contributes to higher energy before the energy lost due to

friction has time (or contacted are of pipe) to make a difference in total energy. Essentially there is more

energy gained in velocity in contraction than there is energy lost due to friction. This is not true for all

cases as it would surely change in the length of the contraction stage was changed. In the expansion

stage if where you will notice more losses due to energy and less energy gained in velocity. As the tube

expands the pressure increases and the subsequently velocity decreases. The fluid is also in contact with

the pipe for a longer amount of time and thus creates more energy lost due to friction. So all in all the

overall result for the expansion stage is more energy lost due to friction than there is energy gained in

velocity. For both the contraction and expansion portion, this idea is clearly shown in Figures TH-1, TH-2

& TH-3. The SolidWorks Simulation also proves this by nearly matching the data points from our

experimental portion.

Another way to track energy loss is the total energy for the whole system. This is simply where the

difference in energy at the start of the system to the energy at the end of the system. In Figure TH-1 the

total head value at point L (0.3956m) is significantly lower than what the energy was at the start at Point

A (0.4285m) for test 1 conditions. Certainly you would expect these difference to change at the flow rate

is changed. This can be seen both in Table E-5 as well as in Figures TH-1, TH-2 & TH-3. You would expect

as the flow rate decreases (and velocity decreases) that the total energy both is individual states and

total for the system would decrease. As in our three tests, each with a more decreasing flow rate, the

total energy becomes less and less. There is less energy gained in velocity and less energy lost due to

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friction in both the contraction and expansion stages. This in turn gives us plots that are similar but with

differing magnitudes of total energy at individual points. The result in difference in test 2 in at point L

(0.03012m) to point A (0.3291m) shows less energy loss in total, but negative in value once again.

Furthermore the same can be said for test 3 point L (0.0840m) and point A (0.0910m), respectively.

Answers to Initially Stated Questions:

“What is the theoretical energy loss versus experimental energy loss?”

The results we found show that compared to the theoretical energy losses the experimental losses were

significantly higher. For example in Test 1 our total head dropped .0329m which is an energy loss in the

system. The theoretical values did not change with respect to the length of the pipe, because there

should be no losses in energy due to friction in a theoretical case (as Bernoulli’s equation suggests). The

total energy of the system is dampened by the losses in friction. The end result is a loss in total energy

due to losses contributed to friction. This is shown in Table E-5 and T-4.

“Theoretically and experimentally how much pressure is lost and does the system regain its initial

pressure?”

Theoretically the pressure loss throughout the system is insignificant, and the small difference in values

from point A on the pipe to point L is contributed to a rounding error. This shows that the theoretical

pressure does reach its initial pressure in the end, and this is because theoretically there shouldn’t be

any energy losses due to friction across the pipe. In the case of the experimental data the pressure

drop is significantly different across the pipe. The values start out close to the theoretical values, but by

the end of the pipe the pressure has dropped off a good deal. The final pressure is a lot lower than the

initial pressure. This is shown in Tables T-1 and T-2. This drop in pressure across the pipe is due to

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friction across the pipe from factors like calcium build up, roughness of the pipe, and the contraction of

the pipe.

Recommendations:

Through the end of these experiments, calculations and simulations we were able to efficiently answers

that we posed ourselves in the beginning. We were also able to come up with recommendations for

others that pursue this experiment in the future. The first and most important that we would like to get

across is to have an adequate back knowledge of the topic being covered before starting. This will help

when you collect the data in the lab experiment and will know what it means “on the spot.” Next some

items will need to be accounted for that are you are not told about. Firstly being that there is significant

calcium buildup in the tube that will add more friction onto the fluid and slow velocities. Secondly that

the pump in the hydraulic bench does not keep a perfectly constant flow rate and might vary as much as

± 0.1 liters per second which is significant when you base most calculations from this. Lastly that the top

to the gravimetric hydraulic bench is not very stable and will want to “rock” back and forth. This will

throw off the pressure head readings slightly.

The last item of recommendation is that more time be devoted to this particular lab. Our class had to

force two lab experiments into one lab time frame and felt rushed while completing this lab. Luckily for

us we did this experiment second out of the two and did not feel as rushed as other groups. This would

lead to writing down some measurements wrong and not fully understanding the information being

received.

References

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"Welcome to TecQuipment." TecQuipment Ltd, Technical Teaching Equipment for Engineering.

TecQuipment Ltd, 9 Apr. 2009. Web. 16 Oct. 2013.

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