Morbidity and mortality are not equally distributed within a population. Explain some of the differences and the inequalities that exist in health?
The H19 Pelton Turbine Apparatus
UTD Mechanical Engineering
Fluids Lab (MECH 3115)
Dr. Hui Ouyang
Final Project for the Fluids lab
It is a group project.
You need to submit a written proposal (report) in the end. Your proposed ideas are critical. The experiment you design is a preliminary experiment to convince the reviewers that there are grounds to what you proposed and you are capable to perform the work, eventually convince the reviewers to fund your project.
The format of this proposal is based on research proposals with simplifications. National Science Foundation, when they collect proposals from research groups, ask the proposer to explain why his/her proposed research deserves tax money. Companies are similar, except that they put much more emphasis on short-term applications than on long-term intellectual merit.
In proposals, we often put equal weight on “intellectual merit” and “broader impact”. Here we focus on the broader impact so you need to explain why your project is meaningful.
• If your project does not satisfy “intellectual merit” (e.g., a minor modification of pre-existing project), your project will be meaningful if the outcome from your project is potentially useful for some practical purpose. NSF call this criterion “Broader Impact”
In your final proposal, please include the following sections:
A. Project description.
C. Broader impact (practical purpose).
D. Preliminary experiment design.
In the project description, give the reviewer a general idea about what you plan to do, how and why. In the introduction, give the background information about what has been done, what exactly you are proposing, and a plan to complete the project. In the broader impact, emphasize the practical advantages this project will bring.
A proposed preliminary experiment is the only experiment you will design for this proposal. It could be simple as long as it fits in the story of proposed work. For example, you are proposing an innovated procedure to design effective pipe systems for new buildings particularly for a mixed use of office and lab spaces. With the new design procedure, it is faster to create an effective energy-saving pipe system for different buildings. To create such a design procedure, you need funding to complete these tasks: survey the specific requirements, design the procedure (simulation and experiments), testing, and deploy the new procedure. Now you need to write a proposal about this and asking for funding to support your work. To secure the funding with a better chance, you need to design/perform a preliminary experiment. You choose to use the friction experimental
apparatus and design a friction experiment to demonstrate how pipe configuration could affect the energy consumption which can help design an energy-saving pipe system.
In the section of preliminary experiment design, please include:
(i) Description of Experimental design
(ii) Proposed experiment procedure
(iii) Predicted experimental results
(iv) Perform analysis based on predicted experimental results
No need for error analysis.
It is your responsibility to fit the experimental design into the proposal.
After you read this document, you need to do the followings:
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TecQuipment has taken care to make the contents of this
manual accurate and up to date. However, if you find any errors,
please let us know so we can rectify the problem.
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equipment. Carefully check the contents of the package(s)
against the list. If any items are missing or damaged, contact
TecQuipment or the local agent.
5 Technical Details
Spear Valve Positions ‘ ‘
To Assemble and Fit the Pelton Turbine
low.. . 9
Useful Equations 10
Turbine Power 10 ***’ ”” *** ** .. . ..
Torque (T). 10
The Pelton Wheel. 11
Torque Exerted on the Wheel 13
Power and Efficiency 14
Experiments * * ** ‘* ** * * * *** ** ** …. 17
Useful Notes 17
‘ ”’ ‘* * … . . . ..
‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ .. 17
Running in’ the Turbine..
.. ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ 17
‘ *” ‘ . . . .
Procedure. 19 .
Results Analysis… 20
Typical Results 21
Typical Calculation. 21
Conclusions 24 .
Maintenance, Spare Parts and Customer Care 25
Spare Parts 25
Customer Care. 25
Figure 1 The Pelton Turbine (H19)
The Pelton Turbine is a hydraulic ‘impulse” turbine, in which one or more water jets hit wheel. The force produced by the ‘buckets’ on a jet impact at right angles to the buckets creates a torque. This torque causes the wheel to rotate, producing power. The name “Pelton’ comes from L.A. Pelton, an American engineer who researched the best shape of the buckets needed for the turbine.
Although the concept is very simple, some very large machines of high efficiency have been developed, with power outputs of more than 100 MW and efficiencies of around 95%. On a small laboratory model, however, the output may be only a few Watts. The efficiency will then be much smaller, because losses in bearings and by air friction are proportionally higher than in a large, powerful turbine.
TecQuipment’s Pelton Turbine (H19) is a laboratory scale, vertically-mounted turbine with a band-brake dynamometer that measures torque. It allows students to do tests of performance so they can
understand how a Pelton turbine works. It works with TecQuipment’s Digital Hydraulic Bench (H1F) and existing Volumetric Hydraulic (H1D) benches. The benches provide a flow measurement and a recirculating water supply. Refer to the User Guide of the Hydraulic Bench for more details.
H19 Pelton Turbine
Jet diameter d
Mass flow rate m
Figure 7 Pelton Wheel layout
The Pelton Wheel needs a source of water in order to run. If the head of water is known, along with the
flow rate, then it is possible to find the best size of wheel to use, how fast it should rotate to obtain the
maximum efficiency, and what power it is likely to develop.
The velocity in the jet can be estimated by using the known fixed head. The diameter of the jet can then
be found from the krnown flow rate. A suitable wheel diameter can be chosen in relation to the jet size;
typically the wheel would have a diameter of 10 times that of the jet. The best speed of rotation may
then be selected, such that the speed of the buckets is approximately half that of the jet speed.
The power delivered in the jet can be calculated from the speed and cross-sectional area of the jet. The
power developed by the Pelton wheel will be less than this, in the ratio of the wheel’s efficiency, which
may be estimated by reference to the known pertormance of existing machines of comparable size and
Depending on the head and flow rate available, the size and speed of the Pelton wheel obtained in this
way may prove to be impracticable or uneconomic. Fortunately, other types of water turbine are
available to suit a wide variety of circumstances.
The Pelton wheel is usually chosen when the available head is high, but the flow rate is comparatively
Force Exerted by a Jet
Fiqure 8a shows a water jet emerging at speed v Irom à nozzle, and striking one of the buckets of the
wheel, which itself is moving at speed u. The mass tlow rate is m and it is assumed that all of the water
emerging from the nozzle strikes one or other of the set of buckets arranged around the periphery of
the wheel, although, for simplicity, just one bucket is shown in the diagram.
H19 Pelton Turbine
Relative velocity k(v u
(a) Force exerted by a jet (b) Momentum change diagram
Figure 8 VWater Jet Striking Bucket
The relative velocity at which the jet impacts on the bucket is k(v- u). The flow over the bucket is
decelerated slightly by frictional resistance at the surface. Suppose that the relative velocity, as the water
leaves the bucket, is k(v-u), where kis a velocity reduction factor with a value somewhat less than unity.
The relative velocity is incdlined at the bucket exit angle Bto the jet’s direction. The absolute velocity of
the water at exit is the vector sum of the relative velocity and the bucket velocity , as shown.
The force Fu generated on the bucket may be found by considering the momentum change, as shown
in Fiqure 8b. The incoming rate of momentum tlow in the direction of motion of the bucket is mv, and
the outgoing rate is:
m[u + k(v- u)cosß]
Note the positive sign before the relative velocity at exit, indicating addition of the relative and bucket
velocities. Note also that B is greater than 90°, therefore cosß will be neqative.
H19 Pelton Turbine
Torque Exerted on the Wheel
max mR,v (1 k cos/)
Figure 9 Vanation of torque T with speed ratio a
The force Fy produced on the bucket by the difference between these rates of momentum flows is:
F mv- m[u + k(v- u)cosß]
F m(v- u)(1 -kcosß)
It is helpful to express the ratio of bucket speed u to jet speed vas :
F mv(1-A)(1 -kcosß)
The torque T exerted on the wheel is therefore:
T = mR,v(1 -A)(1- kcosß)
We see that for a particular wheel, supplied with water at some fixed flow rate (so that both m and vare
also fixed), torque 7 varies as (1 -2). The torque therefore falls linearly from a maximum when A = 0
(i.e. when the wheel is stationary) to zero when A =I (1.e. when the bucket moves at the same speed as
the jet). This is referred to as the runaway condition.
H19 Pelton Turbine
Power and Efficiency
The power output P developed at the wheel is given by:
and noting that:
The power output may be written as:
P.mv à(1 -A)(1-kcosß)
This varies as (1 – A), so P is zero when a = 0, or when A = 1, i.e. when the wheel is either stationary
or when turning at runaway speed. Between these extremes, the power varies parabolically, with a
maximum when a = 2. The maximum value of A(1-2) is , so the maximum power output is:
P = Vamv(1 – kcosß) 1Wmax
The power input Pin in the form of kinetic energy in the jet, is:
However, the velocity calculation needs an accurate jet area, which is difficult to measure. You can
predict the area at the exit to the spear, but the jet narrows slightly downstream from the spear to a
vena contracta’, of an unknown diameter. For further proof of this, TecQuipment manufacture
equipment that allows you to measure the diameter of water jets emitting from nozzles and orifices.
Without an accurate figure for the jet diameter, the inlet pressure (shown on a small gauge) and water
flow (measured by the hydraulic bench) give a good approximation of the inlet power from:
Where O, is in m’.s and the pressure is in Pascals.
The hydraulic efficiency nh defined as the ratio of output power to input power is:
n Pin 2(1 -A)(1 -kcosß)
with a maximum value:
In terms of percentage:
n x 100
H19 Pelton Turbine
e ddsence of friction, the relative speed is not reduced by passage over the bucket surtace, 5o
vaiue or k would then be unity. Moreover, the lowest conceivable value of cosß is -1, correspond
=180°. So the factor (1 kcosß) could ideally just reach the value 2. The maximum ideal efticiency max WOuld then just reach 100%, all the kinetic energy in the jet being transformed into userui po
ut, with the water faling from the buckets with zero absolute velocity. In practice, however, surface
ricton over the bucket is always present, and B cannot reasonably exceed a value of about 165°, so you
can never reach 100% efficiency.
t must be emphasised that the hydraulic efficiency used here gives the ratio of hydraulic power
generated by the wheel to the power in the jet. The overall efficiency of the turbine will fall short of this
hydraulic efficiency due to some loss of head in the nozzle, air resistance to the rotating turbine, and
losses at the bearings.
As shown in Figure 10, you can reasonably expect a maximum efficiency of around 60% for this small
turbine. Your results should show that the turbine may not be most efficient at its maximum power
position and that the spear valve position affects maximum speed, torque, power and efficiency.
ldeal case, with k 1
and ß 180°
a (or speed)
Figure 10 Theoretical Variation of Efficiency with Speed
H19 Pelton Turbinee
To change the load, you may adjust just one load adjustment screw, but you may find better load control
if you adjust both load adjustment screws at the same time.
During these experiments, you must record lots of readings. This is much easier if you have an assistant
or if you work in small groups.
Running in’ the Turbine
The turbine uses seals to prevent water entering its bearings. When the seals are new or the turbine has
not been used for some time, the friction caused by the seals can be higher than normal. Therefore, you
must run the turbine for a few minutes before you do any tests. This is important because the turbine is
small, so friction has a large effect on its performance.
You must have the correct water level in your hydraulic bench, if it is too low, your results will be low.
Occasionally a small amount of water may pass through the turbine seals and enter the bearings towards
the brake drum. A small drain hole under the brake drum allows this water to drain away. Normally this
will be just a few drops of water. If it becomes a constant stream of water, contact TecQuipment.
H19 Pelton Turbine
To test the Pelton Turbine at different loads and spear valve settings and produce curves that show the
turbine performance and the efect of different spear valve settings.
College of Administrative and Financial Sciences
Deadline: (End of Week 12) 21 /11/ 2020 @ 23:59
|Course Name: Accounting Information System||Student’s Name:|
|Course Code: ACCT 402||Student’s ID Number:|
|Academic Year: 1441/1442 H|
For Instructor’s Use only
|Students’ Grade: …… /5||Level of Marks: High/Middle/Low|
Instructions – PLEASE READ THEM CAREFULLY
1. Under the expenditure cycle ordering materials, supplies and services are the first activity. Explain the following ordering threats with suitable example with each of these. (1.5 Marks)
a) Purchasing at inflated prices
In the period of the Coronavirus pandemic, the government imposed wearing masks, which led to an increase in demand for masks and forced consumers to buy the masks at higher prices than before.
b) Unreliable Suppliers
2. There may be several production operations threats. State any three production operations threats and also suggest some measures to control these threats. (1.5 Marks)
1- Theft of inventory
Theft makes inventory records inaccurate, which can lead to problems in filling customer orders. there are several control procedures that can reduce the risk of inventory theft. First, inventory should be kept in a secure location to which physical access is restricted
Second, all inventory transfers within the company should be documented. Inventory should be released to shipping employees based only on approved sales orders Both warehouse and shipping employees should sign the document accompany- ing the goods (or make the appropriate acknowledgment of the transfer online) at the time the goods are transferred from inventory to shipping. This procedure facilitates tracking the cause of any inventory shortages, and the accountability provided encourages employees to prepare and maintain accurate records. The use of wireless communications technologies and RFID tags can provide real-time tracking of inventory in transit, which may help reduce theft. Finally, recorded amounts of inventory should be periodically reconciled with physical counts of inventory on hand, and the employees responsible for inventory custody should be held accountable for any shortages.
2- Poor performance
Poor performance is another threat to production operations. Training is one way to mitigate this threat. Indeed, surveys of manufacturing companies report a direct relationship between time spent on training and overall productivity. It is also important to regularly prepare and review reports on performance in order to identify when additional training is needed.
3- Another threat is that both inventories and fixed assets are subject to lose due to fire or other disasters. Physical safeguards, such as fire suppression systems, are designed to prevent such disasters. However, because preventive controls are never 100% effective, organizations also need to purchase adequate insurance to cover such losses and provide for the replacement of those assets.
3. Under the payroll system of an organization we find several components such as HRM Department, Employees, Bank, Government Agencies, Insurance and other companies and various other departments. Take an example of an organization and explain the relationship of these components with reference to Payroll System of that organization. (2 Marks)
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