Results and Analysis
Speed 20 m/sec
Speed 12 m/sec
Calculations and formula used
Chord length = 0.22m, Wing length = 0.04m, ρ = 1.2kg/m3
A = Chord length x Wing length
= 0.22m x 0.04m
= 0.0088m2
Cd = Drag/AρU2
CL = Lift/AρU2
For example, speed 12 m/sec (RUN 2)
Cd = Drag/AρU2
= 0.250/ [0.0088x1.2x (0.8)2]
= 36.99
CL = Lift/AρU2
= 0.668/ [0.0088x1.2x (0.8)2]
= 98.84
Graph:
Speed 20 m/sec
Angle of attack, vs. CD
Angle of attack, vs. CL
Speed 12 m/sec
Angle of attack, vs. CD
Angle of attack, vs. CL
Discussion and Conclusion
We can clearly see the relationship between the angle of attack ∞, Cd and CL. Both Cd and CL are direct proportional to angle of attack ∞. Whenever the angle of attack ∞ increase, Cd and CL will increase too. Unfortunately, there are some human errors at the second part of the experiment which causes the inconsistent reading of result. Besides that, there are also Airfail errors which the angle of attack is hard to set at an accurate position, so that the measurements we get are not accurate as well. Furthermore, suppose that there will have the smoke to show us the flows of the air when the blower is on, but because of some safety factor in the lab so that the part of smoke was cancel.
Experiment 3
pipe surge and water hammer apparatus
Objectives
Pipe surge and water hammer apparatus
To perform investigation of water hammer and pressure waves in pipes
Theory
Pipe surge and water hammer are two related but independent phenomena which arise when fluid flowing in a pipe is accelerated or decelerated. The associated pressure transients can be damaging to pipe work or components and systems must be designed to avoid or withstand them.
Surge is the oscillation of flow in pipeline due to increase/decrease of flow rate by mean of flow control valve. Water hammer is sudden deceleration of flow due to rapid closure of the flow passage. Relationship of pressure and time during surge and water hammer action are shown in below:
Procedure
- Provides the water supply to the head tank and also incorporates a volumetric tank for flow rate measurement.
- Water enters the two test pipes via the constant head tank and discharges into the volumetric tank.
- Flow rate have to adjust so that overflow at the head tank is smooth as much as possible.
- Open ball valve at surge fully, observe pressure at manometer leg, adjust overflow if necessary.
- Record the head of water while the overflow at steady flow.
- Plot graph of head versus time
Results and Analysis
The graph of pipe surge test pressure versus time
Pipe surge resulting from a gradual change in fluid velocity is clearly seen as fluctuating changes in head in a surge shaft.
The water hammer test pressure versus time
Water hammer resulting from a rapid change in fluid velocity is clearly seen as large changes in pressure monitored using a pair of transducers and indicated using an oscilloscope.
From the graph, the maximum pressure during the water hammer phenomena is
Pmax = 0.6bar
= 6kPa
Discussion and Conclusion
As we know, surge happened when there is an increase/decrease of flow rate. We had tried 2 ways to result the oscillation in this experiment.
In the first part, we close the valve as the valve to decrease the flow rate. We can see clearly from the graph that there is an apparent wave at the beginning and after that the wave is continued slowly.
In the 2nd part, we used the water hammer to produce a sudden deceleration. As a result, it produces a huge wave at the beginning.
Experiment 4
series and parallel pump
Objectives
Series and Parallel Pump
To assess the performance characteristics of a single centrifugal pump and of two similar pumps operating in series and in parallel.
Theory
Pump is used to transfer fluid in system, either at the same level or to a new height. The flow rate depends on the height to which the fluid is pumped, and the relationship between ‘head’ and flow rate is called the pump characteristic. One common misconception about pumps is the thought that they create pressure. A single pump do not create pressure to deliver the flow rate and like this they only displace fluid, so its needs two or more pumps to create the pressure. It can be combined in series to increase the height to which the fluid can be pumped, or it combined in parallel to increase the flow rate. Therefore, in this experiment the TecQuipment H32 demonstrates how the combined pump characteristic compares with that of the single pump, and tests the characteristic of series and parallel pump as well.
Procedure
There have some part on this experiment which may be performed using the TecQuipment H32 Series and Parallel Pump Test Set:
- Performance of Pump 1 at fixed speed.
- Performance of Pump 2 at the same fixed speed.
- Performance of a single pump, range of 3 speeds.
- Performance of two pumps in series at fixed speed.
- Performance of two pumps in series at different speeds.
- Performance of two pumps in parallel at fixed speed.
- Performance of two pumps in parallel at different speeds.
- The valve for a particular pump test that will be doing is set.
- From the lab manual, we knew that the required pump speed 1, 2, and 3 is set as 750, 1150, 1800 revs/min respectively.
- The power supply is switched on when we are ready to start.
- By the adjustment of the gate valve on the outlet side of the pumps, we can set up the delivery flow rate that we want.
- The delivery pressure of each pump is read by switching to either p1 or p2. After each measurement, the valve must be switched off.
All the results are recorded
Results and Analysis
Speed 1 = 750 revs/min, Speed 2 = 1150 revs/min, Speed 3 = 1800 revs/min
Single Pump
i) Pump 1
Volume = 5 L
ii) Pump 2
Volume = 5 L
Two pump in series
(Fixed Speed), volume = 5L
(Difference Speed), volume = 5L
Two pump in parallel
(Fixed Speed), volume = 5L
(Different Speed), volume = 5L
Calculations and formula used:
Example: Speed 1 in single pump 1
Q = 5L/43.25sec
= 0.1156 L/sec
Graph:
Pressure Rise against (Flow Rate)2
Discussion and Conclusion
From the pressure rise vs flow rate2 graph it’s learnt that a very small change in pressure as flow rate increases. Pressure rises as flow rate increases.
From the flow rate vs efficiency graph, we can observe that efficiency drops as flow rate decreases. But the points obtained from experiment plotted on graph, is not accurate and precise. This could be due to some errors occurred during the experiment.
Besides that, the valve gate must be closed properly on every performance of the pumps test. For example the series and parallel pump test, if the valve gate didn’t closed it may cause the water flow to other pump way and it may make wrong result in the test. Furthermore, to get an accurate result we have to release the water tank every measurement. This is because in a stable or steady situation, the measurement result will be more accurately.
Experiment 5
Axial Flow Fan
Objectives
Axial Flow Fan
To investigate the main performance characteristics of an axial flow pump.
Theory
A Fan is simply a machine for moving air and other gases by means of a rotating impeller using propeller action or both. There are four main types of fan used for general ventilation which are centrifugal, propeller, mixed flow and axial flow. An axial flow fan is a development of propeller fan, but is more efficient mainly due to aerofoil section blades and finer clearances between the impeller blade tips and the cylindrical fan casing. It has non-overloading power characteristics which enables the correct motor horsepower to be used for any particular fan or application without causing a burn-out due to overload. To increase its performance against higher resistance, two or more impellers can be used, forming a multi-stage fan, usually with guide-vanes or contra-rotating impellers so that the air leaves the last impeller in the axial direction, without helical twist, thereby increasing considerably the maximum possible pressure available.
Procedure
- Set up the manometer for measurement of discharge side FP
- Set low manometer for measurement of suction side FP
- Adjust the inlet air damper in a certain position.
- Connect to the power line.
- Adjust the fan speed to 200rpm and 400rpm while turn on the power
- Repeat the experiment increase fan sped to 600-1200rpm
- Set upper manometer for measurement of VP at discharge side.
- Adjust fan speed to 200rpm record Vp value
- Repeat the step 8 and increase fan speed to 600-1600rpm.
Results and Analysis
Pitch angle : 60 degree
Manometer slope 1:2 (sin 25.56˚)
Manometer slope 1:2 (sin 25.56˚)
Average air flow rate, Q vs fan speed, rpm
Scale 1 : 2 (sin 25.56˚)
Note:
V = 4.043Vp
Qmean = [
Graphs :
Discussion and Conclusion
Discussion and Conclusion
From the graph, we can conclude that most of scaled experiment, the air flow rate is directly proportional to the fan speed. As the fan speed increases, the air flow rate will decrease.
Meanwhile, this experiment is a very sensitive instrument, the manometer reading always change while it’s just a slightly moving . Therefore, error is occurred easily during the experiment. We had to repeat doing the experiment due to the careless and ‘impolite’ to the gauge.
Experiment 6
Single stage compressor
Objectives
Single stage compressor
To investigate and analysis the performance of the single stage air compressor at different pressure ratio and compressor speeds
Theory
The compressor is part of a system for generation of compressed air. Such systems are used where compresses air is needed as energy source. This is particularly the case at worksites where inflammable gases from a potential explosion danger, and also where the compressed air is utilized to substitute electric power.
- Mining : Driving the machines
- Chemical industry : process control engineering
- Workshops, Petrol station : tools, paint spray gun ,tyre inflators.
- Assembly shops: automatic, pneumatic control.
Procedure
Based on the guidance of lab assistant, for constant speed experiment, the speed in motor was set up to a persistent speed since it was hard to get into constant speed as the pressure of compressor always change. The readings for the temperature and flow rates are taken once the speed is adjust to constant for each reading. There were a total of six readings were taken for this experiment. Same procedure applied to the constant pressure experiment while the pressure was set to constant to 0.9bar(a.b.s). The reading of the speed of the motor is taken.
Results and Analysis
Experiment at Constants speed
Experiment for constant pressure
Discussion and Conclusion
It is learned that the flow rate in compressor always changes. So, it the most accurate and persistent reading is advised to be taken. To obtain the constant pressure, gas in the cylinder needed to be released and adjust carefully. This is because, when the gas filled to the cylinder, the pressure fill start to increase. Since the constant reading is hard to obtain repeatedly, an accurate reading is taken. When analyzing the results for constant speed, it was found that the temperature of the compressor and motor is always varied. So, here the most persistent readings is also taken. This was the main reason that disabled from obtaining accurate reading
Experiment 7
compact Francis turbine
Objectives
Compact Francis Turbine
To study performance on Francis turbine using a small scale model.
Theory
The Francis turbine is a reaction turbine, which means that the working fluid changes pressure as it moves through the turbine, giving up its energy. A casement is needed to contain the water flow. The turbine is located between the high pressure water source and the low pressure water exit, usually at the base of a dam.
The inlet is spiral shaped. Guide vanes direct the water tangentially to the runner. This radial flow acts on the runner vanes, causing the runner to spin. The guide vanes (or wicket gate) may be adjustable to allow efficient turbine operation for a range of water flow conditions.
As the water moves through the runner its spinning radius decreases, further acting on the runner. Imagine swinging a ball on a string around in a circle. If the string is pulled short, the ball spins faster. This property, in addition to the water's pressure, helps inward flow turbines harness water energy.
Procedure
- Firstly, the water storage tank must be filled up to about ½ capacity with clean water, and the end of draft tube should be 5-6cm below the water surface.
- The power system is switched on, and then the pump will be run.
- The wicket gated of turbine is adjusted to obtain maximum turbine speed, rpm.
- By using the spring balance, the torque and the turbine speed at a certain value of torque can be measured correctly. All the measurement result are read and recorded.
- Total dynamic head, TDH, at pressure gauge, bar gauge or m is read and recorded as well.
- Torque is increased gradually by adjust the spring turbine, until the load of turbine is go to 100% which is mean the runner will be stop=0rpm. Every measure data is read and recorded. After that, the load on spring balance is released and the runner will be moved again.
- There is a small free vortex at turbine exit and it is observed and the result is recorded as well.
- The power supply will be switched ‘OFF’ when the experiment if end.
Results and Analysis
Calculation:
Torque = F x r
η = (Pout/Pin) x 100%
where
Pout = ρgQH,(ρ= 1000),
Pin = 2πNT
Discussion and Conclusion
We can clearly see the relationship between torque and rotational of the wheel. The relationship is direct proportional to each other. The wheel generates higher torque at its higher rotational state. From the result table, we can see that when the torque increasing, the speed will be getting decreasing.
Besides that, in this experiment we have met some error on the measure result. This is because the turbine machine is old and it was less maintenance, for example, the spring balance is already loose and we can’t adjust the force start at the 0 kg. So we can’t get an accurate result by use this turbine machine. Furthermore, the turbine cannot be run continuously more than 25 min. This is because to avoid an extreme heat amassing in the water storage tank. Another that, the actual flow rate that we get on the turbine machine is less than the flow rate which given at the lab manual. This is because the flow rate given at lab manual is too big for us to use.
Overall Conclusion
The overall conclusion written by us based on the experience and understanding on the each experiment done by us. Let us briefly conclude the outcome we get from all the experiment given. Most of the experiment that we’ve done in laboratory is relevant to the syllabus provided. It enables us to understand the subject better and apply it easily while experimenting. Experiment such as water hammer and forced vortex are clear examples for it. Apart from that, these lab experiments provided allow us to view the inner view of certain instruments that we’re unable to view in daily life. Sheer examples of it are, single stage compressor, compact franc is turbine and series and parallel pump. It also encourages us to understand the instruments even better.
As far as we concerned, we also had some difficult times while conducting the experiments. These are due to certain factors. First of all, the procedures provided in lab reports are slightly varied from the instruction given by our lab assistant. As we’re advised to read the lab manual and procedure before start our experiment, doing the experiment as instructed by lab assistant rather than following the procedure in lab manual creates confusion around us. We’re also had difficulties in understand function of the experiment instruments due to the specific reason.
Lastly, we also found out that there were few disjunctions in some instrument which disabled us from obtaining the accurate readings which ended up in errors. Apart from that, we’re satisfied with the lab facilities provided in laboratory.
