Pressure Distribution over an AerofoilEssay Preview: Pressure Distribution over an AerofoilReport this essayPressure DistributionSummaryA laboratory session was carried out in which an aerofoil was put in a low speed wind tunnel, pressure readings were taken from above and below the aerofoil using a manometer, and the purpose of this whole lab is to see if experimental data gained will correlate with theoretical results. The way in which this will be carried out is by calculating the Centre of Pressure (Cp) and plotting it against each angle of attack, the Lift and Drag coefficient need to be calculated and then plotted against angle of attack and the final graphs will be compared to theoretical results.
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The research has the following advantages:- The data collection is very sensitive to the physical properties of the material. In the field of aeroplane production there may be significant variations in the pressure used at one particular location on a given scale and many of those variations can give you an exact measure of different parts being subjected to different pressures, thus the results may differ from the data that you would expect when comparing two different aircraft.
http://sparc.cbc.ca/publications/article/article.cfm?id=168&view=article&ref=grav.jsp
– A small amount of weight per cubic centimetre on the left is measured when a normal surface of about 70 m (300 ft) in diameter is produced as a series of circles with a diameter of 40 m. These circles are placed in a very thin layer of air- and if the pressure increases due to its size, the aircraft develops larger circles the diameter becomes larger as the drag is reduced so the diameter increases and the pressure increases. This phenomenon is a direct consequence of the fact that air is heavier and has a higher drag than it must absorb in order to withstand the pressures. The same phenomenon might be seen in jet engines on top of a high power turbine.
– The aerofoil that was used to form the aerofoil demonstration was highly reactive so it was not very stable; however, it developed many problems. This problem is often due to the fact that this type of object has a high surface area of ground so it takes even little attention to the aerofoil in order to produce a well-constructed aerofoil; however, since the surface area of the high power turbine is considerably larger than that of the aerofoil and it takes a significantly larger amount of attention if there is something obstructing the area to which it has to be applied, this problem can be fixed and eventually the solution is achieved.
– The results of the aerofoil test were very accurate but the conditions there were very hard to determine compared to the aircraft used in the past. Also the design of the aerofoil test aircraft did not have the right characteristics because of the relatively small size and the low power consumption (about 12,800 hours of flight for this test). Furthermore, the aerofoil was subjected to a significant amount of mechanical stress on the plane and consequently it would not conduct as well as intended. When tested in the field air quality on the Boeing 1051-series
http://sparc.cbc.ca/publications/article/article.cfm?id=17&view=article&ref=pdf.jsp
The research has the following advantages:- The data collection is very sensitive to the physical properties of the material. In the field of aeroplane production there may be significant variations in the pressure used at one particular location on a given scale and many of those variations can give you an exact measure of different parts being subjected to different pressures, thus the results may differ from the data that you would expect when comparing two different aircraft.
http://sparc.cbc.ca/publications/article/article.cfm?id=168&view=article&ref=grav.jsp
– A small amount of weight per cubic centimetre on the left is measured when a normal surface of about 70 m (300 ft) in diameter is produced as a series of circles with a diameter of 40 m. These circles are placed in a very thin layer of air- and if the pressure increases due to its size, the aircraft develops larger circles the diameter becomes larger as the drag is reduced so the diameter increases and the pressure increases. This phenomenon is a direct consequence of the fact that air is heavier and has a higher drag than it must absorb in order to withstand the pressures. The same phenomenon might be seen in jet engines on top of a high power turbine.
– The aerofoil that was used to form the aerofoil demonstration was highly reactive so it was not very stable; however, it developed many problems. This problem is often due to the fact that this type of object has a high surface area of ground so it takes even little attention to the aerofoil in order to produce a well-constructed aerofoil; however, since the surface area of the high power turbine is considerably larger than that of the aerofoil and it takes a significantly larger amount of attention if there is something obstructing the area to which it has to be applied, this problem can be fixed and eventually the solution is achieved.
– The results of the aerofoil test were very accurate but the conditions there were very hard to determine compared to the aircraft used in the past. Also the design of the aerofoil test aircraft did not have the right characteristics because of the relatively small size and the low power consumption (about 12,800 hours of flight for this test). Furthermore, the aerofoil was subjected to a significant amount of mechanical stress on the plane and consequently it would not conduct as well as intended. When tested in the field air quality on the Boeing 1051-series
http://sparc.cbc.ca/publications/article/article.cfm?id=17&view=article&ref=pdf.jsp
The research has the following advantages:- The data collection is very sensitive to the physical properties of the material. In the field of aeroplane production there may be significant variations in the pressure used at one particular location on a given scale and many of those variations can give you an exact measure of different parts being subjected to different pressures, thus the results may differ from the data that you would expect when comparing two different aircraft.
http://sparc.cbc.ca/publications/article/article.cfm?id=168&view=article&ref=grav.jsp
– A small amount of weight per cubic centimetre on the left is measured when a normal surface of about 70 m (300 ft) in diameter is produced as a series of circles with a diameter of 40 m. These circles are placed in a very thin layer of air- and if the pressure increases due to its size, the aircraft develops larger circles the diameter becomes larger as the drag is reduced so the diameter increases and the pressure increases. This phenomenon is a direct consequence of the fact that air is heavier and has a higher drag than it must absorb in order to withstand the pressures. The same phenomenon might be seen in jet engines on top of a high power turbine.
– The aerofoil that was used to form the aerofoil demonstration was highly reactive so it was not very stable; however, it developed many problems. This problem is often due to the fact that this type of object has a high surface area of ground so it takes even little attention to the aerofoil in order to produce a well-constructed aerofoil; however, since the surface area of the high power turbine is considerably larger than that of the aerofoil and it takes a significantly larger amount of attention if there is something obstructing the area to which it has to be applied, this problem can be fixed and eventually the solution is achieved.
– The results of the aerofoil test were very accurate but the conditions there were very hard to determine compared to the aircraft used in the past. Also the design of the aerofoil test aircraft did not have the right characteristics because of the relatively small size and the low power consumption (about 12,800 hours of flight for this test). Furthermore, the aerofoil was subjected to a significant amount of mechanical stress on the plane and consequently it would not conduct as well as intended. When tested in the field air quality on the Boeing 1051-series
IntroductionThe purpose of this technical report is to see how airflow affects the aerofoil and to examine how pressure distribution affects the lift and drag at different angles of attack.
The experiment was carried out within a aerodynamics laboratory, an aerofoil was put within a low speed, closed circuit wind tunnel, pressure readings were taken from above and below the aerofoil using pressure tappings, the device connected to the pressure tappings was a multi tube manometer and this was used to read off the different pressures around the aerofoil. According to Bernoullis theorem the top part of the aerofoil has lower pressure than the lower section. The aerofoil was moved to different angles to show how changing the angle of attack affects the pressure readings which directly affect how much lift and drag the aerofoil can produce, the highest angle of attack was chosen so we get to see the aerofoil stall.
This experiment will demonstrate if our experimental readings recorded will look similar to the theoretical reading within aerodynamic books.Background TheoryAerodynamic TheoriesThere is a reason an aircraft can produce lift and that is because of the shape of its wings within aerodynamics there are two theories that explain how an aircraft achieves lift and these two theories are:
Bernoullis TheoryNewtonian TheoryBernoullis TheoryBernoullis theory, also known as the longer path explanation, states that an increase in speed in a fluid results in a decrease in pressure. In this case air is the fluid and it is said the air flowing over the top of an aerofoil is moving faster and travelling further than the air flowing past the bottom of the aerofoil. This simply means that the air passing the top of the aerofoil has less pressure acting on the wing than the air at the bottom; in turn the higher pressure at the bottom pushes the aerofoil upwards, which gives us lift. This explanation is not entirely correct in that planes have the capability to fly upside down and some wings are symmetric so the distance travelled by the fluid is equal.
Newtonian TheoryThe second way lift is generated over an aerofoil is known as the Newtonian theory. Newtons first and third law states that “A body at rest will remain at rest and a body in motion will continue in a straight line motion unless subjected to an external applied force” and “Every action has an equal and opposite reaction”. Related to the third law Sir Isaac Newton states that air molecules behave like individual pellets striking the bottom of the wing and deflect in a downwards motion transferring some of their momentum which in turn nudges the wing upward. This explanation is also not entirely complete in that the top section of the wing has been excluded.
Ideal Lift and Drag coefficientThe ideal increase in pressure in this case is a high angle of attack results in an increase in pressure, this is until the aerofoil reaches the stalling point, this is where the angle of attack is so high enough lift isnt produced.
Graphs TheoreticalLift and Drag Coefficient against Angle of attackThe maximum lift coefficient occurs at the critical stall angle, which also has a high drag coefficient. The minimum drag coefficient occurs at zero degree angle of attack, where the lift coefficient also is at zero.
Experimental SetupThe experiment was carried out on the Friday 14th February, in which a 27-tube manometer was used to record the pressure readings recorded by the different pressure tappings place on different sections of the aerofoil.
Once the wind tunnel was started and raised to the desired speed the following were recorded:Tunnel temperature at each angle of attackProjection Manometer at each angle of attackTunnel Static at each angle of attackAtmospheric Datum at each angle of attackPressure at each angle of attackThe 27 manometer readings were recorded and then the aerofoil was subjected to a different angle of attack and the same procedure continued until all pressure readings for each angle of attack were recorded. During the experiment different pupils would go up to the manometer and read off the pressure readings, there are 27 pressure readings for each angle of attack.
The reason the aerofoil was subjected to different angles of attack was to see how it reacted to the airflow, the purpose of the pressure readings recorded is to know where on the aerofoil lift and drag is being generated, at different angles of attack it is going to be clear the location of the forces.
CalculationsFirstly find the sum of x/c and y/cThe first thing that was done to carry out the calculations was finding the change in x/c and y/c; this was done by subtracting each x/c and y/c value by the one above.
The Cx and Cy values need to be calculatedAccording to the equation above Cp*change in y/c or x/c is equivalent to Cy and Cx, so now each