Wing Characteristics
Incompressible Flow
Team 5
King Abdulaziz University
Faculty Of Engineering
Aerospace Engineering Department
2022 - 2023
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Name | ID |
Saad Alsubie | 2035219 |
Omar Alghamdi | 2037330 |
Abdulmohsen Hakami | 1938715 |
Serag Alghamdi | 1845292 |
TABLE OF CONTENTS
Aspect Ratio
Taper Ratio
Geometrical Twist
Aerodynamic Twist
Sweep Angle
01
02
03
04
05
Saad Alsubie | 2035219
Saad Alsubie | 2035219
Serag Alghamdi | 1845292
Abdulmohsen Hakami | 1938715
Omar Alghamdi | 2037330
01. Aspect Ratio
Taper Ratio = 0.5
Twist angle = 0
NACA Airfoil = 0012
With increasing the aspect ratio, the lift coefficient will increase. The increment in the lift coefficient is reduced by increasing the aspect ratio.
4
Cl vs AoA:
Cd vs AoA:
With increasing the aspect ratio, the drag coefficient will decrease. The amount reduction in the drag coefficient is not constant with increasing the aspect ratio.
Discussion
Cl vs AoA:
Wingtip vortices work to minimize lift coefficient, as we all know. Therefore, by reducing the wingtip vortex effect, we can save more lift coefficient, which is what the aspect ratio does.
Cd vs AoA:
Drag coefficients in finite wings consist of parasitic drag (non-lift drag) and induced drag (lift-dependent drag). As we've stated previously, increasing the aspect ratio reduces the total drag by overcoming wingtip vortex, the cause of induced drag.
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The lift/drag ratio will also increase by increasing the aspect ratio. The lift/drag ratio increment is reduced by increasing the aspect ratio.
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L/D vs AoA:
BM vs AoA:
By increasing the aspect ratio, the bending moment will increase as well. The increment in the bending moment is reduced by increasing the aspect ratio.
Discussion
L/D vs AoA:
The L/D ratio is not more than the lift coefficient over drag coefficient. Thus, as we have coved for the higher aspect ratio has higher lift coefficient and lower drag coefficient and that will lead to higher L/D ratio as result.
BM vs AoA:
The bending moment is not more than the summation the vertical forces that and moment that applied of the wing. One of the major constructed force in this situation is the weight. Thus, the increasing in aspect ratio will cause more wight and that means higher bending moment.
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As the aspect ratio increase, the lift amount increase. The slope decrease after the peak point gets gentle. The increment in the lift distribution is reduced by increasing the aspect ratio. The curve of the three-aspect ratio is the closest lift distribution shape to an elliptic curve.
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The local lift distribution over the wingspan at 4°:
The lift coefficient over the wingspan at 4°:
As the aspect ratio increases, the lift coefficient increases. The increment in the lift coefficient is reduced by increasing the aspect ratio. The slope of a curve that comes after the intersection gets gentle.
Discussion
Cl vs AoA:
The curve started from zero Cl at zero angles of attack, which indent faction to tell us the airfoil is symmetric. Moreover, we can notice that the linear relationship ends at 11 angles of attack, which is the maximum Cl (1.144); after this angle is the stall regen (AoA > 11), which describes why the Cl values are dropping. However, the potential flow is studied here, so the flow will permanently be attached to the airfoil surface.
Cd vs AoA:
As we know, the drag in the infinite wing contains drag due to skin friction and drag due to pressure. This foundation will help us understand why the Cd didn’t start from zero at zero degrees, which is drag due to skin friction. This type of drag will remain constant with the changing angle of attack. The behaviour is because Reynold’s number doesn’t change in this case. From 0 degrees through 11 degrees, the increase in Cd (drag due to pressure) is tiny compared to the rise after 11 degrees, in which the flow is in the stall regen, as we have mentioned before.
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02. Taper Ratio
Aspect Ratio = 0.5
Twist angle = 0
NACA Airfoil = 0012
The amount of the lift coefficient for the different aspect ratios increases with decreasing the taper ratio. However, the taper ratio of 0.4 has the best CL performance.
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Cd vs AoA:
By increasing the taper ratio, the drag coefficient will decrease.
Cd vs AoA:
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Cd vs AoA:
By increasing the taper ratio, the bending moment will increase as well. The bending moment increase is reduced by increasing the taper ratio.
Cd vs AoA:
The lift/drag ratio for the difference taper ratios is almost identical.
The highest lift around the root is the wing with a taper ratio of 0.4, and the highest lift around the tips is the wing with a taper ratio of 1. The closest lift distribution shape to an elliptic curve is the curve of 0.4 taper ratio.
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The local lift distribution over the wingspan at 4°:
The lift coefficient over the wingspan at 4°:
The highest lift coefficient around the root is the wing with a taper ratio of 1, and the highest lift coefficient around the tips is the wing with a taper ratio of 0.1.
03. Geometrical Twist
Aspect Ratio = 6
Taper Ratio = 0.5
NACA Airfoil = 0012
The increase of angle of twist will cause the CL to decrease.
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Cl vs AoA :
CDi vs AoA :
Increasing the twisting angle will decrease Cd.
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Bending Moment vs AoA:
With the increase of the twist angle the L/D ratio decreases, also small angle of attack less than 2 have a negative L/D .
L/D vs AoA:
Bending Moment decreases as the twist angle increases.
The increase of twist angle gave us the highest lift at the tip, and then the lift will reduce when it get close to the root. also increasing the twist angle will give us a shape close to (elliptical shape).
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The local lift distribution over the wingspan at 4°:
The lift coefficient over the wingspan at 4°:
Increasing the twist angle will have a better lift distribution in the tip and the root and make the possibility of stalling at the tip lower.
Disscussion:
04. Aerodynamic Twist
Aspect Ratio = 6
Taper Ratio = 0.5
Twist angle = 0
As the zero-lift angle of attack decrease in a negative sign, we can notice the increase in lift since -4,-4 airfoil will give the best lift at the same angle of attack.
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Cl vs AoA :
CDi vs AoA :
As the zero-lift angle of attack decrease in a negative sign, we can notice an increase in drag coefficient as well.
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Bending Moment vs AoA:
Decreasing the zero-lift angle will affect the Lift/Drag ratio causing a noticeable decrease in L/D, the highest L/D ratio is at (-4,0).
L/D vs AoA:
For the bending moment, it is quite clear that the bending moment will increase on the aircraft as we decrease the zero-lift angle, thus (-4,0) is more desirable to have better controllability over the aircraft.
Here in the local lift, it is clear that the desirable airfoil is (-4,0) since it shows a closer curve to the target elliptic curve, thus high efficiency lift distribution.
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The local lift distribution over the wingspan at 4°:
The lift coefficient over the wingspan at 4°:
For the lift coefficient distribution, the more we decrease the zero-lift angle, the higher the lift coefficient near the tip, which is undesirable since it may cause tip stall. Thus, (-4,0) is better with lower lift coefficient at tip.
05. Sweep Angle
Aspect Ratio = 5
Taper Ratio = 0.7
Twist Angle = 0
NACA Airfoil = 0012
CDi vs AoA:
Similarly, increasing the sweep ingle results in decreasing which is more desirable. We can notice how 50 sweep angle will cause the smallest drag among the rest.
Cl vs AoA:
We can see that the more we increase the sweep angle, the more the lift coefficient making 50 sweep angle generating less lift compared to the other angles.
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L/D vs AoA :
Although having a higher sweep angle will lead to a lower lift coefficient, we can see through the graph that 50 sweep angle will give the best L/D ratio.
Bending Moment vs AoA:
Bending Moment decreases as the sweep angle increases. Thus, it is better to have higher sweep angle (50) since it will give more control over the aircraft.
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The local lift distribution over the wingspan at 4°:
When the sweep angle increases the chance of tips stall increase. Which means that the lower sweep angle is more desirable in this case, 10 sweep angle.
The lift coefficient over the wingspan at 4°:
Sweep 10 has the closest shape to the elliptic distribution.
The lower sweep angles are resulting higher and better local lift distribution closer to the target elliptic curve distribution.
Sweep angle
In the previous graphs of the sweep angle section, we fixed the taper ratio, aspect ratio, and the lift angle as follows respectively, 0.7,5.0, and 0, then, we got five wings with five different sweep angles from 10 to 50 with step of 10 degrees.
The drag and lift coefficients were decreasing with increasing the sweep angle, and wing with the sweep angle 50 has the minimum drag and lift coefficients.
When we divided the lift coefficient over the drag coefficient of the five sweep angles, we noticed that the sweep angle 50 has the best flight range performance because it was the highest lift-to-drag ratio.
The bending moment versus angle of attack graph shows that, when the sweep angle increases the bending moment decrease, so the highest bending moment was when the sweep angle is 10, and the lowest bending moment is when the sweep angle is 50 and from this point we can say increasing the sweep angle improves the lateral controllability of the aircraft.
The sectional lift coefficient graph shows increasing the sweep angle result in decreeing sectional lift coefficient along with span wise. Furthermore, it shows how the chance of the tips stall increases with increasing the sweep angle, so the curve of sweep 10 is the best lift coefficient distribution because it has the lowest risk chance of tip stall, unlike the curve of sweep 50 which has the highest chance of tip stall.
In the graph of local lift distribution, because increasing the sweep angle result in decreasing sectional lift coefficient, the local lift distribution decreases as well. In addition, the green curve which belong to the target curve is almost identical to the sweep 10 curve, which means that when the sweep angle is 10, the wing shape will be the closest to the elliptic distribution shape, also, because the effect of the downwash, the maximum values near to the roots are being decreased toward the wing tips.
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Thank You