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International Journal of Engineering & Technology, 7 (2) (2018) 433-436
International Journal of Engineering & Technology
Website: www.sciencepubco.com/index.php/IJET
doi: 10.14419/ijet.v7i2.9196
Research paper
Feasibility study of power generation using a turbine
mounted in aircraft wing
K. Sri Vamsi Krishna 1, Shiva Prasad U 1 *, R. Sabari Vihar 2, K. Babitha 2, K Veeranjaneyulu 3, Govardhan D. 4
1,2,4 Institute of Aeronautical Engineering, Hyderabad, INDIA 500043
3 MLR Institute of Technology, Hyderabad, INDIA
*Corresponding author E-mail: shivaprasad047@gmail.com
Abstract
The main objective of this study is to increase the aerodynamic efficiency of turbine mounted novel wing. The main motive behind this
work is to reduce the drag by attaining the positive velocity gradient and generate power by converting the stagnation pressure which also
acts as emergency power source. By using the energy source of free stream air, Mechanical energy is converted into electrical energy. The
obtained power is presented in terms of voltage generated at various angles of attack with different Reynolds number. Experimental analysis
is carried out for NACA4415 airfoil at various angles with respect to free stream ranging from 0deg to 30deg from laminar to turbulent
Reynolds number. The results were obtained using the research tunnel at IARE aerodynamic facility center. The aerodynamic advantage
of this design in terms of voltage is 9.5 V at 35m/s which can be utilized for the aircraft on board power systems.
Keywords: Aircraft; Angle of Attack; Flow Visualization; Feasibility; Power; Turbine; Wing.
1. Introduction
The advancements in aeronautical field brought a tremendous
changes in the aerospace engineering by considering the major in-
novations in the technology. Although there is a remarkable in-
crease in numerical simulation analysis [17], at a greatly reduced
cost, changing the function of wind tunnels from a scaled predictor
to a data source for calibration and validation of computational
codes, but the experimental data is not harmonized in many cases
which clearly states the necessity of experimental research promi-
nence [10]. The present work is based on the experimental analysis
of novel wing model, a model with turbine mounted at the of the
leading edge section of the wing. The concept behind this design is
to reduce the load from engines and to increase the aerodynamic
efficiency, lesser fuel consumption, and the voltage power during
its overall flight period.
2. Turbine design
The design of the blade is modelled according to the leading edge
radius of the airfoil. The blade is mounted at the sectional portion
of the leading edge of the wing with rotary blades in the forward
curved motion. The rotor usually induced with eight curved blades
with chord of blade matching with the wing chord. A systematic
experimental test has been carried out to understand the influence
of velocity flow at different angles of attack over the novel wing [5]
[20]. Hence obtaining the results of power generation, aerodynamic
efficiency, fuel efficiency leads to further investigation [4]. The
study from various researchers states that there is a reduction in the
boundary layer interaction because of the flow separations over the
novel wing where the rotation of the blade takes place in the anti-
clockwise direction hence increase in the velocity at the upper sur-
face of the wing[4] [5] [14]. The variation of the velocities for the
different angle of attack over the slotted rotor wing are detailed in
this work. In the flow visualizations techniques, the streamlines on
the upper surface are comparatively more than the lower surface of
the wing. Hence there is an increase in the velocity gradient on the
surface of the airfoil. The design of the rotor blades and its scaled
dimensions play a significant role especially in the intensification
of the performance of the cross-flow rotor turbine [5] [3] [11].
The high efficiency variable speed motor and its performance, us-
ing the computational tools are detailed in [19] for analysing and
validating the performance of the model. The coefficient of lift,
drag and pressure forces are calculated by using conservation of
mass, momentum and energy equations. This work lays a solid
foundation for future efforts as detailed in [12], including wind tun-
nel tests on the slotted rotor wing which would directly measure the
forces and power generated by rotor blades mounted. A robust de-
sign of the methodology can be implemented for future aircrafts by
not only on this design knowing its performance and efficiency but
also can be utilized for different design parameters [11].
3. Geometric details of the wing
A NACA 4415 airfoil model is used in current design for the turbine
blade mount with the exact radius of the leading edge and for the
effective variation of flow effects capture[7] [11] [8]. The turbine
design enriched the boundary layer by decreasing the drag over the
airfoil. The design adopted in the wing has shown in the figure. 1
representing the chord, upper and lower curve on the airfoil section.
The plan view of the wing is presented in Fig. 2 which clearly states
that the wing plan form is rectangular with 510 x 300 mm2 with the
leading edge radius diameter 120mm as shown in the Fig. 3.
434
International Journal of Engineering & Technology
Fig. 1: NACA 4415 Airfoil Section.
Fig. 2: Top View of the Wing.
Fig. 3: Sectional View of the Airfoil with Dimensions At A-A.
3.1. Geometry of the slotted airfoil
The airfoil used for experimental setup is NACA4415. Slotted wing
with turbine is shown in Fig. 4 with turbine mount plan view and
Fig. 5 showing the blade side view with dimensions in mm. The
experimental analysis is carried out for different angle of attack by
varying the Reynolds number ranging from laminar to turbulent
flow from 0 deg to 30 deg angle of attack.
Fig. 4: Sectional View of the Airfoil with Turbine At A-A.
Fig. 5: Front View of the Turbine with Backward Curved Blades.
4. Methodology
The wing model fabricated as per the tunnel attachments which is
supported at both ends of the extended spar of wing connected to
tunnel walls. The model is mounted in the test section of size 2000
x 600 x 600 mm3 as shown in the Fig. 6, where the maximum speed
can be achieved as 50m/s. As the tunnel is open type with the min-
imum flow disturbances the tests were carried. The flow is consid-
ered to be viscous and incompressible. Further validation of data
and accuracy of the results were investigated by using the projection
manometer focused on the vertical multi manometer tubes. The re-
quired velocity is achieved in the tunnel by the axial flow fan placed
at the end of the tunnel by suction of air from bell mouth entry.
Fig. 6: Low Speed Wind Tunnel Facility
4.1. Power generation
Power is generated by driving the turbine with free stream flow.
This works by renovating the mechanical energy into electrical en-
ergy and the generated power is measured using the induction mo-
tor. The induction works on the principle of electromagnetic induc-
tion from the magnetic field of the stator winding [15] [12]. This
clearly states that induction motor can be built without electrical
connections to the rotor. As an open, drip proof (ODP motor allows
a free air exchange from outside to the inner stator windings, this
style of motor tends to be slightly more efficient because the wind-
ings are cooler [14]. The study suggests that lower the speed the
larger the frame.
4.2. Flow visualization
As air is transparent, it is difficult to observe the dynamic behaviour
of air. As an alternative or substitute, multiple methods of both
quantitative and qualitative flow visualization methods can been
implemented for testing in a wind tunnel.
Tufts and smoke flow visualization techniques are used in the cur-
rent work. Tufts are small length string like structure made of fabric
or any other lightweight [6] [16]. Popular materials for tufts are
made of monofilament nylon, and polyester or cotton No. 60 sew-
ing threads [1] [18]. Surface tufts only give data about the surface
flows in the lowest part of the boundary layer [4]. Encapsulating the
surface patterns to visualize the free stream flow over the model
takes some skills and knowledge.
The airfoil coordinates are selected for maximum lift area. The se-
lected airfoil is mounted with turbine blade according to the dimen-
sions specified in Fig. 1-4. Flow visualization techniques are set for
the wing with tufts. The results at different angles of attack at di-
verse velocity conditions are given in Fig. 13. Smoke flow visuali-
zation test is carried out for airfoil with different angle of attack at
different velocities is carried out for the wing. The obtained results
are shown in the fig. 7 to fig 12. The main objective of the work is
to find the voltage for the turbine motor with slotted wing, the ex-
periment is carried for various angle of attack at different velocity
conditions as given in the following figures from Fig. 9-13.
5. Results and discussions
Experimental results are obtained in two ways one is with flow vis-
ualization and other is to determine the feasibility of voltage gener-
ated by the turbine at various speeds and angle of attack. In case of
flow visualization smoke and tuft grid methods both are taken for
resultant flow distribution and disturbances on the wing. For the
measurement of voltage a dynamo was used and voltage was meas-
ured using a voltmeter for different speeds (16 m/s, 20m/s, 24m/s,
28m/s, 32m/s, 35m/s) as presented in table 1.
International Journal of Engineering & Technology
435
Fig. 7: Side View of the Tufted Airfoil in Wind Tunnel at 0degree AoA.
Fig. 8: Side View of the Tufted Airfoil in Wind Tunnel at 15 Degree AoA.
Fig. 9: Side View of the Tufted Airfoil in Wind Tunnel at 25 Degree AoA.
The streamline flow pattern over the airfoil at 0 degrees AoA in Fig.
7, it’s also known as a laminar flow because of each layer of the
flow stream having the same velocity which doesn’t even get af-
fected by the airfoil at the 0 degrees of AOA. The flow is being
separated at the leading edge of the airfoil at 15 degrees AoA in Fig.
8. As the flow is no longer able to overcome the surface friction
which causes the flow to separate from the body. Side view of the
flow visualization, at 25 degrees of AoA as in Fig. 9, where the flow
is getting separated at the tip of the leading edge, which is always
occurred due to adverse pressure gradient at the surface which led
to the separation of the boundary layer.
The flow visualization was done on a wing to identify the flow be-
haviour at various sections of the wing. Initially, the smoke test (2
m/s) was done on the wing at 0° AoA shown in fig. 10, where in-
vestigation has stated the flow to be streamlined at the surface. But
with change in AoA, the flow started separating at the surface of
the wing. As further increase in AoA is shown in fig.11 and fig 12,
the flow is separated from the leading edge due to the adverse pres-
sure gradient and also found the vortex formation at the corner of
the slotted area and leading edge of the wing. Secondly, the tuft test
was done on the wing to identify the flow behaviour by using
threads which floated freely under the flow.
Fig. 10: Side View of the Stream Lines over Wing at 0 Degree AoA.
Fig. 11: Side View of the Stream Lines over Wing at 15 Degree AoA.
Fig. 12: Side View of the Stream Lines over Wing at 25 Degree AoA.
The tufts placed on the wing as shown in Fig. 7 to Fig. 9 placed in
the wind tunnel at 0 degree AOA is tested at various speeds ranging
from 16-35m/s. Result was found that the threads at the trailing
edge appeared to be straight under the flow which simply indicates
that the flow streamlines. Increase in AoA, has lead the threads at
the surface got twisted due to the reverse flow which has occurred
at the time of separation of the flow at the surface. In the meanwhile,
the threads were merged and got curled and formed like a rope
which indicates the strength of the flow behind the wing trailing
edge induced drag is increased with an angle of attack and at differ-
ent free stream velocity [15] [2].
Table 1: Voltage Generated by Turbine by Variation of Angle of Attack
with Different Speeds
Velocity
Angle of Attack (AoA)
m/s
-15
-20
-25
-30
0
15
20
25
30
16
NR
R
R
R
NR
NR
R
R
R
0
3.8
4.5
3.3
0
0
3.9
4.6
3.4
20
NR
R
R
R
NR
NR
R
R
R
0
4.8
4.9
4.7
0
0
4.9
5
4.8
24
NR
R
R
R
NR
NR
R
R
R
0
4.3
4.9
4.8
0
0
4.3
5.1
4.8
28
NR
R
R
R
NR
NR
R
R
R
0
5.1
5
4.9
0
0
5.2
5.3
4.8
32
NR
R
R
R
NR
NR
R
R
R
0
7.6
7.5
5.1
0
0
7.5
7.6
5.2
35
NR
R
R
R
NR
NR
R
R
R
0
9.4
8.4
5.4
0
0
9.5
8.5
5.5
436
International Journal of Engineering & Technology
Fig. 13: Angle of Attack Increment with Velocity.
Moreover, at the higher AOA, the threads at the trailing edges got
rolled up due to the vortex formation at the corner of the edges [6].
Similarly, the same phenomena occurred at the surface near to the
slotted area of the wing while tested at a higher AOA. This resulting
phenomenon has indicated that the turbine mount at the trailing
edge is not a feasible input.
The turbine mounted on the wing was successfully tested for vari-
ous Reynolds numbers resulting in power generation which is pre-
sented in the Fig.9 states that the power generated from turbine
measured in volts has raised to 10 volts at a speed of 35 m/s with
angle of attack between 20 deg – 25 deg. In the present result the
power is proportional to the angle of attack within the aerodynamic
limits of the geometry of airfoil and the optimized results have been
achieved for the angle of attack of 20 deg.
Further increment in angle of attack resulted in the loss of power at
the turbine compared to the previous limit and can be indicative of
drag increment due to adverse pressure gradient the turbine loses its
energy.
6. Conclusion
In comparison to various tests of flow visualization at various angle
of angle of attack and velocity it is determined that the flow deviates
from the trailing edge resulting in strong trailing edge vortices elu-
cidated the position of the turbine. The turbine blades in this design
is 45 deg angled blades provides the power for the aircraft which
can be utilized in emergency systems if adopted on the aircraft wing.
The power values are investigated on the scaled model if the same
concept is adopted in real aircraft wing this will change the current
requirements of power in flight conditions. Optimal values in this
current design is in between 20 deg to 25 deg angle of attack. Fea-
sibility of this idea did not work for low angle of attack which is
less than 15 deg. As one turbine generates the power of 9.5 volts
this can be increased to the requirements of a hydraulic system to
compensate the need of axial systems for power generation.
Acknowledgement
Authors would like to thank Dr. L V Narasimha Prasad, Director,
IARE, and Management for their continuous research encourage-
ment and support given for the successful completion of this work.
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