YOGESH BABBAR

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COMPUTATIONAL ANALYSIS OF RAM AIR PARACHUTE
CANOPY USING PANEL METHODS

• YOGESH BABBAR
• B.E 3rd year
• Aeronautical Engineering Department
• Punjab Engineering College, Chandigarh

Yogesh Babbar
PEC, Chandigarh
2
Keywords

• Ram Air Parachute
• Parafoil
• Canopy
• Panel Methods
• Coefficient of Lift (CL)
• Coefficient of Lift (CD)
• Coefficient of Pressure (CP)
• CFD

Yogesh Babbar
PEC, Chandigarh
3
Introduction A Ram Air Parachute

• Patented by Jalbert in 1966
• Better maneuverability as compared to drag
  parachute
• Category- Flexible wing aircraft
• Applications- cargo, military, recreation, sports

Yogesh Babbar
PEC, Chandigarh
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Principle of Operation
Yogesh Babbar
PEC, Chandigarh
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Current Research status

• Full parachute research is mainly based on
  experiments
• Work is due in structure canopy interactions.
• Various degree of freedom models are being
  formulated.
• Effect of leading edge cut is being formulated.
• CFD is being used to simulate the flow

Yogesh Babbar
PEC, Chandigarh
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Present Work( A Summary)

• Comparison of CL and CD for the Canopy using
  lifting line theory and Source Panel methods
  based on potential flow theory
• The values of CL from theory have been directly
  compared to the panel code values.
• The comparison between theoretical and Panel Code
  values for CD has been made under two cases
• CASE1 Excluding Skin Friction
• CASE2 Including Skin Friction

Yogesh Babbar
PEC, Chandigarh
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Actual Geometry
Yogesh Babbar
PEC, Chandigarh
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Analyzed Geometry
Yogesh Babbar
PEC, Chandigarh
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Features

• Span 1.224m
• Chord 0.545m
• Radius of Curvature 0.8 span 0.9792m
• Planform area 0.66708 m2
• Aspect Ratio (b2/S) 2.248( low)
• Airfoil section ClarkY 18 thick

Yogesh Babbar
PEC, Chandigarh
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Assumptions

• Flow is assumed to be incompressible.
• The canopy is assumed to be closed at the front.
• The bumps at the surface are assumed to be
  absent.
• The skin friction drag is estimated theoretically
  based on Reynolds number assuming turbulent flow

Yogesh Babbar
PEC, Chandigarh
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Theoretical formulation
Yogesh Babbar
PEC, Chandigarh
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Basic airfoil drag Pressure drag Skin
Friction drag
(30) (70)Total
Basic airfoil drag as given by Lingard0.015
CDo Basic Airfoil Drag
Yogesh Babbar
PEC, Chandigarh
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Panel Code

• Input
• 1. Geometry
• 2. Flow conditions
• Processing
• 1. Create panels on the surface
• 2. Obtain CP for each panel
• 3. Integrate to obtain coefficients
• Output
• Coefficient of Lift (CL)
• Coefficient of Drag (CD)

Yogesh Babbar
PEC, Chandigarh
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CD from Panel Code

• Panel Code cannot account for skin friction drag
• Case I Theoretical value of CD directly compared
  to CD from Panel Code
• Theoretical estimation of skin friction
• Total CD obtained after adding the CD due to skin
  friction
• Case II value of CD compared to new value of CD

Yogesh Babbar
PEC, Chandigarh
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Skin Friction Drag (Theoretical Estimation)
This value of skin friction drag is added to the
CD from panel code to get the total CD which can
be compared to the CD from theory( CASE II)
Yogesh Babbar
PEC, Chandigarh
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Results Color Plots for CL
Angle of attack0o Angle of Side
Slip0o Angle of attack10o Angle of Side
Slip0o Angle of attack0o Angle of Side
Slip6o
Color Bar
Yogesh Babbar
PEC, Chandigarh
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Coefficient of Lift (CL)
Yogesh Babbar
PEC, Chandigarh
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Coefficient of Drag( CD)CASE I( Excluding Skin
friction Drag)
Yogesh Babbar
PEC, Chandigarh
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Coefficient of Drag( CD)CASE II( Including Skin
friction Drag)
Yogesh Babbar
PEC, Chandigarh
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Highlights and Conclusions

• The theoretical and computational CD Vs a curves
  diverge at high angles of attack
• Theoretical Values in CASE I and CASE II differ
  be a constant value of 0.0105.
• Computational Values of CASE I and CASE II differ
  be a constant value of 0.0108
• The good agreement in the comparison is subjected
  to the assumption( Pressure drag 30 of Basic
  Airfoil drag)
• This analysis has limitations of being used in a
  limited number of cases.

Yogesh Babbar
PEC, Chandigarh
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CFD Results( The Real Parachute)
Flow Conditions Angle of attack
5o Angle of side slip 0o Free stream
velocity 12 m /s
CL0.435 ( 0.5 from panel code) CD0.15 ( 0.05
from Panel code) Possible reasons for
variation LE cut, Bumps, Turbulence,
Yogesh Babbar
PEC, Chandigarh
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Future Work

• Work is underway for analyzing a 3-DoF model of
  Parafoil Payload system
• CFD work is underway for analyzing more realistic
  conditions
• Structure Canopy interactions can be further
  investigated
• Effect of Leading Edge cut can be further
  investigated
• CFD can also be utilized for a completer higher
  degree of freedom models.

Yogesh Babbar
PEC, Chandigarh
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References

• Lingard J. S, (1995) Ram Air Parachute Design,
  13th AIAA Aerodynamic Decelerator Conference,
  Clearwater Beach.
• Nicolaides JD, Speelman III RJ, Menard GLC. A
  review of parafoil applications. Journal of
  Aircraft Vol7 no 5, pp 423-431.
• Aliabadi SK, Garrard WL, Kalro V, Mittal S,
  Tezduyar TE, Stein KR. (1995)Parallel finite
  element computations of the dynamics of large ram
  air parachutes. AIAA Paper 95-1581, 13th
  Aerodynamic Decelerator and Systems 33rd
  conference, Clearwater, FL, 278293.
• Fundamentals of aerodynamics by J. D. Anderson
  Jr., McGraw-Hill,3rd edition, New York.
• Joshua Aaron Bowman, Determinations of Parafoil
  lift and drag coefficients using both three
  dimensional modeling and experimental methods by,
  Graduate College, Iowa State university, USA.
• Om Prakash, (2003) Aerodynamics and Longitudional
  Stability of Parafoil Payload system,Department
  of Aerospace Engineering, Indian Institute of
  Technology Bombay, Mumbai, India

Yogesh Babbar
PEC, Chandigarh
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Thank You
Questions Please!
Yogesh Babbar B.E. 3rd Year Dept. of Aeronautical
Engineering Punjab Engineering College Chandigarh
yogeshbabbar_at_gmail.com