Pressure Tap Locations of a DU96W180 airfoil

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Pressure Tap Locationsof a DU96-W-180 airfoil

• Cesar Moreno
• 11/14/2006

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Algorithm (1)

• Overview
• Load airfoil outline and Cp data
• Eliminate x locations where a tap cannot be
  placed
• From x.85c to xc (y and Cp are modified
  accordingly)
• Calculate coefficient of lift after truncation,
• Choose tap locations based on regional spacing
• Each Cp curve is divided into 3 regions, each
  region contains a user-defined number of taps to
  be distributed in an optimized region length
• Calculate coefficient of lift after selection of
  tap locations,

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Algorithm (2)

• Calculate error for each Cp curve at the given
  alpha

coefficient of lift from Cp curve with all data
points
coefficient of lift after data truncation and
tap selection
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Regional Spacing

• Naming convention
• x_i x denotes weight, taps or length and i
  denotes the region
• Weights on upper side w1, w2
• w3 1 w1 w2
• L1 w1efl
• L2 w2efl
• L3 w3efl
• Taps on upper side T1, T2
• T3 max number of taps T1 T2
• Lower side follows the same convention as upper
  side

Region 2
Region 1
Region 3
L1
L2
L3
L4
L5
L6
Region 4
Region 5
Region 6
Effective length, efl.84c
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Optimization
The following objective function was minimized
100 combinations of T1, T2, T4, T5 were used
10 tap combinations on upper side 9,14 10,13
11,12 12,11 13,10 14,9 15,8 16,7 17,6 18,5
10 tap combinations on lower side 9,14 10,13
11,12 12,11 13,10 14,9 15,8 16,7 17,6 18,5
where T1, T2, T4, T5 are fixed
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Results
Percent errors at each alpha for the optimized
configuration
w10.4178, w20.4367, w40.452473, w50.4475
t118, t25, t412, t511
The resulting objective function value was 1.55
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Cp vs. x max Error, alpha 5 deg (1)
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Cp vs. x max Error, alpha 5 deg (2)
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Cp vs. x max Error, alpha 5 deg (3)
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Cp vs. x min Error, alpha 8 deg (1)
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Cp vs. x min Error, alpha 8 deg (2)
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Cp vs. x min Error, alpha 8 deg (3)