AIAA CFD 4^th Drag Prediction Workshop

June 2009, San Antonio, TX

 

22 December 2008

 

Note:  The Configuration Geometry, Test Cases, and Gridding Guidelines are current as of 22 December 2008, but are subject to changes as developments require.   Please check the website periodically for updates http://aiaa-dpw.larc.nasa.gov/, and/or register with dpw@cessna.textron.com to be notified directly.

 

Test Cases: NASA Common Research Model (CRM)

Case 1 – Grid Convergence and Downwash Studies:

1.     Grid Convergence study at Mach = 0.85, C_L = 0.500 (±0.001)
- Tail Incidence angle= 0°
- Coarse, Medium, Fine, Extra-Fine Grids (Extra-Fine grid is optional)
- Chord Reynolds Number 5x10⁶ based on c_REF = 275.80 in

- Reference Temperature = 100°F

2.     Downwash Study at Mach = 0.85
- Drag Polars for alpha = 0.0°, 1.0°, 1.5°, 2.0°, 2.5°, 3.0°, 4.0°
- Tail Incidence angles i_H = -2°, 0°, +2°, and Tail off
- Medium grid
- Chord Reynolds Number 5x10⁶ based on c_REF = 275.80 in

- Reference Temperature = 100°F

- Trimmed Drag Polar (CG at reference center) derived from polars at i_H = -2°, 0°, +2°
- Delta Drag Polar of tail off vs. tail on (i.e. WB vs. WBH trimmed)

- Moment reference center is x_REF = 1325.90 in, z_REF = 177.95 in

Case 2 (Optional) – Mach Sweep Study:

Drag Polars at:
- Mach = 0.70, 0.75, 0.80, 0.83, 0.85, 0.86, 0.87
- Drag Rise curves at C_L = 0.400, 0.450, 0.500 (±0.001 or extracted from polars)
- Untrimmed, Tail Incidence angle, i_H = 0°

- Medium grid
- Chord Reynolds Number 5x10⁶ based on c_REF = 275.80 in

- Reference Temperature = 100°F

Case 3 (Optional) – Reynolds Number Study:

Reynolds Number study at Mach = 0.85, C_L = 0.500 (±0.001)
- Tail Incidence angle i_H = 0°
- Medium grid
- Compare Rn = 5x10⁶ results with Rn =  20x10⁶ results based on c_REF  = 275.80 in

- For Rn = 20x10⁶, Reference Temperature =  -250°F

Notes:

·       Reference Geometry:

o   S_REF= 594,720 in² (4130 ft²)

o   c_REF= 275.80 in

o   x_REF= 1325.90 in

o   z_REF= 177.95

o   AR= 9.0

·       Geometry Reference:

o   JC Vassberg, MA DeHaan, SM Rivers, and RA Wahls, “Development of a Common Research Model for Applied CFD Validation Studies,” AIAA Paper 2008-6919, AIAA Applied Aerodynamics Conference, Honolulu, HI, August, 2008.

·       Simulations are to be “free air”; no wind tunnel walls or model support systems are to be included.

·       Boundary layer is to be fully turbulent.

·       For the optional case 2, interpolated forces and moments are acceptable (as is typically done for wind tunnel data reduction).