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*UNSTEADY AEROFOIL AERODYNAMICS

Purpose

To specify the unsteady aerodynamic modeling options.

Theory

Refer to Unsteady Aerodynamics in the AeroDyn program documentation for further information.

Keyword Format

Two lines of data, defining Beddoes Leishmann options as follows:

AOA34=AoA34

UA_MOD=Unsteady Model

FLOOKUP=Separation Distance Lookup

UAStartRad=Starting rotor radius for dynamic stall (fraction)

UAEndRad=Ending rotor radius for dynamic stall (fraction)

 

 

AoA34 determines whether the baseline angle of attack is sampled at the 3/4 chord or at the aerodynamic center point. Most unsteady aerodynamic models will require AoA34 to be set to TRUE. But when using quasi-steady aerodynamics, you may wish to set it to TRUE or FALSE.

Unsteady Model can be QUASI-STEADY (no unsteady aerofoil aerodynamics), BEDDOES-LEISHMANN GONZALEZ (the extensions to Beddoes-Leishman model developed by González), BEDDOES-LEISHMANN MINEMMA/PIERCE (the extensions to Beddoes-Leishman developed by Minnema/Pierce), BEDDOES-LEISHMANN HGM 4 STATES (4-states continuous-time Beddoes-Leishman model developed by Hansen, Gaunna, and Madsen), BEDDOES-LEISHMANN HGM+VORTEX 5 STATES (5-states continuous-time Beddoes-Leishman model similar to Hansen, Gaunna, and Madsen with an additional state for vortex generation), OYE (1-state continuous-time developed by Oye) or BOEING-VERTOL (discrete-time Boeing-Vertol model).

Separation Distance Lookup determines how the nondimensional separation distance value, f’, will be calculated. When Separation Distance Lookup is set to 1, f’ is determined via a lookup into the static lift-force coefficient and drag-force coefficient data. Note that Separation Distance Lookup must be 1 in this version of AeroDyn (v15.02.04).

UAStartRad is the starting rotor radius where dynamic stall will be turned on. Enter a number between 0 and 1, representing a fraction of rotor radius, to indicate where unsteady aerodynamics should begin turning on. If omitted, it defaults to 0 (the blade root). All blade nodes that are located at a rotor radius less than UAStartRad will have unsteady aerodynamics turned off for the entire simulation.

UAEndRad is the ending rotor radius where dynamic stall will be turned on. Enter a number between 0 and 1, representing a fraction of rotor radius, to indicate the last rotor radius where unsteady aerodynamics should be turned on. If omitted, it defaults to 1 (the blade tip). All blade nodes that are located at a rotor radius greater than UAEndRad will have unsteady aerodynamics turned off for the entire simulation.

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