Abstract
An experimental investigation was conducted on the performance and boundary layer characteristics of the Wortmann FX 63-137 airfoil with and without trip wire roughness. Data were obtained through use of a three-component strain gage force balance and static pressure measurement equipment at a test Reynolds number of R c = 100,000. Emphasis was placed on determining the effect of trip wire placement and size on such performance parameters as (C l /C d )max and (C 3/2 l /C d )max. Prediction of transition location by the criterion due to Tani and Gibbings was found to have limited application. Most trip wire locations resulted in degraded performance, but for some locations, minimum drag was reduced, maximum lift to drag ratio increased, and hysteresis averted.
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Abbreviations
- C d :
-
airfoil sectional drag coefficient
- C l :
-
airfoil sectional lift coefficient
- C lα :
-
airfoil sectional lift curve slope coefficient
- C m c/4 :
-
airfoil sectional moment coefficient measured about the quarter-chord location
- C p :
-
pressure coefficient
- c :
-
chord length of airfoil model
- k :
-
roughness height
- R :
-
refers to the occurrence of reattachment
- R c :
-
Reynolds number based on chord c
- S :
-
refers to the occurrence of laminar separation
- S′ :
-
refers to occurrence of turbulent separation
- s :
-
arclength distance from stagnation point
- T :
-
refers to occurrence of transition
- U :
-
flow velocity
- w :
-
roughness width
- x :
-
distance along chord line
- α:
-
angle to attack
- δ1 :
-
boundary layer displacement thickness
- Λ1 :
-
pressure gradient parameter defined as δ1 (dU/ds)]/ν
- ν:
-
kinematic viscosity
- cr:
-
refers to critical value for some effect on transition
- e :
-
refers to velocity external to the boundary layer at a particular location
- k :
-
pertains to roughness height or location
- max:
-
refers to the maximum value of a parameter
- min:
-
refers to the minimum value of some parameter
- p :
-
static pressure
- t :
-
pertains to the location of transition
References
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Huber, A.F., Mueller, T.J. The effect of trip wire roughness on the performance of the Wortmann FX 63-137 airfoil at low Reynolds numbers. Experiments in Fluids 5, 263–272 (1987). https://doi.org/10.1007/BF00279740
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DOI: https://doi.org/10.1007/BF00279740