Some experimental observations of the law of the wall behind large eddy breakup devices using servo-controlled skin friction balances
Abstract
Changes in the law of the wall in a zero pressure gradient boundary layer caused by altering the flow pattern with large eddy breakup (LEBU) devices are investigated. Among the initial configurations tested are single and triple ribbon devices placed parallel to the surface at different positions inside the boundary layer. Measurements are made of skin friction using servo-controlled balances, and a description is given of these instruments. The data reveal that both the skin friction and the law of the wall can be substantially influenced by the presence and position of the ribbons. For a given three-ribbon configuration, reductions as high as 35 percent are registered by the balances just downstream of the LEBU. Significant departures from the 'universal' log law are observed behind the LEBU, and the apparent wall law similarity is reestablished approximately 15 to 20 boundary layer thicknesses downstream.
- Publication:
-
AIAA, Aerospace Sciences Meeting
- Pub Date:
- January 1984
- Bibcode:
- 1984aiaa.meetQ....N
- Keywords:
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- Aerodynamic Balance;
- Drag Reduction;
- Skin Friction;
- Vortices;
- Wall Flow;
- Ribbons;
- Servocontrol;
- Wind Tunnel Tests;
- Fluid Mechanics and Heat Transfer