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Turbulence measurements in the near field of a wingtip vortex
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Bradshaw, Peter Zilliac, Greg Chow, Jim |
| Copyright Year | 1997 |
| Description | The roll-up of a wingtip vortex, at Reynolds number based on chord of 4.6 million was studied with an emphasis on suction side and near wake measurements. The research was conducted in a 32 in. x 48 in. low-speed wind tunnel. The half-wing model had a semi-span of 36 in. a chord of 48 in. and a rounded tip. Seven-hole pressure probe measurements of the velocity field surrounding the wingtip showed that a large axial velocity of up to 1.77 U(sub infinity) developed in the vortex core. This level of axial velocity has not been previously measured. Triple-wire probes have been used to measure all components of the Reynolds stress tensor. It was determined from correlation measurements that meandering of the vortex was small and did not appreciably contribute to the turbulence measurements. The flow was found to be turbulent in the near-field (as high as 24 percent RMS w - velocity on the edge of the core) and the turbulence decayed quickly with streamwise distance because of the nearly solid body rotation of the vortex core mean flow. A streamwise variation of the location of peak levels of turbulence, relative to the core centerline, was also found. Close to the trailing edge of the wing, the peak shear stress levels were found at the edge of the vortex core, whereas in the most downstream wake planes they occurred at a radius roughly equal to one-third of the vortex core radius. The Reynolds shear stresses were not aligned with the mean strain rate, indicating that an isotropic-eddy-viscosity based prediction method cannot accurately model the turbulence in the cortex. In cylindrical coordinates, with the origin at the vortex centerline, the radial normal stress was found to be larger than the circumferential. |
| File Size | 90405553 |
| Page Count | 261 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19970011348 |
| Archival Resource Key | ark:/13960/t7dr7sg1z |
| Language | English |
| Publisher Date | 1997-02-01 |
| Access Restriction | Open |
| Subject Keyword | Aeronautics (general) Pressure Sensors Stress Tensors Turbulent Flow Flow Measurement Wing Tips Velocity Distribution Eddy Viscosity Reynolds Stress Isotropy Core Flow Vortices Trailing Edges Near Fields Wind Tunnel Tests Shear Stress Pressure Measurement Wing Loading Strain Rate Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
