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Measurements of the free stream fluctuations above a turbulent boundary layer
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Wood, David H. Westphal, Russell V. |
| Copyright Year | 1987 |
| Description | This paper investigates the velocity fluctuations in the free stream above an incompressible turbulent boundary layer developing at constant pressure. It is assumed that the fluctuations receive contributions from three statistically independent sources: (1) one-dimensional unsteadiness, (2) free stream turbulence, and (3) the potential motion induced by the turbulent boundary layer. Measurements were made in a wind tunnel with a root-mean-square level of the axial velocity fluctuations of about 0.2 percent. All three velocity components were measured using an X-wire probe. The unsteadiness was determined from the spanwise covariance of the axial velocity, measured using two single wire probes. The results show that it is possible to separate the contributions to the r.m.s. level of the velocity fluctuations, without resorting to the dubious technique of high-pass filtering. The separation could be extended to the spectral densities of the contributions, if measurements of sufficient accuracy were available. The Appendix provides a general guide for the measurement of small free stream fluctuation levels. |
| File Size | 1383123 |
| Page Count | 30 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19880004939 |
| Archival Resource Key | ark:/13960/t3b04213z |
| Language | English |
| Publisher Date | 1987-11-01 |
| Access Restriction | Open |
| Subject Keyword | Fluid Mechanics And Heat Transfer Root-mean-square Errors Incompressible Flow Turbulence Fluctuation Theory Wind Tunnel Tests Turbulent Boundary Layer Free Flow Velocity Boundary Layers Axial Flow 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 |
