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Fluid mechanics mechanisms in the stall process of helicopters
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Young Jr., W. H. |
| Copyright Year | 1981 |
| Description | Recent experimental results from airfoils in the Mach number, Reynolds number, or reduced frequency ranges typical of helicopter rotor blades have identified the most influential flow mechanisms in the dynamic stall process. The importance of secondary shed vortices, downstream wake action, and the flow in the separated region is generally acknowledged but poorly understood. By means of surface pressure cross-correlations and flow field measurements in static stall, several new hypotheses have been generated. It is proposed that vortex shedding may be caused by acoustic disturbances propagating forward in the lower (pressure) surface boundary layer, that wake closure is a misnomer, and that the shed vortex leaves a trail of vorticity that forms a turbulent free shear layer. The known dynamic stall flow mechanisms are reviewed and the potential importance of recently proposed and hypothetical flow phenomena with respect to helicopter blade aeroelastic response are assessed. |
| File Size | 2681930 |
| Page Count | 11 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19810012498 |
| Archival Resource Key | ark:/13960/t3mw7807h |
| Language | English |
| Publisher Date | 1981-03-01 |
| Access Restriction | Open |
| Subject Keyword | Aerodynamics Air Flow Vortex Shedding Helicopters Flow Distribution Downwash Rotor Aerodynamics Aeroelasticity Pressure Aerodynamic Stalling Helicopter Wakes Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
