We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Editörden.
- Authors
Güven, Ismail
- Abstract
The use of boundary-layer-ingesting, embedded propulsion systems can result in inlet flow distortions where the interaction of the boundaiy-layer vorticity and the inlet lip causes horseshoe vortex formation and the ingestion of streamwise vortices into the inlet. A previously-developed body-force-based fan modeling approach was used to assess the change in fan rotor shock noise generation and propagation in a boundary-layer-ingest-ing, serpentine inlet. This approach is employed here in a parametric study to assess the effects of inlet geometry parameters (offset-to-diameter ratio and downstream-to-upstream area ratio) onflow distortion and rotor shock noise. Mechanisms related to the vortical inlet structures were found to govern changes in the rotor shock noise generation and propagation. The vortex whose circulation is in the opposite direction to the fan rota-tion (counter-swirling vortex) increases incidence angles on the fan blades near the tip, enhancing noise generation. The vortex with circulation in the direction of fan rotation (co-swirling vortex) creates a region of subsonic relative flow near the blade tip radius that decreases the sound power propagated to the far-field. The parametric study revealed that the overall sound power level at the fan leading edge is set by the ingested streamwise circulation, and that for inlet designs in which the streamwise vortices are displaced away from the duct wall, the sound power at the upstream inlet plane increased by as much as 9 dB. By comparing the far-field noise results obtained to those for a con-ventional inlet, it is deduced that the changes in rotor shock noise are predominantly due to the ingestion of streamwise vorticity.
- Subjects
PROPULSION systems; BOUNDARY layer (Aerodynamics); ROTORS; PARAMETER estimation; SWIRLING flow; VORTEX motion
- Publication
Journal of Faculty of Educational Sciences, 2012, Vol 45, Issue 2, p1
- ISSN
1301-3718
- Publication type
Article