Reduced fan noise radiation from a supersonic inlet

A series of experiments was conducted to evaluate the aerodynamic and acoustic performance of a supersonic inlet with a modified auxiliary door geometry. A 1/14 scale model of an axisymmetric, mixed-compression, supersonic inlet designed for civil transportation was used in conjunction with a 10.4cm (4.1 in.) turbofan engine simulator to test a new inlet door geometry designed to reduce flow distortion and noise radiation. The new door geometry uses door passages with increased circumferential span to improve the distribution of the flow entering through the doors. In addition, the new design employs sonic flow velocity at the inlet throat and a converging flow passage in the auxiliary doors to attenuate propagating fan noise through the choking effect. To provide a basis for comparison, a baseline door geometry representative of current designs was also tested. The experiments were conducted at simulated aircraft takeoff engine speeds under static conditions. Steady-state measurements of the inlet flow field were made along with far field acoustic measurements of the fan noise. The results show the new door geometry is successful in reducing circumferential flow distortion at the fan entrance by a factor of 2.3 compared to the baseline configuration. In addition, far field radiation of the blade passing frequency tone and overall noise is reduced by an average of 4dB(SPL) in the forward and aft sectors (0° to 110° from the inlet axis). As a compromise for the distortion and acoustic improvements, the overall inlet total pressure recovery is reduced by approximately 2% with the new auxiliary doors.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Mechanical Engineering

Department dc:contributor.department

Mechanical Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1993

Author dc:creator

• Detwiler, Kevin P.

Chair dc:contributor.committeechair

• Ng, Wing Fai

Committee members dc:contributor.committeemember

• Burdisso, Ricardo A.
• Leonard, Robert G.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-09192009-040457

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/44869