Effect of struts on aeroacoustics of axisymmetric supersonic inlets

A study was conducted to determine the effect of strut position on the aerodynamic and acoustic performance of a supersonic inlet. The investigated inlet was a prototype 1/14 scale model of a mixed compression, axisymmetric supersonic inlet designed for the high speed civil transport aircraft. A 10.4 cm (4.1 in.) turbofan engine simulator was used in conjunction with the inlet to provide the typical noise signature of a high bypass turbofan engine. Two inlet configurations were investigated in this study. The first configuration was the standard inlet design where the struts are located immediately upstream of the fan. The new configuration has the struts located 3.3 chord length upstream of the fan. The purpose for relocating the strut position was to reduce the flow distortion and radiated noise level. The experiment was conducted at various fan operating conditions in order to simulate aircraft approach. The inlet was tested statically without simulating the inflight speed effects. Steady state measurements were made in order to evaluate the aerodynamic performance of the inlet. The aerodynamic results show that the movement of the struts to a new location allowed the strut wake to diffuse significantly before reaching the fan. This reduced the circumferential distortion parameter by a factor of 2.4, without affecting the pressure recovery of the inlet at a fan Abstract speed of 30,000 rpm (40 PNC). Acoustic measurements were taken in the far field in the 0°-110°sector from the inlet axis. The new configuration of the inlet showed an improved acoustic performance over the standard design. Relocating the struts upstream reduced the blade passing tone by an average of 8 dB (0°-110°) sector, and the overall sound pressure level was lowered by an average of 2.6 dB at a fan speed of 30,000 rpm (40 PNC).

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

1994

Author dc:creator

• Pande, Abhijit

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-07292009-090449

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/43999