Fan noise reduction from a supersonic inlet during simulated aircraft approach

Journal Article · Sat Apr 01 04:00:00 EST 1995 · Journal of Engineering for Gas Turbines and Power

DOI:https://doi.org/10.1115/1.2814086· OSTI ID:78170

Nuckolls, W E; Ng, W F ^[1]

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1. Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States). Dept. of Mechanical Engineering

A series of experiments was conducted to investigate the radiation of fan noise from a supersonic inlet during a simulated aircraft approach. A scaled-down model of an axisymmetric, mixed-compression, supersonic inlet (P-inlet) was used in conjunction with a 10.4 cm (4.1 in) diameter turbofan engine simulator as the noise source. The tests were conducted at an outdoor facility under static conditions. The main goal of the experiment was to reduce the forward radiating fan noise by modifying the auxiliary inlet doors. The modified doors are designed to reduce the inlet distortion to the fan face. In addition, the new door design also uses a converging flow passage in order to take advantage of the noise attenuation due to the choking effect at the auxiliary door. The simulator was tested at 60 percent design speed in an attempt to match the simulator noise source to that of a real aircraft engine on approach. Both aerodynamic and acoustic measurements were taken in the experiments. The results show that when compared to the original design, the modified auxiliary inlet doors reduced the circumferential inlet distortion to the fan face by a factor of two. The key result is that the blade passing frequency tone has been decreased by an average of 6dB in the forward sector for the modified door design. Results from the closed auxiliary inlet door case are also presented to provide additional comparisons.

• Sponsoring Organization: USDOE
• OSTI ID: 78170
• Report Number(s): CONF-930502--
• Journal Information: Journal of Engineering for Gas Turbines and Power, Journal Name: Journal of Engineering for Gas Turbines and Power Journal Issue: 2 Vol. 117; ISSN JETPEZ; ISSN 0742-4795
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
BLOWERS
GAS TURBINE ENGINES
NOISE POLLUTION ABATEMENT
SUPERSONIC FLOW
TURBOFAN ENGINES