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Results for “nonpropulsive noise”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Airframe noise measurements on a transport model in a quiet flow facility

An experimental investigation was conducted in an anechoic flow facility to explore problems and methods of measuring the airframe (nonpropulsive) noise associated with a 1/20-scale model of a B-737 transport. The test model geometry simulated the cruise and a landing configuration. Nonpropulsive model noise was detected at various flow velocities and at various angles of attack when turbulent flow was induced over the model. Discrete tones, associated with the extended undercarriage and wheel cavities, and an increase in broadband sound pressure level were observed with the model in a landing configuration.

Shearin, J. G.↗
NASA NTRS1975

A preliminary investigation of remotely piloted vehicles for airframe noise research

Aircraft noise encountered in the community is caused predominantly by the aircraft engines. However, expected advances in engine noise technology combined with recent experimental evidence indicate that airframe (nonpropulsive) noise, may be a significant aircraft noise component in the future. Thus, methods for research into control of this type of noise are being evaluated and a technique based on the remotely piloted vehicle (RPV) concept appears to overcome some of the difficulties encountered with other test techniques. In particular, this paper presents sample experimental data, gathered during a preliminary RPV experiment, which illustrate the high signal-to-noise ratio attainable with this technique. Further, since the data are recorded as transients or nonstationary signals, a method of measurement and analysis is presented which increases statistical confidence in the results.

Fratello, D. J.↗
NASA NTRS1991

Airframe Noise

Current understanding of airframe noise was reviewed as represented by experiment at model and full scale, by theoretical modeling, and by empirical correlation models. The principal component sources are associated with the trailing edges of wing and tail, deflected trailing edge flaps, flap side edges, leading edge flaps or slats, undercarriage gear elements, gear wheel wells, fuselage and wing boundary layers, and panel vibration, together with many minor protrusions like radio antennas and air conditioning intakes which may contribute significantly to perceived noise. There are also possibilities for interactions between the various mechanisms. With current engine technology, the principal airframe noise mechanisms dominate only at low frequencies, typically less than 1 kHz and often much lower, but further reduction of turbomachinery noise in particular may make airframe noise the principal element of approach noise at frequencies in the sensitive range.

Trailing-Edge↗
NASA NTRS1975

Advanced short haul systems in high density markets

The design requirements, performance, economics, and noise aspects of STOL and VTOL conceptual aircraft developed for short haul air transportation are reviewed, along with the characteristics of areas of high-density annual passenger flow in which the aircraft are intended to operate. It is shown that aircraft of 100 to 200 passenger capacity provide the best return on investment in high density markets. The various STOL propulsive lift concepts have the same general trends with field length; their wing loadings are 20 to 30 pounds per square foot higher than the nonpropulsive lift concepts. A comparison of the aircraft under consideration shows that no one aircraft concept will be optimum for all future operational environments.

Galloway, T. L.↗