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Manning, J. C.

Publications and source records attributed to Manning, J. C..

15 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Far-field acoustics of supersonic rectangular nozzles with various throat aspect ratios

The far-field acoustic behavior of supersonic jets produced by four rectangular nozzles with various throat aspect ratios are reported. One nozzle tested was designed for an exit Mach number of 1.66 with throat aspect ratio of 2.0. The remaining three nozzles (throat aspect ratios of 3.7, 5.8, 7.6) were designed for an exit Mach number of 1.35. Acoustic results presented include narrowband spectra and overall sound pressures for numerous operating pressure ratios and spatial locations.

Ponton, M. K.↗
NASA NTRS1986

The preferred spatial mode of instability for a Mach 2 jet

Phase-averaged schlieren video and an array of azimuthally oriented microphones were used in the experiments performed to determine the preferred spatial structure associated with supersonic nozzle design for an exhaust Mach number of 2. The jet flow was unheated, chemically inert, and submerged in a static environment, conditions that are satisfactory for the quasi-linear wave-analytical model of Tam and Morris (1980) and Tam and Burton (1984). For general conditions of undeterminate phase-averaged optical records, a conditional sampling method was devised, based on fundamental multimode components. This method uncovers the preferred spatial structure, and shows that in addition to the dominant jet flapping mode, there is also a significant contribution from the axisymmetric mode. Near-field correlations with a moving microphone indicate that the flapping plane is nearly stationary, and not spinning as in the Westley and Wolley (1975) experiment.

Seiner, J. M.↗
NASA NTRS1986

Acoustic properties associated with rectangular geometry supersonic nozzles

Acoustic property experiments have been conducted to ascertain the behavior of rectangular geometry supersonic nozzles whose throat aspect ratios vary over a 2.0-7.6 range, and whose three partial sidewall geometries range from full to 75-percent cutback. The tests employed unheated air at static conditions for nozzle Mach numbers of 1.35-1.66. It is found that sonic fatigue failures are possible at certain partial sidewall geometries and high nozzle aspect ratios. Unlike axisymmetric supersonic nozzles, shock noise dominates both the rear and forward arc for throat aspect ratio cases greater than 5.6. Jet screech frequency was adequately predicted with a simple vortex sheel model.

Seiner, J. M.↗
NASA NTRS1986

Dynamic pressure loads associated with twin supersonic plume resonance

The phenomenon of twin supersonic plume resonance is defined and studied as it pertains to high level dynamic loads in the inter-nozzle region of aircraft like the F-15 and B1-A. Using a 1/40th scale model twin jet nacelle with powered choked nozzles, it is found that intense internozzle dynamic pressures are associated with the synchrophased coupling of each plume's jet flapping mode. This condition is found most prevalent when each plume's jet flapping mode has constituent elements composed of the B-type helical instability. Suppression of these fatigue bearing loads was accomplished by simple geometric modifications to only one plume's nozzle. These modifications disrupt the natural selection of the B-type mode and thereby decouple the plumes.

Seiner, J. M.↗
NASA NTRS1986

Miniature Microphone Adapter

New microphone adapter permits installation of commercially available condenser microphone 1/8 inch (3 mm) in diameter at location of sensing ports, with remotely located preamplifier. Microphone has high-impedance source and low-level electrical output signal; therfore, adapter designed with minimum capacitance to avoid degradation of microphone sensitivity. Probe insensitive to aeroacoustic disturbances in high-velocity flow.

Manning, J. C.↗
NASA NTRS1983

Aeroacoustic research facilities at NASA Langley Research Center: Description and operational characteristics

A number of facilities were developed which provide unique test capabilities for aeroacoustic research. Information regarding physical layouts, dimensions, construction features, and operating capabilities of these facilities is compiled. Possible research applications include the behavior of such noise sources as jets, rotors, and propellers in simulated forward motion; studies of noise due to the interactions of aerodynamic flows with solid surfaces and bodies; sound propagation in ducts with airflow; and the evaluation of acoustical materials.

Hubbard, H. H.↗
NASA NTRS1977

Noise reduction evaluation of grids in a supersonic air stream with application to Space Shuttle

Near field acoustic measurements were obtained for a model supersonic air jet perturbed by a screen. Noise reduction potential in the vicinity of the space shuttle vehicle during ground launch when the rocket exhaust flow is perturbed by a grid was determined. Both 10 and 12 mesh screens were utilized for this experiment, and each exhibited a noise reduction only at very low frequencies in the near field forward arc. A power spectrum analysis revealed that a modest reduction of from 3 to 5 decibels exists below a Strouhal number S sub t = 0.11. Above S sub t = 0.11 screen harmonics increased the observed sound pressure level. The favorable noise reductions obtained with screens for S sub t 0.11 may be of substantial interest for the space shuttle at ground launch.

Seiner, J. M.↗
NASA NTRS1976

Measured response of a complex structure to supersonic turbulent boundary layers

Measurements of the response of a large frame-stringer panel excited by supersonic turbulent boundary layer are reported. The statistical description of the wall pressure fluctuations in terms of the mean flow parameters governing the turbulent boundary layer is given. These results can be used in the development of design criteria on the response of sidewall structure of a large airplane in supersonic flight, since both forcing field and structure are realistic. Results indicate the significant importance of the modal coupling and the acoustic damping. The acoustic damping plays a major role in the response of the structure.

Maestrello, L.↗
NASA NTRS1972

Wind velocity profiles measured by the smoke-trail method at Wallops Island, Virginia, 1965 - 1969

Thirty-nine detailed wind profiles measured by the smoke-trail method at the Wallops Island Test Range during the years 1965 through 1969 are presented as west-to-east and south-to-north velocity components at height intervals of 25 meters. The overall altitude range of the wind profile data varies from about 1 to 23 km. The wind measurements, which were made under a variety of conditions, include velocities in excess of the annual 99-percent highest wind value (the wind value which will not be exceeded 99 percent of the time) for the Wallops Island Test Range. The report also includes a listing of the wind soundings and their maximum velocities and direction of the maximum velocities measured at Wallops Island from 1959 through 1969. Results of smoke-trail enhancement experiments are also indicated.

Rhyne, R. H.↗
NASA NTRS1972

Wind velocity profiles measured by the smoke-trail method at the Eastern Test Range, 1964

Twenty-six detailed wind profiles measured by the smoke trail technique at the Eastern Test Range during the first seven months of 1964 are presented as plots of west-to-east and south-to-north velocity components at height intervals of 25 meters. The overall altitude ranges of the profiles vary from about 2.6 to 19.1 km. The wind measurements, which were made under a variety of conditions, include velocities in excess of the 90- and 95-percent highest values for the Eastern Test Range. The report also includes a listing of the wind profiles, their maximum velocities and direction of the maximum velocities, measured by the smoke trail method at the Eastern Test Range from 1962 to 1964.

Manning, J. C.↗