Performance Of Baffle Research Articles

The use of an array receiver in baffle performance measurements

The use of an array receiver in place of the omniphone traditionally employed in baffle performance measurements can reduce panel edge diffraction interference as well as provide a measurement which averages over any field nonuniformities caused by panel inhomogeneities (e.g., tile edges and vacuum channels). In addition, boundary reflections and ambient noise can be suppressed. In this paper, data obtained from some recent experiments employing a planar array as a receiver is discussed. The predictions of theoretical models for baffle performance and panel edge diffraction are compared with the experimental results. [Work supported by NUSC, New London, CT.]

The use of an array receiver in baffle performance measurements

The use of an array receiver in place of the omniphone traditionally employed in baffle performance measurements can reduce panel edge diffraction interference as well as provide a measurement which averages over any field nonuniformities caused by panel inhomogeneities (e.g., tile edges and vacuum channels). In addition, boundary reflections and ambient noise can be suppressed. In this paper, data obtained from some recent experiments employing a planar array as a receiver is discussed. The predictions of theoretical models for baffle performance and panel edge diffraction are compared with the experimental results. [Work supported by NUSC, New London, CT.]

Edge diffraction interference in baffle performance measurements

Edge diffraction has usually been a limiting interference mechanism in baffle performance measurements. In this paper, Kendig's theory of diffraction by an impedance‐covered half‐plane [R. P. Kendig, Ph.D. thesis, Pennsylvania State University (1977)] is used to generate predictions of edge diffraction interference levels for baffles with general surface impedances. The effectiveness of an array receiver for reducing the interference is discussed.

Analysis of a composite compliant baffle

The response of a composite baffle, consisting of a compliant layer and a signal conditioning plate, to mechanical and acoustical excitations is calculated. Fluid loading is included in the calculation, and the coupling of the structure to the acoustic field is treated exactly. Comparison is made between the response of the compliant layer to a mechanical excitation, and another commonly used metric for baffle performance, viz., acoustic insertion loss. Calculations are carried out for a representative example.

Gas Turbine Silencers

The silencing of gas turbine installations is primarily a problem of attenuating the noise from the atmospheric inlet and the exhaust openings except where installations are made in residential or rural areas in which case the sound from the gas turbine enclosure, auxiliaries, and driven equipment must also be included as part of the silencing program. The subject matter of this paper is limited to the inlet and exhaust openings. The amounts of attenuation that can be obtained from natural factors such as divergence, directivity, air attenuation, and duct configuration are given and graphically shown. The sound absorbing qualities of baffles for the absorption of sound in the eight octave bands is described. At elevated temperatures, the performance of baffles at any octave band must be adjusted to the wavelength at the elevated temperature. Airflow characteristics are designed to be compatible with turbine operating efficiencies. Accepted fabrication practice is described and mechanical performance standards recommended. Properly designed silencers incorporate structurally adequate and durable casings, balanced sound attenuation, and pressure drops that will not adversely affect turbine performance.