Publisher's Synopsis
The primary purpose of this study is to develop improved models for the acoustic impedance of treatment panels at high frequencies, for application to subscale treatment designs. Effects that cause significant deviation of the impedance from simple geometric scaling are examined in detail, an improved high-frequency impedance model is developed, and the improved model is correlated with high-frequency impedance measurements. Only single-degree-of-freedom honeycomb sandwich resonator panels with either perforated sheet or "linear" wiremesh faceplates are considered. The objective is to understand those effects that cause the simple single-degree-of- freedom resonator panels to deviate at the higher-scaled frequency from the impedance that would be obtained at the corresponding full-scale frequency. This will allow the subscale panel to be designed to achieve a specified impedance spectrum over at least a limited range of frequencies. An advanced impedance prediction model has been developed that accounts for some of the known effects at high frequency that have previously been ignored as a small source of error for full-scale frequency ranges.Kraft, R. E. and Yu, J. and Kwan, H. W.Langley Research CenterACOUSTIC IMPEDANCE; HIGH FREQUENCIES; AIRCRAFT MODELS; SCALE MODELS; AIRCRAFT NOISE; NOISE PREDICTION (AIRCRAFT); AEROACOUSTICS; HONEYCOMB STRUCTURES; PANELS; SANDWICH STRUCTURES; FAN BLADES
