Grazing flow refers to the effect of flow at an angle on impedance, with a resistance proportional to the grazing flow Mach number. You might find these chapters and articles relevant to this topic.

Nov 5, 2023 · An established protocol for impedance eduction is based on a search procedure in which wall impedance in a duct propagation model is varied to obtain an acoustic field converging with one measured in a grazing flow duct.

an experimental investigation of the grazing flow impedance duct at the university of florida for acoustic liner applications by brandon l. bertolucci a dissertation presented to the graduate school of the university of florida in partial fulfillment of the requirements for the degree of doctor of philosophy university of florida 2012

Mar 1, 2025 · Explicit design guidelines for key components of a grazing flow test facility. High-quality flow and acoustic conditions realized by the facility. Systematic verification of the facility's effectiveness in liner impedance eduction.

However, grazing-flow duct facilities commonly employ ducts with a relatively small rectangular cross section in which the grazing flow possesses gradients in both transverse directions of the impedance tube.

Jan 1, 2023 · When there’s grazing flow in the duct, the exchange of sound incident direction mainly affects the acoustic characteristics of HR1.

Nov 11, 2012 · Single Mode Theory for Impedance Eduction in Large-Scale Ducts with Grazing Flow

Nov 4, 2012 · Impedance models for single and two degree of freedom linings and correlation with grazing flow duct testing

This report details experiments in the NASA Langley Grazing Flow Impedance Tube to quantify the relative drag of several perforate-over-honeycomb liner configurations at flow speeds of M=0.3 and 0.5.

The performance of a liner installed at the wall of a duct can be described by its acoustic impedance. Since the presence of an air flow inside the duct dramatically affects the liner behavior, it is essential to test the treatment under well …