Numerical investigation of error mechanisms in near‐field acoustic holography (NAH)

On nearfield acoustic holography

Such functions u are called radiating solutions. Pressure measurements are taken by acoustical sensors located in a domain Ω0 inside or outside the cabin or on a surface Γ0 = ∂Ω0 . Our goal is to reconstruct u inside Ω, or the normal velocity v = ∂νu on Γ = ∂Ω, (ν is the unit exterior normal to ∂Ω). This is a mathematical model of the nearfield acoustic holography [W], [Wu]. H(m)(Ω) denotes the...

Development of an Energy-Based Nearfield Acoustic Holography Technique

Acoustical-based imaging techniques have found merit in determining the behavior of vibrating structures. These techniques are commonly used in numerous applications to obtain detailed noise source information and energy distributions on source surfaces. This work focuses on the continued development of the nearfield acoustical holography (NAH) approach. Source reconstructions using NAH are rel...

Session 1pSPa: Nearfield Acoustical Holography (NAH) Measurements and Applications 1pSPa4. Modified statistically optimized near-field acoustical holography for jet noise characterization

Near-field acoustical holography has been shown to be a useful tool for visualizing jet noise fields. It has been applied to a full-scale jet on an installed military aircraft with promising results, but the source characteristics in the extreme near field have been difficult to characterize because of the interference of acoustic reflections off the rigid reflecting plane beneath the jet. To p...

Numerical investigation of acoustic solitons

Real-time Nearfield Acoustic Holography: Implementation of the Direct and Inverse Impulse Responses in the Time-wavenumber Domain

The aim of the study is to demonstrate that some methods are more relevant for implementing the Real-Time Nearfield Acoustic Holography than others. First by focusing on the forward propagation problem, different approaches are compared to build the impulse response to be used. One of them in particular is computed by an inverse Fourier transform applied to the theoretical transfer function for...