Duct liner optimization for turbomachinery noise sources

Abstract

An acoustical field theory for axisymmetric multisectioned duct liners is combined with a numerical minimization algorithm to predict optimal one- and two-sectioned liner configurations producing maximum sound attenuation. Optimal inlet liner impedance properties calculated by this method are presented for a research compressor operating at about 0.4 Mach number. Kemp-Sears theory is used to describe the rotor/stator viscous wake interaction effects. Comparisons with data presented for point and plane-wave sources indicate that optimal liners for complex turbomachinery sources cannot be easily inferred from data based on these simpler source models.

Advanced Noise Control Fan Direct Aeroacoustics Predictions Using a Lattice-Boltzmann Method

“…The corresponding modal power P mnf is obtained from Eq. (10). As explained in the previous section, cut-off modes are disregarded from the modal decomposition.…”

“…In the past decade, an effort towards the development of efficient acoustics liner aiming to reduce mainly the tonal part of the noise has been carried out. Optimization algorithms, based on the modal decomposition of the sound pressure propagation, help improve and accelerate the design of such efficient liners 10,11 . A method allowing accurate modal decomposition as well as a good estimation of overall broadband content is therefore required.…”

A Requirements-Driven Optimization Method for Acoustic Treatment Design

“…(6) is the same as the bandwidth used in Eqs. (2) and (3). The model can represent complex suppression shapes with two peaks, perhaps imitating performance of a double degree-of-freedom perforate-over-honeycomb liner.…”

“…Historically, liner design variables were selected to maximize the attenuation of modes exiting a duct (e.g., [1,2]), optimized to ensure that certain spinning modes were cut off [3], or targeted simply at a particularly problematic fan interaction tone [4]. But, looking to the future, industrial innovations such as additive manufacturing are enabling new liners with multiple degrees of freedom.…”

A Requirements-Driven Optimization Method for Acoustic Liners using Analytic Derivatives

“…Historically, liner design variables were selected to maximize the attenuation of modes exiting a duct (e.g., [2,3]), optimized to ensure that certain spinning modes were cut off [4], or targeted simply at a particularly problematic fan interaction tone [5]. But looking to the future, industrial innovations such as additive manufacturing are enabling new liners with multiple degrees of freedom.…”