Boundary Layer Impedance model to analyse the visco-thermal acousto-elastic interactions in centrifugal compressors. (August 2018)

• Record Type: Journal Article
• Authors: Jith, Jithin; Sarkar, Sunetra
• Is Part Of: Journal of fluids and structures. Volume 81(2018)
• Page Start: 179
• Page End: 200
• Publication Date: 2018-08
• Subjects: Acousto-elastic interaction -- Visco-thermal acoustics -- Centrifugal compressor -- Model order reduction; Fluid-structure interaction -- Periodicals; Fluid mechanics -- Periodicals; Structural dynamics -- Periodicals; Structural analysis (Engineering) -- Periodicals; 620.106
• DOI: 10.1016/j.jfluidstructs.2018.05.002
• Languages: English
• ISSNs: 0889-9746

Abstract

Abstract: Conventional acousto-elastic interaction studies on centrifugal compressors generally ignore the dissipative effects of visco-thermal phenomena present in all acoustic fluids. This work presents a numerically efficient framework for solving acousto-elastic problems, while taking visco-thermal effects into consideration, in centrifugal compressor-like geometries in the frequency domain. Compared to conventional acousto-elastic analyses, the framework enables the computation of a more realistic estimate of the frequency response of a centrifugal compressor. The acoustic fluid is modelled using Boundary Layer Impedance (BLI) model which accounts for dissipative visco-thermal effects through an impedance-like boundary condition. An improved finite element implementation is presented which reduces the computational time of the BLI acousto-elastic model to almost half, while not compromising on accuracy. To further reduce the computational cost, a Krylov subspace based reduced order model (ROM) is developed and implemented in the analysis. The ROM is specifically designed to handle frequency dependent system matrices encountered in the BLI acousto-elastic analysis. Highlights: A numerically efficient visco-thermal acousto-elastic framework is proposed. Fluid is modelled using a one-step (more efficient) Boundary Layer Impedance model. Model order reduction is performed using a frequency dependent rational Krylov method. Damping ratios are seen to decrease as pressure in the side-cavities increases.