A combined time and frequency domain approach for acoustic resonance prediction

Abstract

This is the accepted version of the paper.This version of the publication may differ from the final published version.Permanent repository link: http://openaccess.city.ac.uk/7905/ Link to published version: http://dx. AbstractA general time and frequency methodology has been developed to identify acoustic resonance conditions of internal flow configurations. The resonant frequencies and the corresponding acoustic modes are determined by imposing onto the flow a time-dependent excitation at several locations on the boundary. The resulting time-domain responses of the pressure signals, which are computed via an unsteady Favre-Reynolds averaged Navier-Stokes solver, are used to determine the frequency response function matrix of the fluid which can be considered to be a multipleinput multiple-output system. The main test case was selected to be a closed-end cylindrical duct for which the effect of different excitation techniques on the predicted resonant acoustic field is discussed in detail. The last test case deals with the acoustic characterization of a 2-D channel with symmetric bumps and an inlet flow velocity of 17 ms −1 . It is shown that the methodology was suitable for identifying both axial and transverse acoustic modes in a 10 Hz -3 kHz frequency range.

An innovative simulation method for the estimation of the nozzle pressure pulsation attenuation

“…In the case of variable speed compressors, this is not efficient since pressure pulsations have to be attenuated for a wide range of frequencies. This is the reason why other possibilities for pressure pulsations damping are highly desirable (Chassaing et al., 2008; Huang and Jiang, 2007).…”

“…In some cases, the results discrepancy of the conventional Helmholtz method may reach 90%, therefore a new transmittance matrix method was introduced and significant improvement was achieved (Cyklis, 2001). A modified Helmholtz method was applied by the authors: Chassaing et al. (2008); Georges et al.…”

“…In some cases, the results discrepancy of the conventional Helmholtz method may reach 90%, therefore a new transmittance matrix method was introduced and significant improvement was achieved (Cyklis, 2001). A modified Helmholtz method was applied by the authors: Chassaing et al (2008); Georges et al (2005) and Huang and Jiang (2007) this was to model and analyse different acoustic systems. Car mufflers, vibrations and pulsations are discussed in Andersen (2008) and Mehidizadeh and Paraschivois (2005).…”