Radial turbine sound and noise characterisation with acoustic transfer matrices by means of fast one-dimensional models

Abstract

Estimating correctly the turbine acoustics can be valuable during the engine design stage; in fact, it can lead to a more optimised design of the silencer and aftertreatment, as well as to better prediction of the scavenging effects. However, obtaining the sound and noise emissions of radial turbocharger turbines with low computational costs can be challenging. To consider these effects in a time-efficient manner, the acoustic response of single-entry radial turbines can be characterised by means of acoustic transfer matrices that change with the operating conditions. Exploiting the different time-scales of the acoustic phenomena and the change in the operating point of the turbine, lookup tables of acoustic transfer matrices can be computed. Then, the obtained characterisation can be used in mean-value engine models. This article presents a method for generating these lookup tables by means of fast one-dimensional simulations of thoroughly validated fidelity, in terms of both acoustics and extrapolation capabilities. Due to the inherent behaviour of radial turbines, the number of computations needed to fill the lookup tables is relatively small, so the method can be used as a simple preprocessing phase before mean-value simulation campaigns.

Twin-entry turbine losses: An analysis using CFD data

“…Very different phenomena can be simulated, as heat transfer models, 5 turbocharger unsteady behaviour prediction, 6 internal details of fuel injectors, 7 URANS/LES cylinder simulations 8,9 or noise characterisation. 10,11 One of the most wide and efficient techniques for reducing the emissions is turbocharging the ICE. 12 The engine exhaust turbine configuration most used until relatively recently was the single volute turbine.…”

“…Very different phenomena can be simulated, as heat transfer models, 5 turbocharger unsteady behaviour prediction, 6 internal details of fuel injectors, 7 URANS/LES cylinder simulations 8,9 or noise characterisation. 10,11…”

A numerical study for correlating performance versus number of blades and investigating flow characteristics and loss generation of an automotive radial flow turbine

“…Bahiuddin et al 11 developed a bond graph model of a VGT turbine with a passive actuator. Torregrosa et al 12 modeled turbocharger turbines as a two-ports acoustic model with a map extrapolation procedure by means of an acoustic matrix lookup. They showed a noticeable time-scale separation between the evolution of the engine exhaust pressure and temperature pulses and the turbine characteristics (i.e.…”

Evolution of flow characteristics in a centrifugal compressor with an increase in operating speed

“…The numerical investigations by Christou, 5 Semlitsch et al 4 and Yang et al 6 explored flow characteristics of the compressor over various mass flow states while the impact of PS and operating speed on the acoustic emission was not considered. Zheng et al 7,8 and Torregrosa et al 9,10 experimentally investigated the flow instabilities and acoustic characteristics of the compressors without casing treatment. Furthermore, the impact of operating speed was not investigated.…”