Experimental methodology for turbocompressor in-duct noise evaluation based on beamforming wave decomposition

Torregrosa, A.J.; Broatch, A.; Margot, Xandra; García-Tíscar, J.

doi:10.1016/j.jsv.2016.04.035

Cited by 16 publications

(18 citation statements)

References 37 publications

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“…The methodology chosen for measuring sound intensity is based on pressure wave decomposition, so that the effect of mean flow velocity on sound propagation is accounted for. A detailed step-by-step explanation can be found in [23].…”

Section: Noisementioning

confidence: 99%

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Local flow measurements in a turbocharger compressor inlet

Torregrosa

Broatch

Margot

et al. 2017

Experimental Thermal and Fluid Science

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This paper describes an experimental study carried out with the objective of characterizing flow instabilities in turbocharger compressors, specially the distribution of the high-temperature compressed backflow that appears upstream of the impeller at marginal surge conditions. The inlet of a test compressor was fitted with linear and circumferential thermocouple arrays in order to measure the temperature distribution caused by this backflow, whose independence of duct wall temperature was validated through thermographic imaging. Miniaturized pressure probes at the inducer and diffuser showed how pressure spectra varied during the different operating conditions. Induct acoustic intensity was measured in both the inlet and the outlet to investigate the correlation between a known super-synchronous broadband issue known as whoosh noise and the backflow behaviour as characterized by local pressure and temperature. Analysis of the results points to inlet whoosh noise being boosted by this reversed flow but not caused by it, the source probably being located at or downstream of the compressor impeller.

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Section: Noisementioning

confidence: 99%

“…Following the interpolation procedure described in [23] it is possible to construct "noise charts" that allow for an easy visualization of the variation of the sound intensity level in a given frequency band with the operating condition of the compressor. These charts were calculated for the 1 -3 kHz band, and the result is shown in Fig.…”

Section: Noisementioning

confidence: 99%

Local flow measurements in a turbocharger compressor inlet

Torregrosa

Broatch

Margot

et al. 2017

Experimental Thermal and Fluid Science

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“…Internal (in-duct) pressure approach [6,14] is employed in this work to investigate the flow characteristics and compute the acoustic spectra of the compressor operating near surge. The methods like external radiated noise [4,5] and orifice noise [10] are not considered due to additional computational overhead required for solving the noise propagation and noise radiation [18]. The internal pressure fluctuations are numerically determined by solving unsteady Navier-Stokes equations for each control volume of the computational domain in their conservation form using a commercial CFD coupled solver, ANSYS CFX [19].…”

Section: Methodsmentioning

confidence: 99%

Acoustic and pressure characteristics of a ported shroud turbocompressor operating at near surge conditions

et al. 2019

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The operation of compressor at lower mass flow rates is limited by surge which is marked by large fluctuations in operational variables and accompanied by significant increase in noise. Ported shroud casing treatment is a widely used method to control the flow near unstable conditions in order to obtain a stable operation and enhance deep surge margin. The research on the acoustic effects of the ported shroud design is limited. Therefore, this paper numerically characterises the acoustic features of a turbocharger compressor with ported shroud design operating at marginal or soft surge conditions and investigates the correlation between acoustic characteristics and the spatial flow structures. The acoustic and the flow field features are analysed using spectral signatures obtained from an experimentally validated numerical model using both performance and acoustic measurements. Propagation of the frequency content through the ducts has been estimated with the aid of the beamforming and method of characteristics to enhance the content coming from the compressor. Expected acoustic phenomena such as rotating order tones and blade passing peaks are correctly identified in the modelled spectrum with the limitation to capture the specific broadband features. Hence, the numerical model can be used to further the research encompassing the impact these flow enhancement solutions have on the noise emission of the turbocharger. Inspection of the flow field shows radially exiting fluid at the ported shroud slot leading to the formation of the high-speed jets exiting the ported shroud cavity. Circumferential propagation of the stall cells is also identified in the impeller. Further inspection of the pressure field through modal decomposition implies the localisation of the energetic noise sources in the impeller downstream components. The influence of the ported shroud cavity on the acoustic characteristic of the compressor is not significant and is limited to the propagation of the tonal noise in the direction of impeller upstream.

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“…This short pipe included fast piezoelectric pressure transducers in order to accurately detect deep surge. However, no acoustic intensimetry could be performed as the pipes were too short for proper flow development [18,19].…”

Section: Anechoic Turbocharger Test Rig Setupmentioning

confidence: 99%

Impact of simple surge-enhancing inlet geometries on the acoustic behavior of a turbocompressor

Broatch

Margot

García-Tíscar

et al. 2018

International Journal of Engine Research

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This paper reports the results of an experimental campaign where four different inlet geometries for the compressor of an automotive turbocharger were acoustically characterized. These four geometries (a straight pipe for reference, a tapered duct, a 90º elbow and a reservoir) were selected for their potential for deep surge margin enhancement, while being simple enough to be commonly found in production vehicles. A detailed measurement of this surge margin enhancement was performed, together with acoustic measurements of both radiated and orifice noise at design conditions of best isentropic efficiency and also close to the deep surge limit. Results demonstrated that while all the proposed geometries indeed enlarged the usable air mass flow range, changes in the acoustic behaviour of the system could be positive, neutral, or even negative. It is therefore important to carefully consider accurate noise measurements before implementing these geometric solutions in production vehicles, and to further pursue research on the link between the characteristic flow pattern produced by each inlet geometry and the noise emission of the turbocompressor.

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Experimental methodology for turbocompressor in-duct noise evaluation based on beamforming wave decomposition

Cited by 16 publications

References 37 publications

Local flow measurements in a turbocharger compressor inlet

Local flow measurements in a turbocharger compressor inlet

Acoustic and pressure characteristics of a ported shroud turbocompressor operating at near surge conditions

Impact of simple surge-enhancing inlet geometries on the acoustic behavior of a turbocompressor

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