Local flow measurements in a turbocharger compressor inlet

Margot

International Journal of Engine Research

et al. 2018

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.

Section: Operating At Design Conditionssupporting

confidence: 57%

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

Margot

International Journal of Engine Research

et al. 2018

Section: Ps Blocked Configurationmentioning

confidence: 73%

“…It is interesting to point out that the RO tones can still be observed in the inducer spectrum of PS blocked configuration operating at the design point which are not observed in the inducer spectrum of a similar compressor but without any casing treatment (Non-PS) investigated by Torregrosa et al [42]. The general trends of the spectra at the diffuser, inlet and outlet location for PS blocked configuration and Non-PS compressor Torregrosa et al [42] are reasonably similar. Furthermore, the broadband elevation observed in the diffuser spectra of both PS open and blocked compressor configuration operating at the design condition is also present in the diffuser spectra presented by Torregrosa et al [42].…”

Section: Ps Blocked Configurationmentioning

confidence: 73%

Acoustic characterisation of a small high-speed centrifugal compressor with casing treatment: An experimental study

Sharma

Aerospace Science and Technology

et al. 2019

Self Cite

With the advancements in manufacturing, materials and computational methods, turbomachinery designs have become more efficient providing higher specific power and reliability with lower weight and cost. The rotational speed of turbomachines has increased while the overall machine size has decreased for a similar power output leading to the pervasive presence of small, high-speed turbomachines, specifically centrifugal compressors in helicopters, unmanned aerial vehicles (UAVs), auxiliary power units (APUs), turbochargers and micro gas turbines. In addition to superior aerodynamic performance over a wide range, increased operating speeds have made the acoustic emissions of small centrifugal compressors a critical aspect of design. Therefore, this work presents an experimental campaign to characterise the acoustic behaviour of a compressor with an intent to quantify the dominant features of the flow-induced noise for design and near surge operating conditions. Furthermore, the campaign is extended to establish the impact of the ported shroud casing treatment and operating speed on the acoustic emission of the compressor. The induct noise measurement method is used in this work to quantify the noise generated in the compressor by measuring pressure fluctuations near the inducer and diffuser while the propagation of the generated noise to the ducts is computed from an array of piezoelectric sensors. Spectra at the design operating point are dominated by tonal noise while broadband noise content is the dominant feature of spectra for near surge operation. Although the ported shroud cavity does not significantly alter the overall noise levels of the compressor operating at design condition, it does seem to propagate tonal noise. For near surge operation, the casing treatment positively impacts the acoustic emission with a reduction of approximately 10 dB in the range up to the blade pass frequency. Furthermore, various broadband features are also observed to be alleviated by the casing treatment.

“…Furthermore, while uniform, unidirectional flow is assumed, it is known that between the onset of the marginal surge conditions to the deep surge limit, recirculating backflow at high temperature is present in the inlet section [23]. Also, while evanescent modes may not fully propagate beyond a short distance, both these local phenomena near the compressor may induce vibroacoustic excitation on the pipes, often made of rigid plastic materials to save weight and cost, and thus still radiate noise.…”

Section: Analytical Spinning Modesmentioning

confidence: 99%

Dynamic mode decomposition of the acoustic field in radial compressors

Aerospace Science and Technology

Roig

et al. 2019

Self Cite

Widely recognized since the beginning of air travel as a major issue, noise reduction remains nowadays a pressing concern for all stakeholders in the aviation industry. While aeroengine compressors, specially at the approach phase, have been historically identified as a leading source of noise, most of the research has been conducted on compressors of the axial type. However, radial compressors are found in a wide array of applications: smaller business jets, helicopters, unmanned aerial vehicles (UAVs), auxiliary power units (APUs), turbochargers for reciprocating engines, etc. Owing to their geometrical particularities, radial compressors feature flow patterns that differ from their axial counterparts, leading to different acoustic performance but also opening the door for different optimization approaches. Yet, classical modal decomposition techniques focused on duct propagation may fail to reveal the complex interactions between geometry and flow features that act as noise sources. In this paper we apply, in addition to the classical approach, a data-driven Dynamic Mode Decomposition (DMD) to pressure data coming from a Detached Eddy Simulation (DES), in which we have experimentally validated the correct reproduction of the modal behaviour of the compressor, thus obtaining in-depth details of the link between flow phenomena and noise generation and transmission across the inlet and outlet ducts.