https://doi.org/10.1140/epjp/s13360-026-07323-2
Regular Article
Numerical and experimental analysis of flow–acoustic interaction in a hybrid muffler incorporating half-elliptical baffles
1
Department of Mechanical Engineering, Vishwakarma Institute of Technology, 411037, Pune, Maharashtra, India
2
Department of Mechanical Engineering, D Y Patil College of Engineering Akurdi, 411044, Pune, Maharashtra, India
3
Department of Mechanical Engineering, S.N.D. College of Engineering & Research Center, 423401, Babhulgaon Kh., Yeola, Maharashtra, India
4
Department of Mechanical Engineering, Pune Vidyarthi Griha’s College of Engineering & S. S. Dhamankar Institute of Management, 422004, Nashik, Maharashtra, India
5
Department of Automation and Robotics Engineering, MES’s Wadia College of Engineering, Pune-01, India
6
Industrial Tribology Laboratory, Department of Mechanical Engineering, M.E.S. Wadia College of Engineering, S.P. University, 411001, Pune, India
7
Department of Mechanical Engineering, AISSMS College of Engineering, 411001, Shivajinagar, Pune, Maharashtra, India
a
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b
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Received:
14
November
2025
Accepted:
13
January
2026
Published online:
29
January
2026
Abstract
This work examines the coupled flow–acoustic behaviour of a compact hybrid motorcycle muffler incorporating half-elliptical baffles, dual Helmholtz resonators, and ceramic-wool absorptive packing for a high-speed single-cylinder engine. Baseline spectral analysis of the untreated exhaust identified a dominant tonal component at 511 Hz, which guided the temperature-corrected tuning of the resonator cavities. One-dimensional acoustic simulations using Ricardo Wave predicted frequency-dependent transmission loss characterized by resonator-induced attenuation in the mid-frequency range and a progressive broadband increase associated with dissipative mechanisms. Three-dimensional CFD analysis revealed that the half-elliptical baffles condition the internal flow by redirecting the exhaust stream towards the absorptive region while limiting large-scale recirculation, thereby promoting stable acoustic coupling with the resonators under varying operating conditions. Experimental validation was carried out using ISO 5130:2019–compliant, dB(C)-weighted sound pressure level measurements, which indicated reductions of approximately 10–11 dB(C) at idle and 14–15 dB (C) at 7500 rpm, achieving compliance with Formula Bharat noise limits. The combined numerical and experimental results indicate that curvature-conditioned flow management, when integrated with reactive and dissipative elements, provides an effective and compact approach for broadband and tonal noise reduction in small-displacement engine exhaust systems.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2026
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
