Browse Topic: Mufflers

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Design, Manufacturability, Optimization, and Validation of a Reactive-Style Muffler for a Formula SAE Race Car2025-01-002405/05/2023
The noise generated by internal combustion engines, particularly in high-performance vehicles like Formula SAE race cars, presents a significant challenge in adhering to strict competition noise regulations. To address this issue, mufflers are essential for reducing acoustic emissions. This study focuses on the design, manufacturability, optimization, and validation of a reactive-style muffler specifically for a Formula SAE combustion competition car. The proposed muffler utilizes two chambers to generate destructive interference, targeting the two dominant exhaust frequencies of the Honda CBR600RR engine to maximize transmission loss and reduce noise levels below the SAE-mandated range of 103–110 dB(C). A 3D model of the muffler was developed using SolidWorks, capturing the precise geometries required for acoustic optimization. The exhaust noise and muffler performance were simulated using GT-Suite, allowing for an evaluation of noise attenuation across engine speeds. Experimental
Labao, Kai, Middleton, Nicholas, Nuszkowski, John
Technical Paper
Investigation on the Effect of Design feature on Acoustic Performance of Exhaust Muffler for Vehicle2022-28-048811/18/2022
Primarily, Acoustic performance of muffler are evaluated by insertion loss (IL) and backpressure/restriction. Where Insertion loss is mainly depends upon proper selection of muffler volume, which is proportional to Engine Swept volume, along with internal design configuration, which drives the acoustic principle. Same time, meeting the vehicle level pass by noise (PBN) value as per regulatory norms and system level backpressure as per engine specification sheet are the key evaluating criteria of any good exhaust system. Here, a new Reactive/Reflective type muffler of tiny size have designed for heavy commercial vehicle application, which is unique in shape and innovative to meet desire performance. In this design, mainly sudden expansion, sudden contraction, flow through perforation and bell-mouth flow phenomenon are used. The performance of this tiny muffler are optimized using multilevel design of experiments (DoE) by the measurement of pass by noise (PBN) and near exhaust noise (NEN
Biswas, Sanjoy, Merchant, Preetam, Ghate, Asmita
Technical Paper
DESIGN AND ANALYSIS OF A MUFFLER FOR ENGINE EXHAUST NOISE AND HEAT REDUCTION2021-28-012809/15/2021
Exhaust noise and heat from engines is one of component noise pollution to the environment. Exhaust systems are developed to attenuate noise meeting required db levels and sound quality, emissions based on environment norms. Mufflers are important part of engine system and commonly used in exhaust system to minimize sound transmissions caused by exhaust gases and reduction of heat. Attaching a muffler in the exhaust pipe is the most effective means of reducing noise and heat. The aim of our project is to design and analyse a muffler for engine exhaust noise reduction. The suitable design and development will help to reduce the noise level and heat level, but at the same time the performance of the engine should not be hampered by the backpressure caused by the muffler. In this analysis 3D models are constructed using Solid Works software before exporting to ANSYS FLUENT CFD software for analysis. At ANSYS/FLUENT, pressure conditions will be specified as the inlet and outlet boundary
Deepan Kumar, Sadhasivam, Praveenkumar, Nagarajan, S, Arulkumar, N, Boopalan, PRAVEENKUMAR, S
Technical Paper
Determination of Transmission and Insertion Loss for the General Multi-Inlet Multi-Outlet Case2016-01-131004/05/2016
Prior research on assessing multiple inlet and outlet mufflers is limited, and only recently have researchers begun to consider suitable metrics for multiple inlet and outlet mufflers. In this paper, transmission loss and insertion loss are defined for multiple inlet and outlet mufflers using a superposition method that can be extended to any m-inlet n-outlet muffler. Transmission loss is determined assuming that the sources and terminations are anechoic. On the other hand, insertion loss considers reflections. For both metrics, the amplitude and phase relationship between the sources should be known a priori. This paper explains both metrics, and measurement of transmission and insertion loss are demonstrated for a 2-inlet 2-outlet muffler with good agreement.
Zhang, Yitian, Herrin, David W., Wu, T., Hua, Xin
Journal Article
Numerical Determination of Transfer Impedance for Perforates2015-01-231206/15/2015
A simplified method to model perforated tubes in mufflers is the equivalent transfer impedance approach. Various empirical formulas that consider the porosity, hole diameter, wall thickness, and flow type have been proposed to date. They normally work very well under the conditions that the formulas are intended for. However, there are situations that the empirical formulas may not be able to cover. In this paper, we propose a simple BEM-based numerical procedure to determine the transfer impedance from a small perforate sample, and then send the transfer impedance to the muffler BEM model for analysis purposes. Numerical results are verified in three test cases.
Wang, P., Li, J., Wu, T. W.
Journal Article
Pressure Drop Characteristics of Perforated Pipes with Particular Application to the Concentric Tube Resonator2015-01-230906/15/2015
The bias flow in Concentric Tube Resonator (CTR) is a flow-induced phenomenon in which the pressure gradient along the radial direction is produced by the kinetic energy of the flow. As a result, the flow dynamics in CTR is characterized by bias flow into the annular cavity in the upstream and outflow from the annular cavity in the downstream of the flow. This is due to the change in direction of the radial component of the bias flow at a point called the point of recovery, as a consequence of mass conservation. The pressure drop of CTR is a complex function of the momentum flux and other geometric parameters such as porosity, open area ratio, discharge coefficient of the perforated holes, bias inflow, bias outflow, grazing flow and length. In this study, numerical experiments are conducted to obtain an empirical formula for the friction factor of perforated pipes which are extensively used in automotive mufflers. The finite element based numerical results are validated with test
Neihguk, David, Munjal, M.L., Prasad, Abhinav
Technical Paper
Modular Exhaust Design and Manufacturing Techniques for Build-to-Order Muffler SystemsTBMG-2221506/01/2015
Managing the acoustic signature of military vehicles can play a critical role in the safety of soldiers. Low-frequency sounds propagate through the atmosphere, resulting in unacceptable acoustic vehicle detection ranges, requiring relatively large silencer structures to mitigate. Currently, these requirements are met by using a custom muffler that is hand-assembled using low-volume prototyping manufacturing techniques. This method results in significant engineering and manufacturing time.
Magazine Article
Application of the Fourier Amplitude Sensitivity Test (FAST) to Analyze Thermal Performance of Vehicle Underbody Components2015-01-043804/14/2015
This paper describes the application of the Fourier Amplitude Sensitivity Test (FAST) method [1] to investigate the effect of uncertainty in design parameters on the thermal system performance of vehicle underbody components. The results from this study will pinpoint the design parameters which offer the greatest opportunity for improvement of thermal system performance and reliability. In turn, this method can save engineering time and resources. An analytical model was developed for a vehicle underbody system consisting of a muffler, heat shield, and spare tire tub. The output from this model was defined as the temperature of the spare tire tub. The majority of the input parameters in this model deviate from their nominal values due to environmental factors, wear and ageing, and/or variation in the manufacturing process. Using MATLAB software package, the model was simulated with input parameters which were simultaneously and sinusoidally varied at distinct frequencies over their
Lehman, Ashley, Stoilov, Vesselin, Sobiesiak, Andrzej
Journal Article
Using the Reciprocal Work Identity to Evaluate the Transmission Loss of Mufflers2013-01-188805/13/2013
Transmission loss (TL) is a good performance measure of mufflers since it represents the muffler's inherent capability of sound attenuation. There are several existing numerical methods, which have been widely used to calculate the TL from numerical simulation results, such as the four-pole and three-point methods. In this paper, a new approach is proposed to evaluate the transmission loss based on the reciprocal work identity. The proposed method does not assume plane wave propagation in the inlet and outlet ducts, and more importantly, does not explicitly apply the anechoic termination impedance at the outlet. As a result, it has the potential of extending TL computation above the plane wave cut-off frequency.
Zhou, L., Herrin, D. W., Wu, T. W.
Journal Article
Adding Bypass Ducts to Enhance Muffler Performance without Increasing Size2013-01-188205/13/2013
It was demonstrated that a bypass duct similar to a Herschel- Quincke tube could be used to increase the transmission loss of mufflers at selected frequencies. In many cases, the duct can be short and thought of as a leak. It was shown that the optimal length and cross-sectional area could be determined by using a simple optimization technique known as the Vincent Circle. Most importantly, it was demonstrated that the attenuation at low frequencies could be improved by as much as 15 dB. To prove the concept, a muffler was designed and optimized using transfer matrix theory. Then, the optimized muffler was constructed and the transmission loss measured using the two-load method. The measured results compared well with prediction from transfer matrix theory. Boundary element simulation was then used to further study the attenuation mechanism.
Zhang, Y., Herrin, D. W., Wu, T. W.
Journal Article
Accurate Measurement of Small Absorption Coefficients2007-01-222405/15/2007
In this paper procedures for estimating the sound absorption coefficient when the specimen has inherently low absorption are discussed. Examples of this include the measurement of the absorption coefficient of pavements, closed cell foams and other barrier materials whose absorption coefficient is nevertheless required, and the measurement of sound absorption of muffler components such as perforates. The focus of the paper is on (1) obtaining an accurate phase correction and (2) proper correction for tube attenuation when using impedance tube methods. For the latter it is shown that the equations for tube attenuation correction in the standards underestimate the actual tube attenuation, leading to an overestimate of the measured absorption coefficient. This error could be critical, for example, when one is attempting to qualify a facility for the measurement of pass-by noise. In this paper we propose a remedy - to measure the actual tube attenuation and to use this value, as opposed to
Han, J., Herrin, D. W., Seybert, A. F.
Technical Paper
Investigations on Whistle Noise in Automotive Exhaust System Mufflers2005-01-236105/16/2005
Automotive exhaust mufflers are not only attenuating noise, but can, in fact, along with other exhaust components, generate noise within the exhaust system. This type of noise is commonly called “flow generated noise” to distinguish it from the “pulsation noise” excited by the combustion engine. Flow generated noise is normally very broad band but it can also have tonal regions. This tonal flow noise can sound like a whistle. In this contribution an experimental study of the generation and prevention of such whistle tones will be presented. The study was focused on perforated pipes in mufflers with different perforation patterns, hole sizes and hole shapes. The noise spectra have been measured on a flow bench at room temperature as well as under real (hot) conditions on a vehicle. The results will be correlated in terms of frequency and Strouhal number. Concepts to avoid or suppress these tones will also be discussed.
Jebasinski, Rolf, Leng, Sascha, Jess, Marco, Rose, Thomas
Technical Paper
An Optimization Tool for Exhaust System Design With Respect to Tail Pipe Noise Reduction2003-01-164605/05/2003
Faurecia has developed a numerical tool which allows an automatic optimization of an exhaust line with respect to tailpipe harmonic noise. An optimizer pilots an in-house acoustic software in order to find the exhaust line configuration which fulfills the targets on the two first harmonics. The optimization method as well as the acoustic prediction tool are presented in this paper. Then, two examples of application of the methodology are detailed.
Boudoy, Marianne, Jaskulski, Jean-Yves
Technical Paper
Medium- and Heavy-Duty Truck Converter/Muffler ConfigurationJ1642_200111 (Current)11/15/2001
This SAE Draft Technical Report is intended to document the technical consensus of the current design state of converter/mufflers for heavy-duty emission classification diesel vehicle applications. This will maximize standardization and promote interchangeability of parts from different manufacturers. The purpose of this SAE Draft Technical Report is to give the technical community the opportunity to review, comment on, and use the Draft Technical Report prior to its final approval by SAE.
SAE IC Powertrain Steering Committee
Technical Standard
The numerical analysis and technique development on light truck muffler bracket forming2000-05-021906/12/2000
The light truck muffler bracket is a kind of deep and complicated stamping part which has curve flange. It is formed by once drawing with 3 mm thick 08TIL sheet. Since it is difficult to design good technique for the workpiece, after the muffler bracket was put into production, problems such as cracks at the bottom projecting corner and wrinkles at the curved flange corner often occurred. This led to high waste product ratio of 15 (and high substandard product ratio of 30). Therefore the part quality was heavily influenced, the production cost kept at high state for long term. In this paper, the geometry model of forming process part is built with the software Euclid3, the forming process of muffler bracket is numerically analyzed with the software LS-DYNA3D. The metal flow law and deformation character under the curve blankholding surface is revealed, in the meantime, the main reason of cracks and wrinkles appearing in the part during the forming process is studied, the direct reason
Xu, Cheng Lin, Zhu, Wei Cheng
Technical Paper
Correlation of Simulated and Measured Noise Emissions and Unsteady Gas Dynamic Flow from Engine Ducting96180608/01/1996
One-dimensional (1-D) unsteady gas dynamic models of a number of common muffler (or silencer) elements have been incorporated into a1-D simulation code to predict the impact of the muffler on the gas dynamics within the overall system and the radiated Sound Pressure Level (SPL) noise spectrum in free-space. Correlation with measured data has been achieved using a Single-Pulse rig for detailed unsteady gas dynamic analysis and a Rotary-Valve rig in conjunction with an anechoic chamber for noise spectra analysis. The results obtained show good agreement both gas dynamically and acoustically. The incorporation of these models into a full 1-D engine simulation code should facilitate the rapid assessment of various muffler designs prior to prototype manufacture and testing.
Mackey, D. O., Blair, G. P., Fleck, R.
Technical Paper
Acoustic Three Dimensional Finite Element Analysis of a Muffler96018902/01/1996
Three dimensional finite element analysis of mufflers has been carried out using ANSYS general purpose program. Analysis of simple expansion chamber muffler, extended tube muffler, tapered chamber muffler, offset chamber muffler and flow reversing chamber muffler has been carried out to predict the transmission loss. This three dimensional FEA technique has proved to be successful for the analysis of geometrically complicated mufflers where one dimensional theories can not be used. Parametric analysis of a simple expansion chamber muffler has been carried out to study the effect of expansion ratio, expansion chamber length, number of partitions within a chamber and unequal partitions. Analysis of acoustic cavity of a simple expansion chamber muffler has also been carried out to predict the natural frequencies and acoustic mode shapes.
Patil, Avinash R., Sajanpawar, P. R.
Technical Paper
Collector/Catalyst/Muffler Package: Racing Car Exhaust Noise Reduction95106002/01/1995
Significant reduction in the exhaust noise levels of racing cars has been achieved through the use of a special header-collector design. This design combines the primary header tubes, the collector, and the muffler into a compact package. The accommodation of exhaust systems on race cars -- especially those with mid or rear engine designs -- upsets the weight bias of the vehicle by moving the mass of the exhaust behind the rear axle, thus increasing the polar moment. The ducting of the exhaust to the rear also exposes vital components to extreme heat generated by the exhaust system. The CCM occupies fractionally more space than the header alone, allowing great flexibility in the design of the rest of the exhaust system. Testing has demonstrated that this design not only attenuates noise, but it provides increased horsepower and torque as well.
Borla, Alexander, Guzek, Joseph
Technical Paper
Medium- and Heavy-Duty Truck Converter/Muffler ConfigurationJ1642_199302 (Historical)02/19/1993
This SAE Draft Technical Report is intended to document the technical consensus of the current design state of converter/mufflers for heavy-duty emission classification diesel vehicle applications. This will maximize standardization and promote interchangeability of parts from different manufacturers. The purpose of this SAE Draft Technical Report is to give the technical community the opportunity to review, comment on, and use the Draft Technical Report prior to its final approval by SAE.
SAE IC Powertrain Steering Committee
Information Report
Rev-74-The University of Cincinnati ATV with Independent Suspension75014302/01/1975
The history and structure of the Recreational Ecological Vehicle Design Competition, REV-74, is discussed. In this competition, held at Houghton, Mich., several universities designed and constructed all-terrain vehicles which were evaluated in a series of test events. The University of Cincinnati's six-wheeled all-terrain vehicle is described in detail. Features included in the discussion are the vehicle's twin hydrostatic drive transmission, independent suspension, high-frequency muffler, and jet pump drive for water propulsion.
Morse, Ivan E., Shapton, William R.
Technical Paper
Control of Diesel Engine Exhaust Noise70070102/01/1970
The contribution of exhaust noise to total vehicle noise is identified by isolation and near field techniques. Control of exhaust noise by using the principles of absorptive, reactive, and dispersive mufflers and their combinations is examined. Guidelines are presented to help the engine designer in the selection of mufflers within the design limitations of size, weight, and engine performance loss.
Wu, Tang
Technical Paper
MUFFLER LOCATION IS IMPORTANT59009401/01/1959
DANNER, T. A.
Technical Paper
DEVELOPMENT ENGINEERING AND APPLICATION TO MUFFLER MANUFACTURE FOR HEAVY-DUTY ENGINES54018201/01/1954
BILLEY, LEINO H.
Technical Paper
COMMERCIAL VEHICLE EXHAUST NOISE - ITS CAUSE AND CURE “Problems of Truck Operator”53018401/01/1953
Technical Paper
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