Sound is attenuated by reflection and cancellation of sound waves compressor discharge details 40 mm types of mufflers 4 me 510 vibroacoustic design university of kentucky 3. The automotive muffler has to be able to allow the passage of exhaust gasses whilst restricting the transmission of sound. Design of the muffler will be generated according to requirements. Testing concludes that the exhaust system meets fsae regulations of 110 db at max engine speed and 100 db at idle. Example of calculation of back pressure and velocity in our example we have used a cat 3516 engine that has the following characteristics. Further simulation still needs to be conducted on the rest of the model. Development of methodology for simulation driven design.
P, india 2professor of dept of mechanical engineering, g. Bellows are typically used for exhaust systems with a diameter of 200 mm 8 in and larger. Goilkar3 1,2 me machine design student, 3principal, 1,2department of mechanical engineering, finolex academy of management and technology, ratnagiri, maharashtra, india 3finolex academy of management and technology, ratnagiri, india. Munjal 5 discussed about muffler analysis and design methods. From design calculations velocity of 50 ms is deduced and applied as a boundary condition to the inlet of the exhaust system.
Calculation of air volume to exhaust correction factors according to the type of installation chart 2 type of installation multiplication factor wallmounted hood 1. It describes the impact of the noise muffler on the pneumatic systems fast acting. There is a wealth of information available concerning air volume determination heating and cooling loads, fan selection and specification. Exhaust and muffler design of a formula sae car scribd. Engineering 3 me 510 vibroacoustic design university of kentucky 2. Types of mufflers university of kentucky college of. For those who want to get deeper into header design there is an inexpensive headerpipedesign program available on the internet called pipe max. The following silencers design flow must not exceed 9000 fpm.
May 06, 2017 heres what the inside of a muffler looks like and how it works. A flexible exhaust connection has three primary functions. Now after designing the target muffler, modified design of the muffler is designed using catia v5 and it is also saved with. Mastering exhaust system math to build highperformance engines. Target hydraulics make a list here for you learn and check when you design your hydraulic system hydraulic power pack unit or hydraulic components. Page objectoftheinvestigation 1 theory 3 calculationofmuffleralonglines followedinpreceedingtheory 11 thetests 15 descriptionofapparatus 16 descriptionofliufilerstested 19 datasheet 20 calculationofresults 21 resultsandconclusions 22 curves 25 figures 30. The cars system will be designed to utilize a sound absorption straight through type muffler rather than a sound canceling baffled muffler for the. Generally i find that changing the tuned length,intentionally or by mistake alters the power peak by about 500 rpms per inch,an inch shorter raises power peak 500 rpm and vice versa. An improved method for the design of expansion chamber mufflers. After benchmarking exercise, one needs to calculate the target frequencies to. For the love of physics walter lewin may 16, 2011 duration. Reactive silencer design is based either on the principle of a helmholtz resonator or an expansion chamber, and requires the use of acoustic transmission line theory. It is important to be accurate because one mistake can alter your other calculations and make them off.
An extensive literature is available on compressor muffler analysis and design 24. Design of mufflers and silencers university of kentucky college of. From the outside looking in, a tube wrapped around another tube with some packing isnt the way the technology is anymore. Objectives framing and benchmarking to obtain system inputs usually engine. Heres what the inside of a muffler looks like and how it works.
P, india abstract the present work aims at improve the frequency of nsd nash shell damper muffler by. The muffler manufacturers are doing all the math for us no need to reinvent the wheel. Pdf exhaust noise from engines is one of component noise pollution to the. Also this approach will predict design quality at earlier stage of muffler design. Modified mufflers internal structure is shown below in the figure with different views figure 3. Here, we take l 350 mm after studying various muffler lengths of similar engine mufflers and overall space available on a motorcycle for mounting of a muffler and hence. Experimental curves of attenuation plotted against frequency are presented for 77 different mufflers with a reflectionfree tailpipe. General design principles for an automotive muffler australian.
Calculation and design of exhaust noise mufflers for power engineering equipment igolkin a. Most of the literature about onedimensional transfer matrix approach to calculate muffler transmission loss tl is based on planewave. Target hydraulics assumes no liability for errors in data nor in safe andor satisfactory operation of equipment designed from this information. Back pressure 27 in h2o exhaust temp 945f exhaust mass flow 25480 lbshr exhaust outlet diameter 8 2 ports. The study depicts the common causes of silencer failures.
The model takes into account the installation of a noise muffler. A muffler have been designed, which is of supercritical grade type of making the muffler calculations have to. A performance exhaust system is a characterizing element for any internal combustion conveyance. Calculation and design of exhaust noise mufflers for power. Depending on which concept you use in muffler design, it is going to have a great impact on the tone that the muffler is going to have. Most formulas that are used to predict the transmission loss. The scope of our work is to establish a design methodology to make design process simpler and less time consuming by making use of acoustic theories 10, 11 and experience, in short practical approach to get better design. It achieves its supercritical status primarily from its length, as much as 16x pipe diameter. The muffling effect of helmholtz resonator attachments to. Some manufacturers include an absorptive section to reduce high frequency sound transmission, but that is not the case for the silencer design shown in the next slide. The supercritical grade muffler generally represents the top of the line for reactive mufflers. Weve got an easytoread exhaust system size table that is good for quick calculations. Experimental curves of attenuation plotted against frequency are presented for 77 different mufflers with a reflectionfree.
Dynamic modal analyses were carried out to determine. Design of mufflers and silencers noise and vibration short course dept. Exhaust optimization for viking motorsports formula sae team. Mar 10, 2015 this design generally attacks the higher frequencies. Investigation and optimization of the acoustic performance of. General design principles for an automotive muffler potente, daniel day design pty ltd, acoustical consultants, sydney, nsw au abstract this paper discusses the general principles of muffler design and explains the main advantages of various styles of mufflers. Tuning an exhaust system to a given application is a casebycase basis challenge. Calculation methods for predicting attenuation of parallel. The numerical model can further be used to optimize mufflerdesign, for extreme sound cancellation and high engine performance in automobiles. Pdf basic design methodology for muffler design, development. Billy boat summed up the muffler design process by saying, muffler design is fairly complex. As per the standards of the supercritical grade of mufflers, the diameter of the body should be about three times than the exhaust pipe diameter. They carried out exhaust muffler tests with an identical engine on a loaded test cell without the propeller and were able to claim a db noise reduction due to an exhaust muffler by using their best design.
They gave us some insight on how exhaust sizing and design can affect performance. Acoustics and flow field analysis of perforated muffler design mr. This type of design allows for a change in the noise frequency to a higher band, the results are a much simpler sound to attenuate this is accomplished by the annulling of the noise by a series of chamber with acoustical packing the multichambered design also allows us to attenuate the lower frequency bands present in the exhaust. This paper discusses the general principles of muffler design and explains the main advantages of. A muffler is used near the end of the exhaust system on a vehicle to reduce the noise emitted by the engine. Muffler design for a refrigerator compressor vamshidhar done general electric global research center, bangalore. Duct system design guide first edition 2003 mcgill airflow corporation mcgill airflow corporation one mission park groveport, ohio 43125 duct system design. University of maine fsae engine team mick peterson. Experimental investigation of muffler with comments on engine exhaust muffler design 3 j. Vcs, vcsa, vrs, sfh, cfh, rfh and rectangle type silencers lprs harco manufacturing co. Volume can be adjusted depending on the space constraint. Now, you have to calculate the sulphur dioxide so2 percentage in flue gas. Madhava reddy 1pg student of dept of mechanical engineering, g. Exhaust optimization for viking motorsports formula sae.
Flue gas steel stack design calculations learn chimney. Emphasis will be put in attempting to find more recent research and theories. Hydraulic calculationshydraulic system design calculations. Toyama 1958 aeronautical research institute, university of tokyo, report no. Dynamic modal analyses were carried out to determine the mode shapes, stresses and.
A concept in which simulations and calculations are used to aid the designer from the beginning of a design process. Exhaust stack silencer design using finite element analysis. Mastering exhaust system math to build highperformance. This drawing shows a 3 chamber critical grade muffler.
The transmission loss of single expansion chamber is 6. This is typically given as sound pressure level at 1 meter or similar distance. Engineering 7 university of kentucky 24 12 12 source 2 65040302010 0 10 20 0 200 400 600 800 frequency hz tl and il db insertion loss transmission loss pipe resonances inlet pipe outlet pipe expansion chamber muffler example tl and il. Muffler design, development and validation methods ijirset. That is why chambered mufflers have a low frequency sounds these sounds tend to be less annoying than the higher frequency sounds. Flexible connections should be installed as close as possible to the engine exhaust outlet. There have been significant changes in the design of muffler, also different theories we developed to understand various parameters like mass flow rate, volumetric flow rate, transmission losses, insertion losses, pressure drop, back pressure effects, calculate the chamber lengths. Pdf design and analysis of an automobile exhaust muffler. Exhaust and muffler design of a formula sae car free download as powerpoint presentation. This paper postulates the first stage in the design of an exhaust system, with the specified properties of the different material, the exhaust system is modeled by. Here we can see that in area a the sound wave reflects off the chamber wall and inverts in an attempt to cancel with the incoming sound waves.
While doing the flue gas steel stack design calculations you should consider the design formulas and local pollution control norms. Find out the percentage of sulphur content in the diesel you are using. When similar mufflers were tested on an aircraft engine, the exhaustnoise reduction fell short of that predicted from the transmission loss calculations ref. Pdf a practical approach towards muffler design, development. To ensure the impedance characteristics of helmholtz resonator, in additional to the noise energy dissipation of air, and to prevent the loss of purpose this study. Internal configuration of muffler and concept design diameter of muffler calculated as v m. The lower frequencies with longer wavelengths are less affected. Following are the broad steps followed to arrive at a good design of muffler making use of practical experimental data figure 1. Design and analysis of exhaust system for the two wheeler.
Muffler design by noise transmission loss maximization. The main focus of muffler design is to meet the maximum sound requirements while maintaining engine performance and efficiency. Muffler volume calculation based on the available data and theory of acoustics. The design of the steel stack or chimney is important from the diesel genset performance as well as air pollution point of view. Mar 30, 2015 for the love of physics walter lewin may 16, 2011 duration.
The header design was semifinalized and a computer animated model was created and a cfd simulation conducted for the exhaust primary pipes. Design data on pressure drop in the pneumatic capacity are. It achieves its supercritical status primarily from. When designing a muffler for any application there are several. Muffler design there are numerous variations of the two main types of muffler designs commonly used, namely absorptive and reactive. Advanced twostroke tuned exhaust system the challenge the society of automotive engineers clean snowmobile challenge 2002 sae csc 2002 is an engineering design competition for college and university student members of the society of. Based on the experience and theory of acoustics for muffler design for various. Defining the acoustic profile and influencing the powerband exhaust design is a more dynamic science than stringing together a few pipes and tacking on some mufflers. Equations are presented for the attenuation characteristics of singlechamber and multiplechamber mufflers of both the expansionchamber and resonator types, for tuned sidebranch tubes, and for the combination of an expansion chamber with a resonator. The displacement, exhaust valve size, induction system, cam profile, exhaust port design and rpm range all factor into deciding what form the exhaust system should take. Theres a lot of things going on in modern mufflers that helps achieve the sound and performance that we are looking for. However when the optimized muffler was fitted to the aircraft. Generally automotive mufflers will have both reactive and absorptive properties.
Calculate flue gas stack height calculate the specific fuel consumption of your diesel genset. How to calculate muffler size and exhaust pipe diameter. Finally, addressing the muffler design constraints, i. Step 1 in this process is to obtain the unsilenced noise level from the engine manufacturer. Theoretical and experimental investigation of mufflers. Noise transmission loss, geometry modification concept, narrow band frequency, design, muffler, silencer, transfer matrix method, genetic algorithm. Finally, the optimum shape of muffler based on the considered design variables for having maximum noise transmission loss is searched by genetic algorithm method. Its offered by meaux racing heads and you can download it from their website at.
Pdf exhaust stack silencer design using finite element. For a fourstroke engine efr engine firing rate n x cfr step 3. Theoretical and experimental investigation of mufflers with. Since the atomic weight of so2 is double the atomic weight of sulphur, the percentage of the so2 in flue. Mufflers can be tailor made for aggressive sounding exhaust note or a super quiet exhaust note depending on the noise canceling strategy built into the muffler. Therefore muffler design becomes more and more important for noise reduction. In areas b, c, and e the wave is divided and reflected, and when they come together at d the waves are ideally canceled. A welldesigned exhaust system collects exhaust gases from engine cylinders and discharges them as quickly and silently as possible. If they say it will work for your vehicle, it will probably work for your vehicle. A comparison of transmission loss obtained for an eieo muffler with analytical calculations based.
Design of mufflers and silencers noise and vibration short course the sound pressure p and the particle velocity v are the acoustic state variables any acoustic component 1 2 p 1, u 1 p 2, u 2 for any passive, linear component. Mar 11, 2014 billy boat summed up the muffler design process by saying, muffler design is fairly complex. Understanding muffler design and sound absorption strategies. An example of a chambered muffler design is this flowmaster muffler.
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