Abstract: A multi-dimensional computational fluid dynamics (CFD) approach was proposed in this study aiming to calculate the transfer matrix of an engine exhaust muffler in the conditions with and without mean flow. The CFD model of the muffler with absorptive material defined as porous zone was calibrated with the measured noise reduction without mean flow, and was further employed to study the effect of the mean flow on the acoustic performance of the muffler. Furthermore, the exhaust acoustical source was derived from the calculated transfer matrices of six different additional acoustic loads obtained by the proposed CFD approach as well as the measured tail noise based on a multiload least squares method. Finally, the exhaust noise was predicted based on Thevenin’s theorem. The proposed CFD approach was suggested to be able to predict the acoustic performance of a complex muffler considering mean flow (without and with mean flow) and heat transfer, and provide reasonable results of the exhaust noise.

Abstract: In an engine including a cooling fan provided at one end of a drive shaft to cool the engine, a muffler is attached such that a longitudinal direction thereof coincide with a direction of gravity, and a muffler accommodating chamber is formed by a muffler cover. A portion of cooling air generated by the cooling fan is introduced into the muffler accommodating chamber so as to cool the muffler. At the muffler accommodating chamber, a cooling air outlet is provided at an upper end of a cooling passage, such that the waste heat of the muffler is discharged from the cooling air outlet to the outside during the stop of the engine. A cooling air inlet is disposed below the cooling air outlet such that the cooling air flows from the lower side to the upper side of the muffler.

Abstract: Transmission loss (TL) of an elliptical cylindrical chamber muffler having a single side/end inlet and multiple side/end outlet is analyzed by means of the 3-D semi-analytical formulation based upon the modal expansion (in terms of the angular and radial Mathieu functions) and the Green's function. The acoustic pressure response obtained in terms of Green's function is integrated over surface area of the side/end ports (modeled as rigid pistons) and upon subsequent division by the port area, yields the acoustic pressure response or impedance Z] matrix parameters due to the uniform piston-driven model. The 3-D semi-analytical results are found to be in excellent agreement with the results obtained by means of 3-D FEA (SYSNOISE) simulations, thereby validating the semi-analytical procedure suggested in this work. Parametric studies such as the effect of chamber length (L), angular and axial locations of the ports, interchanging the locations of inlet and outlet ports as well as the addition of an outlet port for double outlet mufflers on the TL performance are reported, thereby leading to the formulation of design guidelines for obtaining muffler configurations exhibiting a broad-band TL spectrum. One such configuration is an axially long chamber having side-inlet and side-outlet ports such that one of the side ports is located at half the axial length on themajor/minor axis and the other side port is located at three-quarters (or one-quarter) of the axial length on the minor/major axis. (C) 2012 Institute of Noise Control Engineering.

Abstract: A muffler for a vehicle may include a main muffler in front of a rear suspension when viewing from a front of the vehicle, a plurality of baffles dividing an interior of the main muffler into a plurality of chambers, an inlet pipe installed substantially at an center of one side of the main muffler and passing through the plurality of the baffles, a discharge pipe installed at a lower side of the other side of the main muffler and passing through the plurality of the baffles, wherein the discharge pipe exhausts an exhaust gas flowed in the inlet pipe to an exterior of the main muffler, an intermediate pipe in fluidic communication with an outlet port of the inlet pipe, and a variable valve selectively opened or closed in response to a back pressure of the exhaust gas from an outlet port of the intermediate pipe.

Abstract: A muffler system can include an exhaust pipe configured to be connected to an exhaust port of an engine, and a muffler containing a catalyst. The muffler is configured to be connected to a downstream side of the exhaust pipe, and can include a first protector stay covering an upper surface of a high-temperature portion of the muffler. The first protector stay creates a front opening and a rear opening between an upper surface of the muffler and front and rear portions of the protector stay. A muffler protector is attached to the protector stay, the muffler protector being configured to cover an upper surface of the muffler.

Abstract: The invention discloses an SCR (Selective Catalytic Reduction) catalytic conversion muffler, which comprises a front cavity body, a carrier cavity body, a back cavity body and an air outlet pipe that are sequentially and coaxially connected, wherein a catalyst carrier is arranged in the carrier cavity body; a catalyst is coated on the catalyst carrier; a porous air inlet pipe is vertically arranged on the front cavity body; through holes which are uniformly and circumferentially arranged are arranged on the pipe wall of the porous air inlet pipe located in the front cavity body The SCR catalytic conversion muffler is characterized in that the bottom of the porous air inlet pipe is hung in the air; and a closed end cover is arranged at the bottom of the porous air inlet pipe According to the SCR catalytic conversion muffler disclosed by the invention, a urea solution is effectively prevented from crystallizing, and the atomization degree of the urea solution is improved Meanwhile, the air inlet pipe is vertically arranged so that the overall structure of the catalytic conversion muffler is more compact, the condition that the catalytic reduction reaction is affected by deposited particles in an exhaust gas flow blocking a carrier passage is avoided While the porous air inlet pipe effectively reduces system noises, the distribution uniformity of reactants in the carrier can be remarkably improved, thereby effectively improving the catalytic conversion of tail gas

Abstract: Disclosed is a muffler assembly including: a) polymeric housing having an interior surface and at least one opening for at least one inlet and one outlet exhaust pipe; b) at least one metal inlet exhaust pipe and at least one metal outlet exhaust pipe positioned within the openings to provide housing-exhaust pipe interfaces; c) a thermal insulating material coating the interior surface of the polymeric housing and extending through the housing-exhaust pipe interfaces; wherein the thermal insulating material seals the muffler assembly at the housing-exhaust pipe interfaces; and wherein the muffler assembly has a leak rate of 105 Liters/minute or less at 4.5 psig pressure. An optional muffler assembly has body mounting adapters attached to the inlet and outlet exhaust pipes and positioned within the openings to provide housing-body mounting adapter interfaces. Also disclosed are processes for manufacturing the muffler assemblies.

Abstract: This paper deal with vehicle fire caused by damage of diesel particulate filter (DPF) on diesel passenger vehicles. In order to reduce particulate matters included exhaust gases, a DPF in the exhaust system were installed diesel vehicles. A DPF was broken by excessively trapped particulate matters, regeneration error with a malfunction of ECU and defect of suction system such as swirl valve. If the DPF was broken, hot exhaust gases was released to the bottom of vehicle and released hot exhaust gases lead to occur the fire through combustible materials around the exhaust system. When a fire happened in the diesel vehicle caused by damage of DPF, silicate inorganic compounds were attached to the exhaust ventilation pipe and muffler. The silicate inorganic compounds were created by DPF combustion consisting of raw material ceramics. If the silicate inorganic compounds attached to the tail pipe in the diesel passenger vehicles, its fire cause will be assumed damage of DPF.

Abstract: A muffler for enhanced arc protection is described. In the case of an internal arc event in an electrical enclosure, the muffler exhausts arc gas and plasma parallel to the enclosure surface, instead of directly forward where persons may be located. The muffler includes perforated plates and baffle plates in its interior space. The perforated plates have offset perforation patterns from one another, and the baffle plates are provided on opposing walls, causing the plasma and gas to make multiple directional changes. The perforated plates also filter the arc gas and plasma. These directional changes and filtering result in an energy reduction from the exhaust, which provides an increased margin of safety. In addition, the muffler provides an adequate level of ventilation in the enclosure, thus keeping the components cool.

Abstract: A compressor assembly having a high velocity muffler system which produces a particle-free compressor pump feed while reducing noise output from the compressor assembly during compressing operations. The high velocity muffler system is maintenance-free and comprises an inertia filter. The compressor assembly uses a method for producing a compressor pump feed and reducing noise during compressing operations by processing a gas through the high velocity muffler system which has an inertia filter and a muffler chamber to produce a compressor pump feed which can be compressed by a pump assembly.

Abstract: Noise control is essential in an enclosed machine room where the noise level has to comply with the occupational safety and health act. In order to overcome a pure tone noise with a high peak value that is harmful to human hearing, a traditional reactive muffler has been used. However, the traditional method for designing a reactive muffler has proven to be time-consuming and insufficient. In order to efficiently reduce the peak noise level, interest in shape optimization of a Helmholtz muffler is coming to the forefront. Helmholtz mufflers that deal with a pure tone have been adequately researched. However, the shape optimization of multi-chamber Helmholtz mufflers that deal with a broadband noise hybridized with multiple tones within a constrained space has been mostly ignored. Therefore, this study analyzes the sound transmission loss (STL) and the best optimized design for a hybrid Helmholtz muffler under a space- constrained situation. On the basis of the plane wave theory, the four-pole system matrix used to evaluate the acoustic performance of a multi-tone hybrid Helmholtz muffler is presented. Two numerical cases for eliminating one/two tone noises emitted from a machine room using six kinds of mufflers (muffler AF) is also introduced. To find the best acoustical performance of a space-constrained muffler, a numerical assessment using a simulated annealing (SA) method is adopted. Before the SA operation can be carried out, the accuracy of the mathematical model has been checked using the experimental data. Eliminating a broadband noise hybridized with a pure tone (130 Hz) in Case I reveals that muffler C composed of a one- chamber Helmholtz Resonator and a one-chamber dissipative element has a noise reduction of 54.9 (dB). Moreover, as indicated in Case II, muffler F, a two-chamber Helmholtz Resonator and a one-chamber dissipative element, has a noise reduction of 69.7 (dB). Obviously, the peak values of the pure tones in Case I and Case II are efficiently reduced after the muffler is added. Consequently, a successful approach in eliminating a broadband noise hybridized with multiple tones using optimally shaped hybrid Helmholtz mufflers and a simulated annealing method within a constrained space is demonstrated.

Abstract: The invention relates to a structurally modified automobile exhaust muffler assembly, which comprises a housing (1), an inlet tube (2) and an outlet tube (3) The structurally modified automobile exhaust muffler assembly is characterized in that a first partition (4) and a second partition (5) are arranged inside the housing (1) and divide an inner cavity of the housing (1) into a first chamber (6), a second chamber (7) and a third chamber (8), the inlet tube (2) penetrates through the first chamber (6) and into the second chamber (7) from a first outer end of the housing (1), the outlet tube (3) penetrates through the third chamber (8) and into the other outer end of the housing (1), the first chamber is filled with a sound absorbing material (6) to form a muffling chamber, two parallel pipes (10) are disposed at the connection of the second chamber (7) with the third chamber (8), and the third chamber (8) forms a Helmholtz resonant chamber by the aid of the pipes (10) The structurally modified automobile exhaust muffler assembly is reasonable in structure, convenient in use, high in practicality, and capable of eliminating noise of high, medium and low frequencies, and has a good muffling effect

Abstract: In this study, detailed temperature and pressure me asurements were performed at the inlet, outlet and outer boundaries of the suction muffler of a hermetic rec iprocating compressor. The measurements were conducted without effecting real phenomena. After experiment al studies, detailed computational fluid dynamic an alysis of the refrigerant flow (isobutane) in the suction muf fler was performed. Experimental pressure and temperature values at the inlet, outlet and outer boundaries of the suction muffler were used as boundary conditio ns. The effect of suction valve (opening and closing) at the exit of the suction muffler has been consid ered. 3- dimensional time dependent calculations were completed when statistically steady state convergence was reached for one crank period. Realizable k-� turbulence model with appropriate parameters, seco nd order discretizations for time and space derivatives and real gas model for isobutane (R600a) were applied f or the numerical analysis. Mesh dependency of the analysis and solver algorithms were also investigated. The results of the numerical analysis has shown tha t the time integrated average of the numerically ca lculated mass flow rate is close to average mass flow rate m easured with a calorimeter test system. Furthermor e thermal mapping inside the suction muffler shows good agree ment with experimental results. Time dependent flo w analysis results inside the suction muffler help to characterize the flow and acoustic function of the muffler which leads to the new and better muffler designs.

Abstract: PURPOSE: A muffler welding apparatus and a muffler manufacturing method using the same are provided to manufacture various types of mufflers by aligning one end of a sub muffler coupled with a catalyst converter CONSTITUTION: A muffler welding apparatus comprises a supporting unit(300), first and second welding units(100,200), an aligning unit(400), and first and second jig tools(500,510) The supporting unit supports a sub muffler(30) from bottom and lifts the sub muffler The first welding unit welds a junction part between the sub muffler and a catalyst converter(20) The second welding unit welds a junction part between the sub muffler and a flange(10) After the sub muffler is set on the supporting unit, the aligning unit presses one end of the sub muffler to the second welding unit before coupling of the catalyst converter A junction part between the sub muffler and the catalyst converter is located on the same line as the first welding unit, and the sub muffler and the flange are located on the same line as the second welding unit The first and second jig tools are coupled to an end of the catalyst converter and an end of the flange, respectively to hold and rotate the catalyst converter and the sub muffler

Abstract: A combined experimental and computational research effort investigated the noise sources of a pneumatic bleed valve used in turbofan engines and developed engineering solutions for attenuating those sources. The experimental effort employed 1/4-scale, rapid-prototyped valve designs which enabled the exploration of a large parameter space. Microphone array systems surveyed the sound and its sources, and Pitot surveys measured the mean velocity downstream of the valve. The numerical code solved the Reynolds-Averaged Navier Stokes (RANS) in both steady and unsteady modes. The research addressed the flow and acoustics of the valve without and with a muffler. The noise of the isolated valve consists of conventional jet noise with strong excess sound originating from the valve exit. The excess sound was traced to vortex shedding by support struts. Streamlining of the struts, aided by computational parametric studies, eliminated this noise component. The noise of the complete valve, with muffler attached, was attenuated by two principal means: using the streamlined struts and adding a honeycomb flow straightener to the muffler cavity. Proper installation of the honeycomb is critical for maximizing noise reduction. The resulting best design achieved a reduction of approximately 8 decibels in perceived noise level.

Abstract: This paper deals with the role of the higher-order evanescent modes generated at the area discontinuities in the acoustic attenuation characteristics of an elliptical end-chamber muffler with an end-offset inlet and end-centered outlet. It has been observed that with an increase in length, the muffler undergoes a transition from being acoustically short to acoustically long. Short end chambers and long end chambers are characterized by transverse plane waves and axial plane waves, respectively, in the low-frequency range. The nondimensional frequency limit k(0)(D-1/2) or k(0)R(0) as well as the chamber length to inlet/outlet pipe diameter ratio, i.e., L/d(0), up to which the muffler behaves like a short chamber and the corresponding limit beyond which the muffler is acoustically long are determined. The limits between which neither the transverse plane-wave model nor the conventional axial plane-wave model gives a satisfactory prediction have also been determined, the region being called the intermediate range. The end-correction expression for this muffler configuration in the acoustically long limit has been obtained using 3-D FEA carried on commercial software, covering most of the dimension range used in the design exercise. Development of a method of combining the transverse plane wave model with the axial plane wave model using the impedance Z] matrix is another noteworthy contribution of this work.

Abstract: The suction process in reciprocating compressors is strongly affected by the valve dynamics and the pulsating flow throughout the suction muffler This paper describes a simplified computational fluid dynamics (CFD) model to simulate the flow through the muffler, suction valve and a small region inside the cylinder The proposed method is applied to predict the suction process of a small reciprocating compressor and its adequacy is compared with a more time elaborate model in terms of accuracy, computation cost and usability

Abstract: The noise and vibration of a rotary compressor, a type of multi-input, single output system, are generally studied through frequency analysis. Although this method is effective in analyzing frequency components, using this method to identify the specific source of the noise (4 kHz to 6 kHz) is difficult. Hence, noise source should be studied systematically. In this study, a coherence analysis method based on systems analysis is used to identify the compressor noise source. Compressor noise source is identified through the coherence between the vibration signals on the shell of the compressor and the noise signal at one point near the compressor (1 m away from the compressor). A one-third octave band is employed for frequency analysis. The design of experiment is conducted to identify possible noise factors, such as volume, size, and neck area of the resonator in the compressor cylinder. Analysis showed that noise was generated from the cavity of the cylinder and the muffler inside the rotary compressor. A new type of muffler was applied to the rotary compressor to verify this finding. Noise was dramatically reduced.

Abstract: PROBLEM TO BE SOLVED: To provide an exhaust emission purifying system of an internal combustion engine in which at least a part of a catalytic converter is accommodated in an exhaust muffler and which is capable of activating a catalyst faster.SOLUTION: At a downstream end of a downstream side exhaust pipe 30A in an exhaust muffler 29A, an exhaust gas lead-out opening 44A is provided so as to open in a direction toward a part of an upstream side exhaust pipe 28 accommodated within an exhaust muffler 29.

Abstract: Air compressor is a device used to compress the air for various operations, in mining, petrochemical indus- tries, food industries and textile industries. Mufflers are installed to reduce noise where large quantities of high pressure air or gas are discharged into the open air. In this paper CFD analysis technique is used to modify the existing geometry of muffler and noise reduction with allowable backpressure is achieved.

Abstract: A tail pipe assembly for a vehicle includes a tail pipe mounted to a muffler of the vehicle and discharging exhaust gas and condensation water to an outside, and at least one main collecting element that is mounted within the tail pipe, suppresses flow of the condensation water and temporarily stores the condensation water.

Abstract: The invention discloses a welding device for an automobile muffler, which is used for welding the muffler with exhaust pipes at two ends of the muffler. The welding device comprises a base, a muffler connecting mechanism, exhaust pipe connecting mechanisms and a welding torch connecting mechanism, wherein the muffler connecting mechanism is arranged on the base, the exhaust pipe connecting mechanisms arranged on the base are positioned on two opposite sides of the muffler connecting mechanism respectively, and the welding torch connecting mechanism is arranged on the base. The muffler is transversely fixed onto the muffler connecting mechanism, the exhaust pipes are transversely fixed onto the exhaust pipe connecting mechanisms, two welding torches aligned to the connection positions of the muffler and the exhaust pipes respectively are arranged on the welding torch connecting mechanism, and a driving motor is arranged on the base and used for driving the muffler connecting mechanism and the exhaust pipe connecting mechanisms to rotate synchronously through a transmission mechanism. By the aid of the technical scheme, the muffler is synchronously welded with the exhaust pipes at the two ends of the muffler by means of rotation of the corresponding mechanisms, the welding device is simple in operation, high in welding efficiency and fine in welding quality, and defects caused by manual welding are avoided.

Abstract: The invention relates to a engine, specially, relates to an air-powered engine assembly which uses the compressed air as the complementary power source. The air-powered engine assembly of the present invention includes an engine body (1), a multiple-column power distributor (2), a power equipment (4), a controller system (6), an intake speed control valve (23), a high pressure gas tank set (13), a constant pressure tank (16), an electronic control unit ECO (29) and a complementary compressed air circuit. The complementary compressed air circuit includes an air compressor (7), a condenser (11), a pressure limiting valve (702), sequence valve (705), an exhaust gas recycle tank (9), an electro-drive turbine unidirectional suction pump (19) and an exhaust gas muffler (22).

Abstract: A method and an arrangement for cleaning a particulate filter in a vehicle provided with an internal combustion engine is provided. The particulate filter is mounted in an operative position inside an exhaust muffler under normal operation of the engine. The method involves performing a cleaning process including disassembling and removing the particulate filter from a first end of the muffler; reversing and reassembling the particulate filter a cleaning position at the first end of the muffler; starting and operating the engine by controlling the engine speed according to a predefined cycle until a predetermined condition is fulfilled; and stopping the engine and returning the particulate filter to its operative position inside the exhaust muffler.

Abstract: Automobile noise contains a variety of different noise. It can be divided into the engine noise and chassis of noise. The engine noise is main noise sources of automobile noise, and can be roughly divided into pneumatic noise, combustion noise, and mechanical noise. These are caused by the recruit vibration of the students in air, when a car engine exhausts fan rotation, these voices, the light into the air directly. No, the largest into exhaust muffler for automobile engine exhaust noise, another kind is the source of the intake noise. Fan noise, usually main noise sources especially air-cooled engine. Combustion noise, mechanical noise is difficult to disaggregate. Study on emission of vehicle noise frequency characteristics and energy distribution characteristics, with the optical image automatic overlapping, obtained the vehicle noise source frequency, spatial location and origin. The test results show that, the microphone array technology is an effective way for noise diagnosis and sound localization, for noise control of vehicle to provide a scientific basis.

Abstract: The invention relates to a muffler, in particular to an impedance composite muffler, which comprises a primary muffler unit and a secondary muffler unit. The secondary muffler unit is made of lava, a shell encircles to form a cavity of the secondary muffler unit and is divided into an inlet-side cavity and an outlet-side cavity, the primary muffler unit is positioned in the inlet-side cavity and consists of an inner tube, one end of the inner tube is communicated with an inlet, the other end of the inner tube is connected with the secondary muffler unit, an integral row of primary holes is arranged on the inner tube, the inside and the outside of the inner tube are communicated with each other via the primary holes, an airflow channel is disposed on the secondary muffler unit, one end of the airflow channel is communicated with the inlet-side cavity between the inner tube and the shell, and the other end of the airflow channel is communicated with the outlet-side cavity. The impedance composite muffler has the advantages that an excellent muffler performance can be realized by means of combining an expansion muffler effect, a throttling pressure reduction muffler effect and a sound absorption effect, and the impedance composite muffler is convenient in processing and maintenance, low in manufacturing cost and fine in structural performance and aerodynamic performance. The impedance composite muffler is applicable to muffling of exhaust of engines and the like.