Exhaust System Of Internal Combustion Engine Research Articles

Method for design and evaluation of ICE exhaust silencers

The noise levels generated by an unmuffled engine exhaust system can be identified as the loudest vehicle noise source. The muffler or silencer is an essential component of the internal combustion engine exhaust system. Its main function is to reduce the exhaust-generated noise to an acceptably low level. Its design development is a complex process affecting the engine efficiency and thus fuel consumption, emissions and overall noise generation. This paper focuses on the design development of a muffler for a single-cylinder engine application. A 1D GT-Power model of a single valve engine was developed. Additionally, an analytical muffler preliminary design methodology was introduced. The methodology provides guidelines for muffler grade selection, sizing of different components, and calculation of backpressure as a function of the exhaust gas flow rate. Two custom mufflers design concepts were developed for the single-cylinder engine based on the introduced analytical methodology. Two commercial single-cylinder engine muffler designs available from Yanmar and Loncin were considered for the engine performance evaluation simulation. The presented combination of analytical and numerical modelling procedures can reduce the overall length of the muffler development stage by eliminating faulty design concepts and refining the muffler's performance parameters.

Numerical and Experimental Analysis of the Effect of Acoustic Loads on the Source Characterization for an Internal Combustion Engine Exhaust System

The identification of source characteristics, commonly characterized as the source strength and source impedance, is essential for predicting the acoustic performance of an internal combustion (IC) engine exhaust system. This study contributes to a theoretical analysis of the effect of the acoustic parameters of loads (i.e., four-pole parameters, load impedance, and radiation impedance of the tailpipe) on the identification error of the source characteristics for an IC engine. A model based on the linear time-invariant hypothesis was constructed. A dispersion estimation function of the source strength and a deviation estimation function of the source impedance were established as indicators to test the identification accuracy. A three-dimensional (3D) multifield coupling numerical simulation method, which can thoroughly consider the influences of airflow and temperature, was applied to obtain the acoustic parameters of loads and compare them with those obtained by a one-dimensional (1D) analytical method. Then, the acoustic parameters of loads and the radiated sound pressure level of the tailpipe obtained in the measurement were substituted into the source characteristics identification model. Based on the analysis and calculation, the estimated error of the source characteristics acquired by using the 3D numerical simulation method is significantly lower than that by using the 1D analytical method. Moreover, the experiment and the 3D multifield coupling numerical simulation method were used to verify the identification results of the engine source characteristics. The results show that the far-field sound pressure level of the tailpipe predicted via the 3D numerical simulation method agrees well with the experimental results, indicating that accurate acoustic parameters of loads can effectively improve the source identification accuracy for an IC engine.

Heating system for measuring tanks of the cementing unit from the exhaust system of the base chassis

The purpose of this article is to increase the efficiency of the design process and reduce the cost of field experiments by using numerical analysis methods of the dimensional capacity heating efficiency of the internal combustion engine exhaust system. To solve the problem, a non-stationary nonlinear solver of gas dynamic processes (Siemens STAR-CCM+) was used, which allows to evaluate the correctness of the problem statement, significantly reducing the cost of full-scale tests. The paper considers the heating of a dimensional two-section tank in the layout of the cementing unit on the chassis with a triplex high-pressure pump and a drive from the power take-off box on the gear box of the chassis engine. The exhaust pipe structurally passes inside the measuring tank. According to the research results obtained graphic dependences of temperature change of liquid measuring cups to control points, the distribution of temperature field of the liquid in a volumetric tank, distribution of the temperature field of the surrounding air, stream lines and velocity field of the ambient air and the exhaust gases of internal combustion engines. The results of the calculations clearly show that the application of the method of heating the measuring capacity by entering the exhaust pipe directly into the liquid can be considered effective.

Effectiveness analysis of external heating system of gauge tank of pumping unit using exhaust piping of the IC engine

Introduction. The heating efficiency or regulation of the operating temperature of the fluid located in the gauge tank of a mobile pumping unit (PU) using the exhaust system of the internal combustion engine (ICE) is studied. The paper objective is to improve the design process and to reduce costs of field experiments. Materials and Methods . To solve this problem, numerical analysis methods were used when calculating the heating systems of the gauge tank with the external location of the pipeline from the ICE exhaust system by the example of the widely used installations (TsA-320, UNB, AChF, etc.). Siemens STAR-CCM+, a non-stationary non-linear solver of gas-dynamic processes, was used, which evaluates the correctness of the problem statement and reduces significantly the costs of full-scale field tests. Research Results. The study was conducted for the operating conditions of the cementing unit on the Kamaz-43118 chassis with the SIN-32 pump and a drive from the power take-off attachment on the gearbox of the chassis engine. In the calculation model, a convection-type heat transfer was applied between the body of the gauge tank and the surrounding air; between the body of the gauge tank and the liquid; between the chassis exhaust system duct and ambient air; between the exhaust system duct and exhaust gases. The following study results were obtained: characteristic curves of the temperature variation of the gauge tank liquid at the watch points; the distribution of the temperature field of the liquid in the gauge tank; the distribution of the ambient air temperature field; lines of flows and ambient air speed field and of the ICE exhaust gases. Discussion and Conclusions . The study has revealed poor effectiveness of the considered structure. The data analysis allows us to offer an improved design of the gauge tank heating. The results obtained in the work can be used in the calculations of such devices used in the hydraulic fracturing units and grout machines.

Study of SI engine fueled with methanol vapor and dissociation gas based on exhaust heat dissociating methanol

To improve the fuel efficiency of internal combustion (IC) engine and also achieve the goal of direct usage of methanol fuel on IC engine, an approach of exhaust heat dissociating methanol was investigated, which is a kind of method for IC engine exhaust heat recovery (EHR). A bottom cycle system is coupled with the IC engine exhaust system, which uses the exhaust heat to evaporate and dissociate methanol in its catalytic cracker. The methanol dissociation gas (including methanol vapor) is used as the fuel for IC engine. This approach was applied to both naturally aspirated (NA) engine and turbocharged engine, and the engine performance parameters were predicted by the software GT-power under various kinds of operating conditions. The improvement to IC engine performance and the conversion efficiency of recovered exhaust gas energy can be evaluated by comparing the performances of IC engine fueled with various kinds of fuels (or their compositions). Results show that, from gasoline engine, methanol vapor engine to dissociated methanol engine, the full load power decreases successively in the entire speed area due to the declining of volumetric efficiency, while it is contrary in the thermal efficiency at the same brake mean effective pressure (BMEP) level because of the improving of fuel heating value. With the increase of BMEP, the conversion efficiency of recovered exhaust gas energy is promoted. All those results indicate that the approach of exhaust heat dissociating methanol has large energy saving potential with great application prospect to IC engines.

Исследование акустических характеристик глушителей шума выпуска автотранспортных двигателей внутреннего сгорания

The main acoustic characteristic of noise muffler–"brought losses", which shows the decrease of noise created by its source, in particular by exhaust system of internal-combustion engine, in a control point as a result of muffler use is considered. The explanation of essence of this characteristic and its mathematical description are offered; the empirical dependences for calculation of sound radiation impedance by exhaust system end opening are given. The offered way of release noise source impedance definition seems to be more reliable in comparison with already known ones as it allows to consider oscillatory processes in the exhaust manifold of internal-combustion engine thanks to which the calculation accuracy of muffler’s brought losses in course of its development at motor transport engines design stage is increased. The analytical dependences for calculation of frequencies at which the extreme values of this characteristic are observed are also received.

A Nonlinear Quasi-3D Approach for the Modeling of Mufflers with Perforated Elements and Sound-Absorbing Material

Increasing demands on the capabilities of engine thermo-fluid dynamic simulation and the ability to accurately predict both performance and acoustics have led to the development of several approaches, ranging from fully 3D to simplified 1D models. The quasi-3D approach is proposed as a compromise between the time-demanding 3D CFD analysis and the fast 1D approach; it allows to model the acoustics of intake and exhaust system components, used in internal combustion engines, resorting to a 3D network of 0D cells. Due to its 3D nature, the model predicts high-order modes, improving the accuracy at high frequencies with respect to conventional plane-wave approaches. The conservation equations of mass and energy are solved at cell centers, whereas the momentum equation is applied to cell connections including specific source term to account for the of sound-absorbing materials and perforated elements. The quasi-3D approach has been validated by comparing the predicted transmission loss to measured data for a number of standard configurations typical of internal combustion engine exhaust systems: a reverse-flow chamber and series chambers with perforates and resistive material.

The Design and Analysis of Closed-Coupled Exhaust Manifold

The layout of closed-couple catalyst converter in internal combustion engine exhaust system is one of important way to reduce vehicle emission. CFD method based on finite volume method is adopted to numerical simulate flow distribution in the entrance of closed-coupled catalytic converter and applying business software of FLUENT to clarity the flow uniformity of inlet to ensure catalytic converter work efficiently and meet regulations. The flow field uniformity of entrance were studied and analyzed. Research finds that the shape of manifold has effect on dispersion of velocity in entrance and dispersion of velocity has a relatively strong correlation with pulsation flow. The flow reverse in junction deflect the air flow that flow into the entrance of closed-couple catalyst converter. Calculation results indicate that the uneven rate coefficient is 0.266 and volatility is 0.515 in the entrance of closed-couple catalyst.

Improving engine performance and noise level, using the ALBEA simulation technique

The article deals with the technology of engine operation simulation, including intracylinder processes, gas exchange, mechanical losses and gas dynamic noise simulation. This technology is exemplified by a design of a four-stroke internal combustion engine exhaust system. This paper describes the configuration of a designed exhaust system that allowed the engine exhaust noise level to be lowered and its power and fuel consumption parameters to be improved. The results, based on the comparison of simulated and experimental data with the designed exhaust system, are given. These results confirm a high reliability of the applied models. There are also presented, results of the numerical research of the engine exhaust noise when the throttle is closed fast. It has been shown that the exhaust noise increase in throttle closing is caused by a return gas flow.

Experimental Investigation of Active Noise Controller for Internal Combustion Engine Exhaust System

Two active noise control (ANC) algorithms for internal combustion engine exhaust systems are developed and their performances are compared in various experiments. The first controller is based on the filtered-x least mean square (FXLMS) algorithm with feedback neutralization, while the second is a fixed controller with a gain-scheduled active control technique for broadband attenuation with thermal effects. Both control algorithms are implemented on a digital signal processing (DSP) platform. Experiments are carried out to evaluate the attenuation performance of the proposed active noise control systems for an engine exhaust system. The results of the experiments indicate that both the adaptive controller and the gain-scheduled controller effectively suppress the noise of engine exhaust systems. The experimental comparison and analysis of the proposed controllers are also described.

High performance muffler

A high performance muffler is used to modify sound waves of exhaust gases generated by a high performance internal combustion engine. The muffler has an inlet for connection to an internal combustion engine exhaust system. A muffler body is connected to the inlet. The muffler body has a shell which has a width greater than its height. The shell includes a pair of spaced apart opposed panels. An outlet is connected to the muffler body to receive exhaust gases from the body. The muffler body has a first expansion chamber adjacent to the inlet. The first expansion chamber extends across the width of the muffler body. A first reduced opening is in the muffler body extending across the width of the muffler body. A second expansion chamber is in the muffler body adjacent to the first reduced opening. The second expansion chamber also extends across the width of the muffler body. A second reduced opening extending across the width of the muffler body communicates with the second expansion chamber. The second reduced opening and first reduced opening cooperate to direct flow of the exhaust gases through the muffler body in a sinuous path. A third expansion chamber extends across the width of the muffler body and is positioned adjacent to the second reduced opening. The third expansion chamber communicates with the outlet so that gases flowing in the sinuous path are exhausted from the muffler body.

Estimation of velocity fluctuation in internal combustion engineexhaust systems through beamforming techniques

The knowledge of the particle velocity fluctuations associated withacoustic pressure oscillation in the exhaust system of internal combustionengines may represent a powerful aid in the design of such systems, from thepoint of view of both engine performance improvement and exhaust noiseabatement. However, usual velocity measurement techniques, even if applicable,are not well suited to the aggressive environment existing in exhaust systems.In this paper, a method to obtain a suitable estimate of velocity fluctuationsis proposed, which is based on the application of spatial filtering (beamforming) techniques to instantaneous pressure measurements. Making use ofsimulated pressure-time histories, several algorithms have been checked bycomparison between the simulated and the estimated velocity fluctuations.Then, problems related to the experimental procedure and associated with theproposed methodology are addressed, making application to measurements made ina real exhaust system. The results indicate that, if proper care is taken whenperforming the measurements, the application of beamforming techniques gives areasonable estimate of the velocity fluctuations.

Experimental study of rasping noise in internal combustion engine exhaust systems

The abnormal noise, known as rasping noise by several exhaust muffler designers, is a metallic intermittent noise which irritates the ear and has an adverse effect on vehicle marketability. It occurs in small cars having no more than two boxes in their exhaust systems. This phenomenon is highly noticed during a rapid acceleration or deceleration in cold conditions. However, it is sharply attenuated when the exhaust system is warmed up. An experimental study has been undertaken. Several exhaust systems, ranging from a simple pipe to a complete exhaust line, are tested. Pressure measurements in the line are performed by piezoelectric transducers. The tail pipe noise measurements are performed by a microphone. It has been observed that, unlike the usual exhaust noise that contains essentially second and fourth orders, the perception of the so-called rasping noise is associated with high-frequency components in the signal and needs higher-order analysis to be fully characterized. The experiments also show the steepening of the waves when rasping noise is listened. The high axial temperature gradient causes an increasing of that effect and probably a generation of shock waves which excite the main muffler and cause the metallic noise.

Calculation of path line streams

This paper describes the theoretical and experimental work on the unsteady flow from the cylinder through the exhaust pipe of a reciprocating spark ignition engine. The theoretical work covers the subject of unsteady gas dynamics applied to an internal combustion engine exhaust system. The new development presented here concerning the internal combustion engine simulation is that the computation uses path lines and introduces path line streams. The objectives were to develop a capability of tracing and retaining the identity of the path lines in the exhaust system of an internal combustion engine. Time-resolved hydrocarbon measurements were made in the cylinder and in the exhaust system of a spark ignition engine using fast acting sampling valves. In order to study the mechanisms by which the hydrocarbon mole fraction is reduced in the transport from the cylinder to pipe, the path line calculation in conjunction with a post flame oxidation model was applied to this situation.

Primena numeričkih metoda za predikciju buke izduvnog sistema motora SUS

Primena numeričkih metoda za predikciju buke izduvnog sistema motora SUS

The radiation of sound from an engine exhaust

Internal combustion engine exhaust system sound radiation, discussing pressure wave effects, energy flux and boundary conditions

Acoustical Analysis Applied to Internal Combustion Engine Exhaust Systems of Conical Form

In the following analysis the variation of the charging capacity of a small two-stroke motor-cycle engine is utilized to assess the non-steady flow characteristics of conical exhaust pipes having different length and divergence. The performance of the engine under the most favourable conditions is applied to determine the natural frequency of exhaust ducts fitted with conical portions. The experimental data yielded are compared with theoretical computations based on acoustical treatments and inspection of the results obtained supports the conclusion that the ports behave as a partly, and not as a fully, closed end as commonly accepted.

Paper 10: A Computer Program for Calculating the Performance of an Internal Combustion Engine Exhaust System

The paper describes the method of presenting data for a computet program, based on the method of characteristics, which calculates the pressure and temperature in the exhaust system and cylinders in two- or four-stroke engines with valves or ports. The program is arranged so that the performance of an exhaust pipe can be assessed for a number of pipe configurations. A brief description of the theoretical background and program format is given, followed by a suggested design calculation procedure. Examples are then given of the application of the program to both two- and four-stroke supercharged engines. The results of the calculation are compared with experimental measurements. A description of the subroutines and the organization of a calculation on the computer, together with the data order are given in two of the appendices.