• Transactions of the Korean Society of Automotive Engineers
• /
• v.15 no.1
• /
• pp.139-145
• /
• 2007

This paper presents the low cycle thermal fatigue of the engine exhaust manifold subject to thermomechanical cyclic loadings. The analysis includes the FE model of the exhaust system, temperature dependent material properties, and thermal loadings. The result shows that at an elevated temperature, large compressive plastic deformations are generated, and at a cold condition, tensile stresses are remained in several critical zones of the exhaust manifold. From the repetitions of thermal shock cycles, plastic strain ranges could be estimated by the stabilized stress-strain hysteresis loops. The method was applied to assess the low cycle thermal fatigue for the engine exhaust manifold. It shows a good agreement between numerical and experimental results.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.4
• /
• pp.56-62
• /
• 2008

A synthetic gas reformed from hydrocarbon-based fuels consists of $H_2$, CO and $N_2$. Hydrogen contained in the synthetic gas is a very useful species in chemical processes, due to its wide flammability range and fast burning speed. The ESGI (Exhaust Synthetic Gas Injection) technology is developed to shorten the light-off time of three way catalysts through combustion of the synthetic gas in the exhaust manifold during the cold start period of SI engines. Before the ESGI technology is applied to the test engine, the authors set a test rig that consists of gas temperature and composition controllers, an exhaust pulse generator and an exhaust manifold with a visualization window, in order to optimize the point and conditions of injection of the synthetic gas. Through measuring burned gas temperatures and taking photographs of synthetic gas combustion at the outlet of the exhaust manifold, the authors tried to find the optimal injection point and conditions. Analysis of burned gas composition has been performed for various $O_2$ concentrations. As a result, when the synthetic gas is injected at the port outlet of the cylinder No. 4 and $O_2$ concentration exceeds 4%, combustion of the synthetic gas is strong and effective in the exhaust manifold.

• International Journal of Automotive Technology
• /
• v.5 no.4
• /
• pp.297-302
• /
• 2004

This paper presents the low cycle thermal fatigue of the engine exhaust manifold subject to thermo-mechanical cyclic loading. As a failure of the exhaust manifold is mainly caused by geometric constraints of the less expanded inlet flange and cylinder head, the analysis is based on the exhaust system model with three-dimensional temperature distribution and temperature dependent material properties. The result show that large compressive plastic deformations are generated at an elevated temperature of the exhaust manifold and tensile stresses are remained in several critical zones at a cold condition. From the repetition of these thermal shock cycles, maximum plastic strain range (0.454%) could be estimated by the stabilized stress-strain hysteresis loops. It is used to predict the low cycle thermal fatigue life of the exhaust manifold for the thermal shock test.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.18 no.6
• /
• pp.7-13
• /
• 2010

In this study, we investigated the efficient FE modelling techniques for thermal stress analysis of the exhaust manifold subject to thermo-mechanical cyclic loadings. At first, full engine model was considered to identify the critical locations and their results were compared to failure site shown by the engine bench test. And the equivalent system model was proposed based on the mechanical behavior of the full engine model. The weak areas of both FE models show a good agreement with the experimental crack location. As a result, a simplified modelling methodology was verified to estimate the thermo-mechanical behaviors of the exhaust manifold under thermal shock test condition.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.5
• /
• pp.1-8
• /
• 1999

This paper describes the method for detection of the misfired cylinder by analysis of the variation of pressure occurred in exhaust manifold on an MPI gasoline engine. Misfired cylinder(s) cause a loss of power, an increase of fuel consumption and exhaust emission and vibration is caused by unsteady torque. Therefore early detection and correction of misfired cylinder(s) play a very important role in the proper performance and the exhaust emission. The method is a comparison of integration pressure index during the period of a blowdown in the displacement period. Experimental results showed that the method, using the variation of pressure in the exhaust manifold is proven to be effective in the detection of single cylinder or multiple cylinders misfire on the gasoline engine regardless of the engine revolutions. In addition, this method, using the variation of pressure in the exhaust manifold is a very easy and accurate method compared with other methods.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.15 no.3
• /
• pp.160-165
• /
• 2007

Exhaust manifold is generally subjected to thermal cycle loadings ; at hot condition, large compressive plastic deformations are generated, and at cold condition, tensile stresses are remained in highly deformed critical zones. These phenomena originate from that thermal expansions of the runners are restricted by inlet flange connected to the cylinder head, because the former is less stiff than the latter and, the temperature of the inlet flange is lower than that of the runners. Therefore, due to the repetitions of thermal deformation, leakage problems could be occur between inlet flange and cylinder head. In this study, we obtained pressure distributions along gasket bead lines from the finite element analysis and compared to the test results. It shows a good agreement between numerical and experimental results.

• Proceedings of the KSME Conference
• /
• 2000.11b
• /
• pp.751-756
• /
• 2000

Based on Experimental analysis, the characteristics of back pressure in automotive exhaust system is tested for 4-stroke gasoline engine. The back pressure in automotive exhaust system is generated by resistance working of exhaust system, i.e. exhaust manifold, pipe length, pipe banding, difference system pressure with atmospheric pressure. This paper contains experimental results which are tested for the change of exhaust pipe length and torque change are tested under experimental conditions.

• International Journal of Automotive Technology
• /
• v.8 no.5
• /
• pp.575-581
• /
• 2007

As current and future automobile emission regulations become more stringent, the research on flow distribution for an exhaust manifold and close-coupled catalyst(CCC) has become an interesting and remarkable subjects. The design of a CCC and exhaust manifold is a formidable task due to the complexity of the flow distribution caused by the pulsating flows from piston motion and engine combustion. Transient flow at the exhaust manifold can be analyzed with various computational fluid dynamics(CFD) tools. However, the results of such simulations must be verified with appropriate experimental data from real engine operating condition. In this study, an experimental approach was performed to investigate the flow distribution of exhaust gases for conventional cast types and stainless steel bending types of a four-cylinder engine. The pressure distribution of each exhaust sub-component was measured using a simulated dynamic flow bench and five-hole pitot probe. Moreover, using the results of the pitot tube measurement at the exit of the CCC, the flow distribution for two types of manifolds(cast type and bending type) was compared in terms of flow uniformity. Based on these experimental techniques, this study can be highly applicable to the design and optimization of exhaust for the better use of catalytic converters to meet the PZEV emission regulation.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.2
• /
• pp.23-28
• /
• 2014

This study investigates fluid flow and thermal stress at automotive exhaust manifolds as model 1 and 2. The maximum displacements happen at joint part connected with 4 pipes and upper middle of both parts in cases of model 1 and 2 respectively. At inner surface of the part connected with engine, maximum equivalent stresses of 991.85 and 698.96 MPa are shown in cases of model 1 and 2 respectively. As maximum velocities at the outlet at model 1 are shown at 19.46 and 14.61 m/s in cases of model 1 and 2 respectively, model 1 has more pressure drop than model 2. As result, model 2 has less pressure drop than 1. Model 2 has less deformation and stress than model 1. Model 2 has also less pressure drop than model 1. Therefore model 2 has more strength durability than model 1. This study result is applied with the design of safe automotive manifold and it can be useful to improve the durability by predicting prevention against the deformation due to exhaust gas.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2008.05a
• /
• pp.209-212
• /
• 2008

Hydroforming Technology has been applied to manufacture in various parts of automobile. Especially, Exhaust manifold has been applied to hydroforming method in the foreign advanced automotive company. Exhaust manifold runner is important exhaust parts that heat-resistant and exhaust flow characteristics are requested in the automobile. The purpose of this study is to optimize the manufacturing method of exhaust maniflold runner using FEA and to propose to get a optimization design direction. In addition, Comparative analysis between conventional exhaust maniflold and hydroformed exhaust maniflold has been done in view of weight-saving, manufacturing advantage.