Engine Exhaust Manifold Research Articles

Combustion and emission characteristics of DI diesel engine fuelled by ethanol injected into the exhaust manifold

Dual fuel diesel engine operation is an important technique used for combustion control in diesel engines. In this study, ethanol is injected into the exhaust manifold of a single cylinder diesel engine. The exhaust valve opens during the intake stroke, enabling vaporized ethanol to enter the cylinder where it is then ignited by diesel fuel injection. The effects of exhaust gas recirculation (EGR) ratios, ethanol injection timing, and ethanol amount are studied. Furthermore, exhaust and intake manifold injection of ethanol compared under the same conditions. These results reveal that ethanol injection into the exhaust manifold increases the apparent heat release rate (AHRR) at the premixed combustion phase. Additionally, the ignition delay increases with ethanol injection by 0.2° crank angle (CA). The indicated mean effective pressure (IMEP) and total heat released per cycle are increased by 8.2% and 14.2%, while the NOx and soot concentrations are reduced by 88% and 30%, respectively. When compared with exhaust manifold ethanol injection, intake manifold injection results in higher AHRR in the premixed combustion phase, decreased engine performance, an increase in soot production of approximately 35%, and decrease in NOx of 13%.

Effect of fin attachment on thermal stress reduction of exhaust manifold of an off road diesel engine

The effect of fin attachment on the thermal stress reduction of exhaust manifold of an off road diesel engine (Komatsu HD325-6) was investigated. For doing this, coupled thermo-fluid-solid analysis of exhaust manifold of the off road diesel engine was carried out. The thermal analysis, including thermal flow, thermal stress, and the thermal deformation of the manifold was investigated. The flow inside the manifold was simulated and then its properties including velocity, pressure, and temperature were obtained. The flow properties were transferred to the solid model and then the thermal stresses and the thermal deformations of the manifold under different operating conditions were calculated. Finally, based on the predicted thermal stresses and thermal deformations of the manifold body shell, two fin types as well as body shell thickness increase were applied in the critical induced thermal stress area of the manifold to reduce the thermal stress and thermal deformation. The results of the above modifications show that the combined modifications, i.e. the thickness increase and the fin attachment, decrease the thermal stresses by up to 28% and the contribution of the fin attachment in this reduction is much higher compared to the shell thickness increase.

Exhaust Energy Recovery with Turbo Compounding in a Heavily Downsized Engine

Large amount of heat energy is wasted in Internal Combustion (IC) engine through the exhaust manifold, coolant, convective and radiative heat transfer. Significant amount of thermal energy waste occurring at the exhaust manifold of the IC engine can be recovered using various contemporary heat recovering techniques. The paper presented the viability of using turbo compounding waste heat recovering technique in recovering a significant amount of waste energy occurring at the exhaust of a heavily downsized engine. Electric turbo compounding (ETC) simulation using Ford Eco-Boost base line engine with modification using Hy-Boost modelled with AVL Boost software was carried out for the analysis. The simulation results show a 3% reduction in Brake Specific Fuel Consumption (BSFC), 0.5 bar Brake Mean Effective Pressure (BMEP) increase and up to 2 kW of power output were realized at engine speed of 2500 rpm. The result clearly indicates the effectiveness, viability and commercialization potentials of this waste heat recovery technique.

Modified pressure loss model for T-junctions of engine exhaust manifold

The T-junction model of engine exhaust manifolds significantly influences the simulation precision of the pressure wave and mass flow rate in the intake and exhaust manifolds of diesel engines. Current studies have focused on constant pressure models, constant static pressure models and pressure loss models. However, low model precision is a common disadvantage when simulating engine exhaust manifolds, particularly for turbocharged systems. To study the performance of junction flow, a cold wind tunnel experiment with high velocities at the junction of a diesel exhaust manifold is performed, and the variation in the pressure loss in the T-junction under different flow conditions is obtained. Despite the trend of the calculated total pressure loss coefficient, which is obtained by using the original pressure loss model and is the same as that obtained from the experimental results, large differences exist between the calculated and experimental values. Furthermore, the deviation becomes larger as the flow velocity increases. By improving the Vazsonyi formula considering the flow velocity and introducing the distribution function, a modified pressure loss model is established, which is suitable for a higher velocity range. Then, the new model is adopted to solve one-dimensional, unsteady flow in a D6114 turbocharged diesel engine. The calculated values are compared with the measured data, and the result shows that the simulation accuracy of the pressure wave before the turbine is improved by 4.3% with the modified pressure loss model because gas compressibility is considered when the flow velocities are high. The research results provide valuable information for further junction flow research, particularly the correction of the boundary condition in one-dimensional simulation models.

Parametric study of the effects of the design factors on the performance of a heat recovery system obtained from an exhaust gas in a gasoline engine

A parametric study was conducted to determine the optimum operating conditions of a waste heat recovery system obtained from the exhaust gas. An analysis of the Rankine cycle was also performed with respect to the changes in the evaporation pressure and the mass flow rate of the working fluid, which have a significant influence on the performance of a heat recovery system. The analysis conditions in this study were selected on the basis of the mass production of an actual waste heat recovery system attached to a real engine exhaust manifold, and the energy flow obtained from gasoline engines was analysed using the first and second laws of thermodynamics. A model for analysing the heat exchanger was also developed using the experimental data on heat transfer between the actual exhaust gas and the working fluid. Based on this model, a cycle analysis of the waste heat recovery system was conducted through one-dimensional simulation. The optimum operating conditions and waste heat recovery system performance were determined from the analytical results. In addition, the potential of the heat recovery system was evaluated by investigating the brake specific fuel consumption of a gasoline engine equipped with a waste heat recovery system.

Cracking Failure Analysis and Optimization on Exhaust Manifold of Engine with CFD-FEA Coupling

Cracking Failure Analysis and Optimization on Exhaust Manifold of Engine with CFD-FEA Coupling

Study on the Unsteady Heat Transfer of Engine Exhaust Manifold Based on the Analysis Method of Serial

Study on the Unsteady Heat Transfer of Engine Exhaust Manifold Based on the Analysis Method of Serial

Heat Transfer Analysis of Exhaust Manifold with Water Jacket of a High Speed Gasoline Based on FSI

The fluid-structure interaction (FSI) method is employed to analyze heat transfer of a exhaust manifold with a water jacket. Three different turbulence models are valued to predict their spheres of application. The mutual effect on complex flow distribution and heat transfer with and without transition is also considered respectively. The results show that reasonable turbulence model and transition will contribute to a better numerical precision of temperature distribution. Considering transition will have a impact on the design of novel exhaust manifold of high speed gasoline engine. In addition, numerical results can be referred to improve the structure.

S0530105 モータリングエンジンにおける曲がり管内排気脈動流の実験的および数値解析的研究([S053]内部流れ)

This paper presents experimental and numerical investigations of pulsating flow from an exhaust manifold of an automobile engine. Pulsating exhaust with 1500 rpm flows in S-shaped duct with a square cross section. Thus, velocity fields at first and second bends in a horizontal plane are measured using PIV. It shows that fast flow and slowdown appear around inner and outer walls in both bends, respectively. Numerical simulations using RNG k-e model are in good agreement with measurements. Simulations have also displayed secondary flows grow after passing through the first bend like steady flows, because of pressure gradient and centrifugal force by the duct curvature. However, it is also found that flow direction of the secondary flow at the second bend outlet is opposite to centrifugal force; this result is different from researches of the past. Influences of the intensity of the secondary flows between two bend inlets on flow field are discussed in the present paper.

Development of a Virtual Sensor for Estimation of Gas Temperature in a Diesel Engine Exhaust Manifold

Development of a Virtual Sensor for Estimation of Gas Temperature in a Diesel Engine Exhaust Manifold

Low-cycle Thermal Fatigue and High-cycle Vibration Fatigue Life Estimation of a Diesel Engine Exhaust Manifold

This paper aims at estimating the low-cycle and high-cycle fatigue life of a turbocharged Diesel engine exhaust manifold. First, a decoupled thermo-structural Finite Element analysis has been performed to investigate low-cycle fatigue phenomena due to the thermal loadings applied to the exhaust manifold. High/low temperature cycles causes stress-strain hysteresis loops in the manifold material whose related dissipated energy can be directly correlated to low-cycle thermal fatigue. Afterwards, a dynamic harmonic analysis has been performed aiming at investigating the existence of high-cycle fatigue phenomena due to vibrational loading applied to the exhaust manifold during the duty cycle. Three direction acceleration experimental loadings have been applied to the model. An ad-hoc methodology has been developed to superimpose thermo-structural results to dynamic harmonic analysis results. In particular, quasi-static thermo-structural results have been employed to identify the mean stress values of vibration fatigue cycles, while alternate stress values have been derived from harmonic analysis. Different combinations of frequencies and phases of the acceleration input signals have been considered to create different high-cycle fatigue loadings. Each cyclic load case has been processed employing the multiaxial Dang Van fatigue criterion.

Thermal Stress and Modal Analysis of Engine Exhaust Manifold

The cracking problem of the engine exhaust manifold is studied in this paper. The temperature field and thermal stress are calculated. Meanwhile the modal under the thermal stress are analyzed. As a result, thermal load and thermal stress has little effect on the engine exhaust manifold. However, the result of modal analysis indicates that the structure vibration is excessive which may cause the structural cracking.

Numerical Simulation for Exhaust Manifold Based on the Serial Coupling of STAR-CCM+ and ABAQUS

This study aims to realize the serial coupling of STAR-CCM+6.04 and ABAQUS 6.11-1 and provide boundary conditions for the thermal fatigue analysis. To predict the thermal fatigue life of the internal combustion engine exhaust manifold effectively, the transient heat-transfer process between exhaust gases and exhaust manifolds should be reflected accurately. The transient fluid-solid-thermal coupling simulation on the exhaust manifold is carried out by using serial coupling method. The research of dealing with the problems of transient temperature loading, the mesh generating and the interface temperature interpolation of fluid and solid are conducted in the process of numerical simulation. The goal of bidirectional fluid and solid coupling simulation between the CFD software STAR-CCM+ and the FEA software ABAQUS is achieved and the transient temperature and thermal stress distribution are obtained. Comparison with the steady analysis results shows that it's a necessary and effective way of conducting transient analysis.

LES of the Exhaust Flow in a Heavy-Duty Engine

The flow in the exhaust port and the exhaust manifold of a heavy-duty Diesel engine has been studied using the Large Eddy Simulation approach. Some of the flow characteristics in these components a ...

873~1173 K에서 열처리된 강화흑연강(Compacted Graphite Iron, CGI)의 음향방출 특성

CGI는 주철보다 큰 강도 또는 작은 무게가 요구되는 응용에서 인기를 얻고 있다. 최근, 강화흑연강은 디젤 엔진 블록, 터보 하우징 및 배기 매니폴드에 사용된다. 이 논문은 873~1173 K에서 1~24 시간 동안 열화된 CGI340의 기계적 성질의 변화에 따른 음향방출 특성을 평가하였다. 연필심 파괴시험 결과에서, 탁월주파수 및 모재의 속도는 각각 97 kHz와 5,490 m/s이었다. 인장시험에서 모재는 상대적으로 높은 탁월주파수를 얻었다. 그러나 열처리된 재료, 열처리 시간이 길고, 열처리 온도가 높을수록, 낮은 주파수의 영역에서 얻어졌다. 이러한 현상은 장기간의 사용에 의해 나타난다. CGI is gaining popularity in applications that require either greater strength, or lower weight than cast iron. Recently, compacted graphite iron has been used for diesel engine blocks, turbo housings and exhaust manifolds. This paper were assessed acoustic emission characteristics according to the mechanical properties change of degraded CGI340 during 1-24 hours at 873~1173 K. In results of pencil lead fracture test, the dominant frequency and the velocity of base metal were 97 kHz and 5490 m/sec, respectively. The base metal in a tensile test was obtained relatively high dominant frequency. However, the heat treated materials, the longer the heat treatment time, the higher the heat treatment temperature, were obtained in the area of lower frequencies. This phenomenon appears by long-term use.

873~1273 K에서 열화된 강화흑연강의 기계적 특성 연구

벌레 모양 흑연철로 알려진 강화흑연강(CGI)은 주철보다 더 강하고 더 가벼운 것이 요구되는 응용제품에서 인기를 얻고 있는 금속이다. 최근 강화흑연강 디젤엔진 블록에 사용되고 있다. 본 연구에서는 디젤엔진의 배기 매니폴드에 사용되는 것을 고려하여, 873~1273 K에서 1~96 시간 열처리를 실시하여 CGI340의 기계적 특성을 평가하였다. 열처리를 실시한 시험편의 인장강도는 모재에 비하여 전체적으로 낮은 인장강도를 나타내었다. 열처리 시간이 증가할수록 인장강도가 감소하였으며, 열처리 온도가 높고 시간이 길어질수록 더 많이 감소하였다. 초음파 피로시험에 의한 피로한도는 모재는 약 130 MPa, 1173 K(96 hrs) 시험편은 약 100 MPa을 나타내었다. 경도는 열처리 시간이 증가할수록 감소하였으며, 열처리 온도가 높을수록 경도의 분포가 낮아졌다. 그리고 CGI340에 분포하는 구상흑연의 평균경도는 120 Hv, 벌레 모양 흑연의 평균경도는 114 Hv로 기지조직인 페라이트보다 낮은 경도를 나타내었다. 열처리 온도 및 시간에 따라서 구상흑연 및 벌레 모양 흑연에 대한 변화는 일정하지 않지만, 열처리 시간이 길어짐에 따라 기지조직의 결정립이 커지는 것을 확인하였다. Compacted graphite iron(CGI), also known as vermicular graphite iron, is a metal which is gaining popularity in applications that require either greater strength, or lower weight than cast iron. Recently compacted graphite iron has been used for diesel engine blocks. Considering that using in exhaust manifold of the diesel engine, CGI340 was conducted the heat treatment during 1 hour to 96 hours from 873 to 1273 K. Mechanical characteristics were evaluated. The obtained results are as follows; The tensile strength of the heat treated specimens showed overall lower tensile strength than that of the base metal. Tensile strength decreases with increasing of heat treatment time, and the higher heat treatment temperature and the longer time, were more reduced. The fatigue limit by the ultrasonic fatigue test was approximately 130 MPa of base metal, 100 MPa of 1173 K (96 hrs) specimen, respectively. The hardness decreases with increasing heat treatment time, and the higher the heat treatment temperature was lowered hardness distribution. In CGI340, average hardness of nodular graphite was 120 Hv, average hardness of vermicular graphite was 114 Hv. This showed lower hardness than the base structure ferrite. The nodular graphite and vermicular graphite according to the heat treatment temperature and time didn't have a consistent change. However, the grain size of base structure grew with increasing of heat treatment time.

엔진 배기열 이용 유기랭킨사이클에 대한 실험적 연구

본 연구에서는 산업용 가스 엔진의 배기 폐열을 회수하여 발전하는 유기랭킨사이클을 구성하고 시스템 성능 분석 실험을 수행하였다. 엔진 배기가스 열을 작동유체(냉매 R134a)에 흡수시키기 위해 Shell & Tube 방식 열교환기를 엔진 배기 매니폴드 후단에 장착하였다. 엔진출력 60 kW인 조건에서 약 63 kW의 배기가스 열을 배출하였으며, 열교환기를 통해 작동유체에 흡수된 열량은 43~46 kW로서 배기가스 열회수율은 68~73%, 최대출력은 4.6 kW로서 배기가스 열량에 대한 최대출력의 비는 7.3%을 나타내었다. In this study, an organic Rankine cycle(ORC) for gas engine waste heat recovery for industry has been constructed and a performance analysis test has been carried out. Shell & tube style heat exchanger has been equipped on an engine exhaust manifold in order to absorb heat of engine exhaust gas into the working fluid(refrigerant R134a). Under 60 kW of engine power output, about 63 kW of engine exhaust gas heat was discharged and the proportion of heat recovered was 68~73% while 43~46 kW of heat was absorbed into working fluid. Consequently rated power output of ORC was 4.6 kW while the ratio of rated power output to engine exhaust gas heat was 7.3%.

Continuum damage mechanics application in low-cycle thermal fatigue

In this article, a fatigue model for low-cycle thermal fatigue formulated in a continuum damage mechanics framework is presented. The model is based on a unified damage law presented by Lemaitre for low-cycle fatigue, which has been extended to low-cycle thermal fatigue. The temperature dependencies of material parameters are considered in the damage evolution integration to take the non-isothermal condition of loading into account. This model considers the stress triaxiality and non-linearity of damage evolution, and it is developed to a fatigue damage accumulation rule in which the load sequence effect is also included. The stabilized structural response under thermomechanical loading motivates the use of uncoupled analysis approach making the model a fast tool suitable for design purposes in the costly and time-consuming field of thermomechanical fatigue life assessment. To demonstrate the capability and ease of use of this model for real industrial applications, the low-cycle thermal fatigue life of a stainless steel engine exhaust manifold which is in an early stage of design is assessed.

Flow Field Analysis of Pulse Converter Exhaust Manifold of Diesel Engines

A three-dimensional unsteady flow for the pulse converter exhaust manifold of 8-cylinder diesel engine was numerical simulated to get the flow characteristics of the exhaust manifold. Simulation results show that there are strong eddy flows, low pressure closed recirculation flow region in the exhaust manifold. Afterwards the structure optimization of the exhaust manifold with baffle was put forward and then the unsteady flow in the normal exhaust manifold, the exhaust manifold with baffle of 30 degrees and the exhaust manifold of 15 degrees were simulated and analyzed. It is concluded that the exhaust manifold with baffle is better than that without baffle, the recirculation flow region and the pressure loss in the exhaust manifold with baffle of 30 degrees is smaller than in it with baffle of 15 degree and the flow in the former exhaust manifold is much smoother.

Lifetime Prediction of Thermo-Mechanical Fatigue for Exhaust Manifold

In this research, the non-linear thermo-mechanical simulation, experimental study and lifetime prediction of engine exhaust manifold were systematically analyzed. Fluid-structure coupled method was employed in the simulation. Heat transfer analysis simultaneous considered radiation, convection and conduction. Inelastic properties of the materials used for the thermo-mechanical analysis included kinematic hardening and creep. Some models were introduced and used to predict lifetime of the manifold. Temperature data obtained during the engine bench tests can be accurately matched with the analysis results. The results indicated that the highest temperature located on the confluence of exhaust manifold and the plastic dissipated energy field caused by the cyclic thermal loading can be matched with the crack zone of exhaust manifold.