Direct Injection Diesel Engine Combustion Modeling (original) (raw)
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In this study the simulation process of non-premixed combustion in a direct injection single cylinder diesel engine has been described. Direct injection diesel engines are used both in heavy duty vehicles and light duty vehicles. The fuel is injected directly into the combustion chamber. The fuel mixes with the high pressure air in the combustion chamber and combustion occurs. Due to the non-premixed nature of the combustion occurring in such engines, non-premixed combustion model of ANSYS FLUENT 14.5 can be used to simulate the combustion process. A 4-stroke diesel engine corresponds to one fuel injector hole without considering valves was modeled and combustion simulation process was studied. Here two types of combustion chambers were compared. Combustion studies of both chambers:-shallow depth and hemispherical combustion chambers were carried out. Emission characteristics of both combustion chambers had also been carried out. The obtained results are compared. It has been found that hemispherical combustion chamber is more efficient as it produces higher pressure and temperature compared to that of shallow depth combustion chamber. As the temperature increases the formation of NO x emissions and soot formation also get increased.
Simulation of In-Cylinder Processes in a DI Diesel Engine with Various Injection Timings
2015
The gas motion inside the engine cylinder plays a very important role in determining the thermal efficiency of an internal combustion engine. A better understanding of in cylinder gas motion will be helpful in optimizing engine design parameters. An attempt has been made to study the combustion processes in a compression ignition engine and simulation was done using computational fluid dynamic (CFD) code FLUENT. An Axisymmetric turbulent combustion flow with heat transfer is to be modeled for a flat piston 4-stroke diesel engine. The unsteady compressible conservation equations for mass (Continuity), axial and radial momentum, energy, species concentration equations can express the flow field and combustion in axisymmetric engine cylinder. Turbulent flow modeling and combustion modeling was analyzed in formulating and developing a model for combustion process. 1.
2007
A two zone model for the calculation of the closed cycle of a compression ignition direct injection (DI) diesel engine is developed. This model divides the cylinder contents into a non-burning zone of air surrounding the fuel spray jets issuing from injector nozzle holes and another homogenous zone in which fuel is supplied continuously from injector and burned with entrained air from the air zone. The growth of the fuel spray zone in the combustion chamber, consisting of a number of fuel-air conical jets equal to the injector nozzle holes, is carefully modeled by incorporating jet mixing and main relevant spray parameters. Application of the mass, energy and state equations in each one of the two zones yields local temperature and cylinder pressure histories. Furthermore, compression stroke, heat transfer, ignition delay period, rate of combustion, pollutants formation and expansion stroke are considered in this thermodynamic modeling. For the calculation of the constituents in exh...
Modeling of Combustion and Carbon Oxides Formation in Direct Injection Diesel Engine
International Journal of Engineering, 2012
When looking at the effects of diesel engine exhaust on the environment, it is important to first look at the composition of the exhaust gases. Over 99.5% of the exhaust gases are a combination of nitrogen, oxygen, carbon dioxide, and water. With the exception of carbon dioxide, which contributes about 5% of the total volume, the diesel engine exhaust consists of elements which are part of the natural atmosphere and are not harmful to the environment. Carbon dioxide emissions are directly related to the efficiency of the combustion unit. The higher efficiency obtained with lower amount of CO2 emissions. In this study we are interested in the effects of exhaust gas recirculation (EGR) on combustion and emissions direct injection diesel engine. In particular, the effects of carbon dioxide (CO2), water (H2O), carbon monoxide (CO), some different quantities of EGR, analysed and quantified numerically. Other parameters tha affect the rate of oxides of carbon in the bowl shape, the Mexican hat and spherical geometry are analyzed in this work. Therefore, A modified version of the computational fluid dynamics (CFD) Code KIVA-3V has been used for modelling combustion process and engine emission, in particular carbon oxides emission and its control. Simulation was carried out by using a two-stroke single-cylinder direct injection diesel engine.
Computational Fluid Dynamics (CFD) study of compression ignition (CI) engines provides invaluable insights into in-cylinder conditions and processes, which greatly expands on the very limited detail provided by engine output measurements, fuel consumption measurements, and engine-out measurements of exhaust emissions. CFD modeling and simulation has therefore become an attractive alternative for engine analysis in place of full experimental testbed study in recent years. In this research work, the performance of a single cylinder four stroke diesel engine was investigated. Commercial simulation software ANSYS Forte was used to study the combustion and emission characteristics of a diesel engine, in order to establish strategies for improvement of in-cylinder combustion and emission control. Normal heptane (n-heptane) was used as the surrogate fuel to represent diesel. Simulation results are compared against data from experimental testbed studies in terms of in-cylinder pressure profiles, heat release rate and exhaust emission of oxides of nitrogen (NO x), soot and unburned hydrocarbon (UHC) levels. The pressure trace from the simulations is found to be within a reasonable error limit of 10%. The combustion process is simulated with special focus on exhaust emissions of soot, NO x and unburned hydrocarbon. Graphical plots for mass fraction of soot, NO x and UHC are presented and discussed to elucidate the formation of these emissions. Graphics contours of temperature, NO mass fraction and oxygen concentration within the combustion chamber are also presented and discussed. The effects of injection timing on engine in-cylinder pressure, heat release rate and exhaust emissions are also studied by varying the injection timing and maintaining constant injection duration. Results are compared for the three different injection timings investigated, namely start of injection (SOI) 18 o bTDC, 15 o bTDC and 12 o bTDC. Emissions of soot and NO x are found to decrease with retarded injection timing. However, the peak in-cylinder pressure is greatly reduced and hence the output power is low. Injection timing is found to have no significant effect on emissions of UHC. The optimum injection timing that gives high output power and relatively low emission is 15 o bTDC. Downloaded From: http://proceedings.asmedigitalcollection.asme.org/ on 08/31/2017 Terms of Use: http://www.asme.org/about-asme/terms-of-use
2018
Article history: Received 29 September 2018 Received in revised form 16 December 2018 Accepted 24 December 2018 Available online 28 December 2018 This study investigated the non-premixed combustion procedure by using ANSYS 18 software, with varied compression ratios as one of the effective engine design parameters and the theoretical cylinder pressure values were validated with the obtained result. Diesel and n-Heptane fuels were utilized to investigate their effects on combustion process. There are several combustion parameters such as, in-cylinder temperature, in-cylinder pressure, Heat Release rate (HRR), swirl ratio and tumble motion and all these parameters were compared for both the fuels. This work considered the compression ratios of 13, 15 and 17 to find out optimum value at which the combustion process was the best and attained stability. The obtained result reveals that with increasing compression ratio, the pressure and temperature within the cylinder were boosted up alo...
Flow Modeling in a DI Diesel Engine Combustion Chamber Using CFD
2016
Turbulent flow field in a four cylinder direct injection (DI) diesel engine combustion chamber has been simulated using computational fluid dynamics (CFD). A commercial CFD code, namely Fluent was used to model 3D flow field. Three different geometrical shapes of combustion chamber were considered in the flow analysis in order to clarify the effect of combustion chamber geometry on the flow field characteristics. The simulation results showed that the bowl shapes of the combustion chambers greatly influenced the pressure, velocity and temperature distributions at the end of the compression stroke. Therefore, it has been concluded that geometry of combustion chamber could be optimized using CFD
CFD modeling of the in-cylinder flow in Direct-injection Diesel engine
Internal combustion engines in now a days is the best available reliable source of power for all domestic, large scale industrial and transportation applications. The major issue arises at the efficiency of these engines. Every attempt made to improve these engines tends to attain the maximum efficiency. The performances of the diesel engines are enhanced by proper design of inlet manifold, exhaust manifold, combustion chamber, piston etc. The study is about the effect of piston configurations on in- cylinder flow. Here a single cylinder direct injection diesel engine is used for study. For obtaining swirl intensity helical-spiral combination inlet manifold is used. Increase in swirl intensity results in better mixing of fuel and air. Swirl Velocities in the charge can be substantially increased during compression by suitable design of the piston. In the present work, a study on the effect of different piston configuration on air motion and turbulence inside the cylinder of a Direct Injection (DI) diesel is carried out using Computational Fluid Dynamics (CFD) code Fluent 13. Three dimensional models of the manifolds, pistons and the cylinder is created in CATIA V5 and meshed using the pre-processor Hypermesh 10.0.
Investigating Diesel Engine Performance and Emissions Using CFD
Energy and Power Engineering, 2013
Fluid flow in an internal combustion engine presents one of the most challenging fluid dynamics problems to model. This is because the flow is associated with large density variations. So, a detailed understanding of the flow and combustion processes is required to improve performance and reduce emissions without compromising fuel economy. The simulation carried out in the present work to model DI diesel engine with bowl in piston for better understanding of the in cylinder gas motion with details of the combustion process that are essential in evaluating the effects of ingesting synthetic atmosphere on engine performance. This is needed for the course of developing a non-air recycle diesel with exhaust management system [1]. A simulation was carried out using computational fluid dynamics (CFD) code FLU-ENT. The turbulence and combustion processes are modeled with sufficient generality to include spray formation, delay period, chemical kinetics and on set of ignition. Results from the simulation compared well with that of experimental results. The model proved invaluable in obtaining details of the in cylinder flow patterns, combustion process and combustion species during the engine cycle. The results show that the model over predicting the maximum pressure peak by 6%, (p-θ), (p-v) diagrams for different engine loads are predicted. Also the study shows other engine parameters captured by the simulation such as engine emissions, fuel mass fraction, indicated gross work, ignition delay period and heat release rate.
CFD modeling of the in-cylinder flow in direct-injection Diesel engines
Computers & Fluids, 2004
Three-dimensional flow calculations of the intake and compression stroke of a four-valve direct-injection Diesel engine have been carried out with different combustion chambers. A limited number of validation calculations of the compression stroke were first performed in order to explore the limits of CFD representation of the in-cylinder flow. The calculated flow field in three different combustion chambers was compared with laser Doppler velocimetry measurements; the comparison shows that the three-dimensional model is reasonably accurate for crank-angles around top dead center (TDC). In general, it performs better for low swirl combustion chambers while turbulence velocities are under-predicted when squish effects are important.