Cold-Start Computational Fluid Dynamics Simulation of Spark-Ignition Direct-Injection Engine

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Xiaofeng Yang ◽  
Tang-Wei Kuo ◽  
Kulwinder Singh ◽  
Rafat Hattar ◽  
Yangbing Zeng
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Engine Speed ◽  
Direct Injection ◽  
Cold Start ◽  
Spark Ignition ◽  
Dynamics Simulation ◽  
Residual Fraction ◽  
Direct Injection Engine ◽  
Start Process

Reliably starting the engine during extremely cold ambient temperatures is one of the largest calibration and emissions challenges in engine development. Although cold-start conditions comprise only a small portion of an engine's typical drive cycle, large amounts of hydrocarbon and particulate emissions are generated during this time, and the calibration of cold-start operation takes several months to complete. During the cold start period, results of previous cycle combustion event strongly influences the subsequent cycle due to variations in engine speed, residual fraction, residual wall film mass, in-cylinder charge and wall temperatures, and air flow distribution between cylinders. Including all these parameters in computational fluid dynamics (CFD) simulation is critical in understanding the cold start process in transient and cumulative manner. Measured cold start data of a production of four-cylinder spark-ignition (SI) direct-injection engine were collected for this study with an ambient temperature of −30 °C. Three-dimensional (3D) transient engine flow, spray, and combustion simulation over first three consecutive engine cycles is carried out to provide a better understanding of the cold-start process. Measured engine speed and one-dimensional (1D) conjugate heat transfer (CHT) model is used to capture realistic in-cylinder flow dynamics and transient wall temperatures for more accurate fuel–air mixing predictions. The CFD predicted cumulative heat release trend for the first three cycles matches the data from measured pressure analysis. The same observation can be made for the vaporized fuel mass as well. These observations are explained in the report.

Cold-Start CFD Simulation of Spark-Ignition Direct-Injection Engine

2017 ◽  
Author(s):  
Xiaofeng Yang ◽  
Tang-Wei Kuo ◽  
Kulwinder Singh ◽  
Rafat Hattar ◽  
Yangbing Zeng
Keyword(s):  
Engine Speed ◽  
Cfd Simulation ◽  
Direct Injection ◽  
Cold Start ◽  
Spark Ignition ◽  
Residual Fraction ◽  
Transfer Model ◽  
Particulate Emissions ◽  
Direct Injection Engine ◽  
Start Process

Reliably starting the engine during extremely cold ambient temperatures is one of the largest calibration and emissions challenges in engine development. Although cold-start conditions comprise only a small portion of an engine’s typical drive cycle, large amounts of hydrocarbon and particulate emissions are generated during this time, and the calibration of cold-start operation takes several months to complete. During the cold start period, results of previous cycle combustion event strongly influences the subsequent cycle due to variations in engine speed, residual fraction, residual wall film mass, in-cylinder charge and wall temperatures, and air flow distribution between cylinders. Include all these parameters in CFD simulation is critical in understanding the cold start process in transient and cumulative manner. Measured cold start data of a production four cylinder spark-ignition direct-injection engine was collected for this study with an ambient temperature of −30 °C. Three-dimensional transient engine flow, spray and combustion simulation over first 3 consecutive engine cycles is carried out to provide a better understandings of the cold-start process. Measured engine speed and 1D conjugate heat transfer model are used to capture realistic in-cylinder flow dynamics and transient wall temperatures for more accurate fuel-air mixing predictions. The CFD predicted cumulative heat release trend for the first 3 cycles matches the data from measured pressure analysis. The same observation can be made for the vaporized fuel mass as well. These observations are explained in the report.

Improving computational fluid dynamics modeling of Direct Injection Spark Ignition cold-start

2020 ◽  
pp. 146808742096398
Author(s):  
Arun C Ravindran ◽  
Sage L Kokjohn ◽  
Benjamin Petersen
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Flame Front ◽  
Turbulent Kinetic Energy ◽  
Direct Injection ◽  
Cold Start ◽  
Spark Ignition ◽  
Combustion Characteristics ◽  
Direct Injection Spark Ignition

Developing a profound understanding of the combustion characteristics of the cold-start phase of a Direct Injection Spark Ignition (DISI) engine is critical to meeting increasingly stringent emissions regulations. Computational Fluid Dynamics (CFD) modeling of gasoline DISI combustion under normal operating conditions has been discussed in detail using both the detailed chemistry approach and flamelet models (e.g. the G-Equation). However, there has been little discussion regarding the capability of the existing models to capture DISI combustion under cold-start conditions. Accurate predictions of cold-start behavior involves the efficient use of multiple models - spray modeling to capture the split injection strategies, models to capture the wall-film interactions, ignition modeling to capture the effects of retarded spark timings, combustion modeling to accurately capture the flame front propagation, and turbulence modeling to capture the effects of decaying turbulent kinetic energy. The retarded spark timing helps to generate high heat flux in the exhaust for the faster catalyst light-off during cold-start. However, the adverse effect is a reduced turbulent flame speed due to decaying turbulent kinetic energy. Accordingly, developing an understanding of the turbulence-chemistry interactions is imperative for accurate modeling of combustion under cold-start conditions. In the present work, combustion characteristics during the cold-start, fast-idle phase is modeled using the G-Equation flamelet model and the RANS turbulence model. The challenges associated with capturing the turbulent-chemistry interactions are explained by tracking the flame front travel along the Borghi-Peters regime diagram. In this study, a modified version of the G-Equation combustion model for capturing cold-start flame travel is presented.

Modeling laminar burning velocity of gasoline using an energy fraction-based mixing rule approach

2018 ◽  
Vol 233 (5) ◽  
pp. 1245-1258 ◽  
Author(s):  
Joohan Kim ◽  
Kyoungdoug Min
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Burning Velocity ◽  
Direct Injection ◽  
Velocity Model ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Mixing Rule ◽  
Laminar Burning Velocity ◽  
Direct Injection Spark Ignition

To determine an optimum combustion chamber design and engine operating strategies, computational fluid dynamics simulations of direct-injection spark-ignition engines have become an indispensable step in the powertrain development process. The laminar burning velocity of gasoline is known as an essential input parameter for combustion simulations. In this study, a new methodology for modeling the laminar burning velocity of gasoline for direct-injection spark-ignition engine simulations is proposed. Considering the gasoline as a complex mixture of hydrocarbon fuel, three hydrocarbons, iso-octane, n-heptane, and toluene were incorporated as surrogate fuel components to represent gasoline with distinct aromatic laminar flame characteristics compared to alkane. A mixing rule, based on energy fractions, was adopted to consider the compositional variation of gasoline. The laminar burning velocities of iso-octane, n-heptane, and toluene were calculated under wide thermo-chemical conditions in conjunction with detailed chemical reaction kinetics in the premixed flame simulation. Finally, a set of laminar burning velocity model equations was derived by curve-fitting the flame simulation results of each hydrocarbon component in consideration of the effect of temperature, pressure, and diluent. The laminar burning velocity model was validated against the measurement data of gasoline’s laminar burning velocity found in the literature, and was applied to the computational fluid dynamics simulation of a direct-injection spark-ignition engine under the various operating conditions to explore the prediction capability.

Large-eddy simulation of the flow in a direct injection spark ignition engine using an open-source framework

2020 ◽  
pp. 146808742090362
Author(s):  
Mateus Dias Ribeiro ◽  
Alex Mendonça Bimbato ◽  
Maurício Araújo Zanardi ◽  
José Antônio Perrella Balestieri ◽  
David P Schmidt
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Large Eddy Simulation ◽  
Open Source ◽  
Direct Injection ◽  
Spark Ignition ◽  
Spark Ignition Engines ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Direct Injection Spark Ignition

Direct injection spark ignition engines aim at reducing specific fuel consumption and achieving the strict emission standards in state of the art internal combustion engines. This can be achieved by research comprising experimental methods, which are normally expensive and limited, and computational fluid dynamics methods, which are often more affordable and less restricted than their experimental counterpart. In the latter approach, the costs are mainly related to the acquisition, usage, and maintenance of computational resources, and the license cost when commercial computational fluid dynamics codes are used. Therefore, in order to make the research of direct injection spark ignition engines and their internal processes more accessible, this article proposes a novel open-source and free framework based on the OpenFOAM computational fluid dynamics library for the simulation of the internal flow in direct injection spark ignition engines using a large-eddy simulation closure for modeling the turbulence within the gas phase. Finally, this framework is tested by simulating the Darmstadt engine in motored operation, validating the results with experimental data compiled by the Darmstadt Engine Workshop.

Sign in / Sign up

Export Citation Format

Share Document