Influence of flash boiling spray on the combustion characteristics of a spark-ignition direct-injection optical engine under cold start

2018 ◽  
Vol 188 ◽  
pp. 66-76 ◽  
Author(s):  
Jie Yang ◽  
Xue Dong ◽  
Qiang Wu ◽  
Min Xu
Keyword(s):  
Direct Injection ◽  
Cold Start ◽  
Spark Ignition ◽  
Combustion Characteristics ◽  
Optical Engine ◽  
Flash Boiling

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.

Flame Emission Characteristics in a Direct Injection Spark Ignition Optical Engine Using Image Processing Based Diagnostics

2018 ◽  
Author(s):  
Zhe Sun ◽  
Zhen Ma ◽  
Xuesong Li ◽  
Min Xu
Keyword(s):  
Image Processing ◽  
Diffusion Flame ◽  
Internal Combustion Engines ◽  
Imaging System ◽  
Direct Injection ◽  
Spark Ignition ◽  
Spectral Correlation ◽  
Optical Engine ◽  
Flame Emission ◽  
Direct Injection Spark Ignition

Non-intrusive measurements are always desirable in flame research, particularly in the study of internal combustion engines where intrusive measurements are usually not applicable. With the use of digital image processing and color analysis, the imaging system can be turned into an abstract multi-spectral system to determine the characteristics of flame emission. First this study conducts a precise calibration to make up a spectral correlation between the camera spectrum responses and the radical emissions of an ethanol diffusion flame. The color model of HSV is used to represent the camera spectrum responses. The actual wavelength of each radical of the diffusion flame has also been examined using a spectrograph. Subsequent experiment is the application of the spectral correlation into a direct injection spark ignition optical engine to research the combustion behavior. Two fuel injectors, different in nozzle configuration, were utilized and tested individually. The high-speed imaging system films hundreds of engine combustion cycles, and each cycle covers the propagation from the flame ignition stage towards the end of combustion. In those cycles, the presence of radicals of interest was captured and represented by Hue degree.

AN APPROACH TO MODELING FLASH-BOILING FUEL SPRAYS FOR DIRECT-INJECTION SPARK-IGNITION ENGINES

2016 ◽  
Vol 26 (12) ◽  
pp. 1197-1239 ◽  
Author(s):  
Christopher Price ◽  
Arash Hamzehloo ◽  
Pavlos Aleiferis ◽  
David Richardson
Keyword(s):  
Direct Injection ◽  
Spark Ignition ◽  
Spark Ignition Engines ◽  
Fuel Sprays ◽  
Flash Boiling ◽  
Direct Injection Spark Ignition

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.

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