Effects of Tumble and Swirl Flows on the Turbulence Scale Near the TDC in a 4-Valve S.I. Engine

2001 ◽  
Author(s):  
Ki Hyung Lee ◽  
Chang Sik Lee ◽  
Hyun Jong Park ◽  
Dae Sik Kim
Keyword(s):  
Flow Field ◽  
Propagation Speed ◽  
Turbulence Scale ◽  
Iccd Camera ◽  
Spark Plug ◽  
Swirl Flows ◽  
Intake Stroke ◽  
Initial Flame ◽  
Cylinder Flow ◽  
Intake Flow

Abstract It has known that the in-cylinder flow field has a significant effect on the engine combustion. Especially, the turbulence scale at the ignition toning plays an important role in enhancing propagation speed of initial flame. Thus, in this study, various flow fields such as tumble and swirl flows were generated by intake flow control valves. The effects of tumble and swirl flows on the turbulence scale were experimentally investigated in a 4-valve S.I. engine. For the investigation of the flow field, the single frame PTV and the two color PIV techniques were developed to clarify in-cylinder flow pattern during intake stroke and turbulence intensity near the spark plug during compression stroke, respectively. The flame propagation was visualized by an ICCD camera and its images were analyzed to compare the flow field.

Effects of tumble and swirl flows on turbulence scale near top dead centre in a four-valve spark ignition engine

2003 ◽  
Vol 217 (7) ◽  
pp. 607-615 ◽  
Author(s):  
K H Lee ◽  
C S Lee
Keyword(s):  
Flame Propagation ◽  
Propagation Speed ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Turbulence Scale ◽  
Iccd Camera ◽  
Spark Plug ◽  
Swirl Flows ◽  
Initial Flame ◽  
Dead Centre

The in-cylinder flowfield and the turbulence scale at the ignition timing play an important role in enhancing the propagation speed of the initial flame and the engine combustion. The aim of this work is to investigate the effect of tumble and swirl flows on the turbulence scale near the top dead centre in a four-valve spark ignition (SI) engine by an experimental method. In this study, various flowfields such as tumble and swirl flows were generated by intake flow control valves. For investigation of the flowfields, the single-frame particle tracking velocimeter (PTV) and the twocolour particle image velocimeter (PIV) techniques were developed to clarify the in-cylinder flow pattern during the intake stroke and the turbulence intensity near the spark plug during the compression stroke respectively. In addition, the flame propagation was visualized by an ICCD camera, and its images were analysed to compare the flowfields. From these experimental results, the effects of tumble and swirl flows on the turbulence scale and the flame propagation speed were clarified.

scholarly journals The Relationship between In-Cylinder Flow-Field near Spark Plug Areas, the Spark Behavior, and the Combustion Performance inside an Optical S.I. Engine

2019 ◽  
Vol 9 (8) ◽  
pp. 1545 ◽  
Author(s):  
Atsushi Nishiyama ◽  
Minh Khoi Le ◽  
Takashi Furui ◽  
Yuji Ikeda
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Entire Area ◽  
Combustion Performance ◽  
Simultaneous Imaging ◽  
Spark Plug ◽  
Combustion Duration ◽  
Image Velocimetry ◽  
Flame Development ◽  
Cylinder Flow

The stringent regulations that were placed on gasoline vehicles demand significant improvement of the powertrain unit, not only to become cleaner but also more efficient. Therefore, there is a strong need to understand the complex in-cylinder processes that will have a direct effect on the combustion quality. This study applied multiple high-speed optical imaging to investigate the interaction between the in-cylinder flow, the spark, the flame, and combustion performance. These individual elements have been studied closely in the literature but the combined effect is not well understood. Simultaneous imaging of in-cylinder flow and flame tomography using high-speed Particle Image Velocimetry (PIV), as well as simultaneous high-speed spark imaging, were applied to port-injected optical gasoline imaging. The captured images were processed using in-house MATLAB algorithms and the deduced data shows a trend that higher in-cylinder flow velocity near the spark will increase the stretch distance of the spark and decrease the ignition delay. However, these do not have much effect on the combustion duration, and it is the flow-field in the entire area surrounding the flame development that will influence how fast the combustion and flame growth will occur.

scholarly journals Optical Investigation of a Partial Fuel Stratification Strategy to Stabilize Overall Lean Operation of a DISI Engine Fueled with Gasoline and E30

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 396
Author(s):  
Cinzia Tornatore ◽  
Magnus Sjöberg
Keyword(s):  
Volume Fraction ◽  
Direct Injection ◽  
Combustion Process ◽  
Pilot Injection ◽  
Optical Investigation ◽  
Flame Kernel ◽  
Lean Combustion ◽  
Fuel Stratification ◽  
Spark Plug ◽  
Initial Flame

This paper offers new insights into a partial fuel stratification (PFS) combustion strategy that has proven to be effective at stabilizing overall lean combustion in direct injection spark ignition engines. To this aim, high spatial and temporal resolution optical diagnostics were applied in an optically accessible engine working in PFS mode for two fuels and two different durations of pilot injection at the time of spark: 210 µs and 330 µs for E30 (gasoline blended with ethanol by 30% volume fraction) and gasoline, respectively. In both conditions, early injections during the intake stroke were used to generate a well-mixed lean background. The results were compared to rich, stoichiometric and lean well-mixed combustion with different spark timings. In the PFS combustion process, it was possible to detect a non-spherical and highly wrinkled blue flame, coupled with yellow diffusive flames due to the combustion of rich zones near the spark plug. The initial flame spread for both PFS cases was faster compared to any of the well-mixed cases (lean, stoichiometric and rich), suggesting that the flame propagation for PFS is enhanced by both enrichment and enhanced local turbulence caused by the pilot injection. Different spray evolutions for the two pilot injection durations were found to strongly influence the flame kernel inception and propagation. PFS with pilot durations of 210 µs and 330 µs showed some differences in terms of shapes of the flame front and in terms of extension of diffusive flames. Yet, both cases were highly repeatable.

Visualization of Different Flashback Mechanisms for H2/CH4 Mixtures in a Variable-Swirl Burner

2014 ◽  
Author(s):  
Parisa Sayad ◽  
Alessandro Schönborn ◽  
Mao Li ◽  
Jens Klingmann
Keyword(s):  
Flow Field ◽  
Mass Flow ◽  
High Speed ◽  
Vortex Breakdown ◽  
Propagation Speed ◽  
Swirl Burner ◽  
Air Mass ◽  
Spatial Propagation ◽  
Fuel Mixtures ◽  
Flame Flashback

Flame flashback from the combustion chamber to the premixing section is a major operability issue when using high H2 content fuels in lean premixed combustors. Depending on the flow-field in the combustor, flashback can be triggered by different mechanisms. In this work, three flashback mechanisms of H2/CH4 mixtures were visualized in an atmospheric variable swirl burner using high speed OH* chemiluminescence imaging. The H2 mole fraction of the tested fuel mixtures varied between 0.1 and 0.9. The flow-field in the combustor was varied by changing the swirl number from 0.0 to 0.66 and the total air mass-flow rate from 75 to 200 SLPM (standard liters per minute). The following three types of flashback mechanism were observed: Flashback caused by combustion induced vortex breakdown occurred at swirl numbers ≥ 0.53 for all of the tested fuel mixtures. Flashback in the boundary layer and flashback due to autoignition were observed at low swirl numbers and low total air mass-flow rates. The temporal and spatial propagation of the flame in the optical section of the premixing tube during flashback was studied and flashback speed for different mechanisms was estimated. The flame propagation speed during flashback was significantly different for the different mechanisms.

Numerical Analysis of Swirl Control Strategies in a Four Valve HSDI Diesel Engine

2004 ◽  
Author(s):  
S. Fontanesi ◽  
E. Mattarelli ◽  
L. Montorsi
Keyword(s):  
Flow Field ◽  
Control Strategies ◽  
Cfd Simulations ◽  
Full Load ◽  
Partial Load ◽  
Swirl Intensity ◽  
Port Design ◽  
Current Production ◽  
Hsdi Diesel Engine ◽  
Cylinder Flow

Recent four value HSDI Diesel engines are able to control the swirl intensity, in order to enhance the in-cylinder flow field at partial load without decreasing breathing capabilities at full load. Making reference to a current production engine, the purpose of this paper is to envestiage the influence of port design and flow-control strategies on both engine permeability and in-cylinder flow field. Using previously validated models, 3-D CFD simulations of the intake and compression strokes are performed in order to predict the in-cylinder flow patterns originated by the different configurations. The comparison between the two configurations in terms of airflow at full load indicates that Geometry 2 can trap 3.03% more air than Geometry 1, while the swirl intensity at IVC is reduced (−30%). The closure of one intake valve (the left one) is very effective to enhance the swirl intensity at partial load: the Swirl Ratio at IVC passes from 0.7 to 2.6 for Geometry 1, while for Geometry 2 it varies from 0.4 to 2.9.

Numerical Comparative Analysis of In-Cylinder Tumble Flow Structures in Small PFI Engines Equipped by Heads Having Different Shapes and Squish Areas

2012 ◽  
Author(s):  
Stefania Falfari ◽  
Gian Marco Bianchi ◽  
Luca Nuti
Keyword(s):  
Flow Structure ◽  
Mutual Influence ◽  
Ignition Time ◽  
Three Dimensional ◽  
Valve Lift ◽  
Spark Plug ◽  
Piston Valve ◽  
Cylinder Flow ◽  
Roof Angle ◽  
Motorcycle Engine

For increasing the thermal engine efficiency, faster combustion and low cycle-to-cycle variation are required. In PFI engines the organization of in-cylinder flow structure is thus mandatory for achieving increased efficiency. In particular the formation of a coherent tumble vortex with dimensions comparable to engine stroke largely promotes proper turbulence production extending the engine tolerance to dilute/lean mixture. For motorbike and scooter applications, tumble has been considered as an effective way to further improve combustion system efficiency and to achieve emission reduction since layout and weight constraints limit the adoption of more advanced concepts. In literature chamber geometry was found to have a significant influence on bulk motion and turbulence levels at ignition time, while intake system influences mainly the formation of tumble vortices during suction phase. The most common engine parameters believed to affect in-cylinder flow structure are: 1. Intake duct angle; 2. Inlet valve shape and lift; 3. Piston shape; 4. Pent-roof angle. The present paper deals with the computational analysis of three different head shapes equipping a scooter/motorcycle engine and their influence on the tumble flow formation and breakdown, up to the final turbulent kinetic energy distribution at spark plug. The engine in analysis is a 3-valves pent-roof motorcycle engine. The three dimensional CFD simulations were run at 6500 rpm with AVL FIRE code on the three engines characterised by the same piston, valve lift, pent-roof angle and compression ratio. They differ only in head shape and squish areas. The aim of the present paper is to demonstrate the influence of different head shapes on in-cylinder flow motion, with particular care to tumble motion and turbulence level at ignition time. Moreover, an analysis of the mutual influence between tumble motion and squish motion was carried out in order to assess the role of both these motions in promoting a proper level of turbulence at ignition time close to spark plug in small 3-valves engines.

scholarly journals Effect of Engine Specifications on In-Cylinder Flow Field in a Spark-Ignited Natural Gas Engine

1999 ◽  
Vol 34 (11) ◽  
pp. 764-773
Author(s):  
Yukiyoshi Fukano ◽  
Kazuo Tachibana ◽  
Shigeo Kida ◽  
Toshikazu Kadota
Keyword(s):  
Natural Gas ◽  
Flow Field ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Cylinder Flow
Sign in / Sign up

Export Citation Format

Share Document