Correlation of the Combustion Characteristics of Spark Ignition Engines With the In-Cylinder Flow Field Characterised Using PIV in a Water Analogy Rig

Numerical and experimental techniques were applied in order to study the in-cylinder flow field in a commercial four-valve per cylinder spark ignition engine. Investigation was aimed at analyzing the generation and evolution of tumble-vortex structures during the intake and compression strokes, and the capacity of this engine to promote turbulence enhancement during tumble degradation at the end of the compression stroke. For these purposes, three different approaches were analyzed. First, steady flow rig tests were experimentally carried out, and then reproduced by computational fluid dynamics (CFD). Once CFD was assessed, cold dynamic simulations of the full engine cycle were performed for several engine speeds (1500 rpm, 3000 rpm, and 4500 rpm). Steady and cold dynamic results were compared in order to assess the feasibility of the former to quantify the in-cylinder flow. After that, combustion was incorporated by means of a homogeneous heat source, and dynamic boundary conditions were introduced in order to approach real engine conditions. The combustion model estimates the burning rate as a function of some averaged in-cylinder flow variables (temperature, pressure, turbulent intensity, and piston position). Results were employed to characterize the in-cylinder flow field of the engine and to establish similarities and differences between the three performed tests that are currently used to estimate the engine mean flow characteristics (steady flow rig, and cold and real dynamic simulations).

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Two-Dimensional In-Cylinder Flow Field in a Natural Gas Fueled Spark Ignition Engine Probed by Particle Tracking Velocimetry and Its Dependence on Engine Specifications

10.4271/1999-01-1534 ◽

1999 ◽

Author(s):

Yukiyoshi Fukano ◽

Haruo Hisaki ◽

Shigeo Kida ◽

Toshikazu Kadota

Keyword(s):

Natural Gas ◽

Flow Field ◽

Particle Tracking ◽

Particle Tracking Velocimetry ◽

Spark Ignition ◽

Spark Ignition Engine ◽

Two Dimensional ◽

Gas Fueled ◽

Cylinder Flow

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Assessment of Combustion Characteristics of Higher Alcohols in a Direct Injection Spark Ignition Engine

Volume 2: Fuels; Numerical Simulation; Engine Design, Lubrication, and Applications ◽

10.1115/icef2013-19180 ◽

2013 ◽

Cited By ~ 1

Author(s):

Kristina Lawyer ◽

Thomas Wallner ◽

Andrew Ickes ◽

Scott Miers ◽

Jeffrey Naber ◽

...

Keyword(s):

Alternative Fuels ◽

Direct Injection ◽

Carbon Number ◽

Substantial Reduction ◽

Spark Ignition ◽

Combustion Characteristics ◽

Spark Ignition Engine ◽

Spark Ignition Engines ◽

Combustion Properties ◽

Direct Injection Spark Ignition

The U.S. Renewable Fuel Standard requires an increase in the production of ethanol and advanced biofuels up to 36 billion gallons by 2022. Ethanol will be limited to 15 billion gallons, which leaves 21 billion gallons to come from other sources. Due to its high octane number, renewable character, and minimal toxicity, ethanol was believed to be one of the most favorable alternative fuels to displace gasoline in spark ignition engines. Replacing gasoline with ethanol results in a substantial reduction in vehicle range, and high ethanol content blends can cause material compatibility issues and require adaptive engine calibrations. In addition, ethanol is fully miscible in water which requires blending at distribution sites instead of the refinery. Higher carbon number alcohols, on the other hand, have a higher energy density and lower affinity for water than ethanol, which could mitigate some of the above mentioned issues. However, little information is available on the combustion characteristics of a majority of the longer-chain alcohols. This study evaluates the combustion properties of higher carbon number alcohols, ranging from ethanol (C2) to hexanol (C6) in a direct-injection, spark-ignition engine. Test fuels are created by splash blending alcohols at a volumetric concentration of 50% with a blendstock for oxygenate blending. Combustion characteristics are evaluated by comparing overall efficiencies as well as heat release characteristics and emissions for a set of representative steady-state operating points. Results suggest that combustion properties of blends of alcohols with carbon numbers from two to six are similar to those of the reference fuel at low and medium engine loads. Properties of blends of alcohols with carbon numbers from two to four are similar to those of the reference fuel even at high loads. However, due to their reduced knock resistance, the suitability of longer chain alcohols, specifically C5 and longer, as blending agents at increased levels is questionable.

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Effect of spark ignition location on the turbulent jet ignition characteristics in a lean burning natural gas engine

International Journal of Engine Research ◽

10.1177/14680874211064677 ◽

2022 ◽

pp. 146808742110646

Author(s):

Xue Yang ◽

Yong Cheng ◽

Qingwu Zhao ◽

Pengcheng Wang ◽

Jinbing Chen

Keyword(s):

Natural Gas ◽

Flow Field ◽

Flame Propagation ◽

Combustion Rate ◽

Propagation Distance ◽

Spark Ignition ◽

Turbulent Jet ◽

Gas Engine ◽

Natural Gas Engine ◽

Cylinder Flow

The Turbulent Jet Ignition is an effective concept to achieve stable lean burning for natural gas engines due to the multiple ignition sources, high ignition energy, and fast combustion rate. A variation of the ignition location has a non-negligible effect on the ignition performance of the TJI system. The present work aims to provide more details on this effect by numerical simulations. Both factors of the additional fuel supply to the pre-chamber and the in-cylinder flow field are taken into consideration in this study. A numerical model is built based on a lean burning natural gas engine and validated by experimental results. Five different spark ignition sources are equally arranged on the vertical axis of the pre-chamber, with different distances from the connecting orifices. Simulations are carried out under the same initial and boundary conditions except for the location of the ignition source. Combustion pressure, in-cylinder flow field, fuel mass fraction distribution, and heat release rate are analyzed to study the in-cylinder ignition and combustion process. The results show that a rotational flow and a non-uniform fuel distribution are formed in the pre-chamber during the compression stroke. The turbulent jet characteristics are significantly influenced by the coupling of two factors: the combustion rate inside the pre-chamber as well as the flame propagation distance from the ignition source to the connecting orifices. Rapid combustion rate and shorter flame propagation distance both lead to the earlier ejection of cold jets and hot jets. Among five ignition sources, the one located closest to the connecting orifices generates earlier hot jets with the highest mean velocity. The jets are more effective to ignite the lean mixture and could decrease the combustion duration of the main chamber.

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Parallel methodology to capture cyclic variability in motored engines

International Journal of Engine Research ◽

10.1177/1468087416662544 ◽

2016 ◽

Vol 18 (4) ◽

pp. 366-377 ◽

Cited By ~ 15

Author(s):

Muhsin M Ameen ◽

Xiaofeng Yang ◽

Tang-Wei Kuo ◽

Sibendu Som

Keyword(s):

Flow Field ◽

Time Scale ◽

Initial Pressure ◽

Computational Time ◽

Spark Ignition Engines ◽

Cyclic Variability ◽

Parallel Simulations ◽

Eddy Simulation ◽

Long Time ◽

Cylinder Flow

Numerical prediction of cycle-to-cycle variability in spark ignition engines is extremely challenging for two key reasons: (1) high-fidelity methods such as large eddy simulation are required to accurately capture the in-cylinder turbulent flow field and (2) cycle-to-cycle variability is experienced over long time scales, and hence, the simulations need to be performed for hundreds of consecutive cycles. In this study, a methodology is proposed to dissociate this long time-scale problem into several shorter time-scale problems, which can considerably reduce the computational time without sacrificing the fidelity of the simulations. The strategy is to perform multiple parallel simulations, each of which encompasses two to three cycles, by effectively perturbing the simulation parameters such as the initial and boundary conditions. The proposed methodology is validated for the prediction of cycle-to-cycle variability due to gas exchange in a motored transparent combustion chamber engine by comparing with particle image velocimetry measurements. It is shown that by perturbing the initial velocity field effectively based on the intensity of the in-cylinder turbulence, the mean and variance of the in-cylinder flow field are captured reasonably well. Adding perturbations in the initial pressure field and the boundary pressure improves the predictions. It is shown that this new approach is able to give accurate predictions of the flow field statistics in considerably less time than that required for the conventional approach of simulating consecutive engine cycles.

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