403 Numerical Simulation of Combustion Process in Hythane Direct Injection Two-stroke Engine

The research on two-stroke engines has been focused lately on the development of direct injection systems for reducing the emissions of hydrocarbons by minimizing the fuel short-circuiting. Low temperature combustion (LTC) may be the next step to further improve emissions and fuel consumption; however, LTC requires unconventional ignition systems. Jet ignition, i.e., the use of prechambers to accelerate the combustion process, turned out to be an effective way to perform LTC. The present work aims at proving the feasibility of adopting passive prechambers in a high-pressure, direct injection, two-stroke engine through non-reactive computational fluid dynamics analyses. The goal of the analysis is the evaluation of the prechamber performance in terms of both scavenging efficiency of burnt gases and fuel/air mixture formation inside the prechamber volume itself, in order to guarantee the mixture ignitability. Two prechamber geometries, featuring different aspect ratios and orifice numbers, were investigated. The analyses were replicated for two different locations of the injection and for three operating conditions of the engine in terms of revolution speed and load. Upon examination of the results, the effectiveness of both prechambers was found to be strongly dependent on the injection setup.

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629 Numerical Simulation of Combustion Process in a Two-stroke Engine

The Proceedings of Yamanashi District Conference ◽

10.1299/jsmeyamanashi.2000.201 ◽

2000 ◽

Vol 2000 (0) ◽

pp. 201-202

Author(s):

Yasunori KOBAYASHI ◽

Kazuo SATO ◽

Masamitsu NAKANO

Keyword(s):

Numerical Simulation ◽

Combustion Process ◽

Stroke Engine

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Numerical Simulation on Effect of Nozzle-Hole Layout on Spray Characteristics and Combustion in a DI Diesel Engine

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.476-478.448 ◽

2012 ◽

Vol 476-478 ◽

pp. 448-452

Author(s):

Jun Zhang ◽

Chang Pu Zhao ◽

Nai Zhuan Chen ◽

Da Lu Dong ◽

Bo Zhong

Keyword(s):

Numerical Simulation ◽

Diesel Engine ◽

Direct Injection ◽

Combustion Process ◽

Three Dimensional ◽

Three Dimensional Model ◽

Spray Characteristics ◽

Fuel Atomization ◽

Di Diesel Engine ◽

Nozzle Hole

Diesel spray characteristics are closely related to the combustion of the engine where the spray tip penetration and the fuel atomization play a key role especially for direct injection (DI) diesel engine. With different nozzles, the fuel atomization and evaporation will be different thereby affecting the combustion and emission characteristics. A three-dimensional model is built based on the parameters of a DI diesel engine, and its validation is also validated. Three nozzle-hole layouts are designed in this research, including the conventional hole, multi-hole, and group-hole. The spray characteristics and combustion process are studied with three different nozzle-hole layouts by the way of numerical simulation. Further more, the effect of inter-hole spacing of group-hole nozzle on the evaporation rate and combustion process is researched here.

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

Energies ◽

10.3390/en14020396 ◽

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.

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Free Stream Behavior of Hydrogen Released from a Fluidic Oscillating Nozzle

Fluids ◽

10.3390/fluids6070245 ◽

2021 ◽

Vol 6 (7) ◽

pp. 245

Author(s):

Anja Fink ◽

Oliver Nett ◽

Simon Schmidt ◽

Oliver Krüger ◽

Thomas Ebert ◽

...

Keyword(s):

Free Stream ◽

Combustion Engine ◽

Direct Injection ◽

Combustion Process ◽

Vertical Direction ◽

Spray Angle ◽

Transport Sector ◽

Flow Measurements ◽

Injection Process ◽

Bottom Dead Center

The H2 internal combustion engine (ICE) is a key technology for complete decarbonization of the transport sector. To match or exceed the power density of conventional combustion engines, H2 direct injection (DI) is essential. Therefore, new injector concepts that meet the requirements of a H2 operation have to be developed. The macroscopic free stream behavior of H2 released from an innovative fluidic oscillating nozzle is investigated and compared with that of a conventional multi-hole nozzle. This work consists of H2 flow measurements and injection tests in a constant volume chamber using the Schlieren method and is accompanied by a LES simulation. The results show that an oscillating H2 free stream has a higher penetration velocity than the individual jets of a multi-hole nozzle. This behavior can be used to inject H2 far into the combustion chamber in the vertical direction while the piston is still near bottom dead center. As soon as the oscillation of the H2 free stream starts, the spray angle increases and therefore H2 is also distributed in the horizontal direction. In this phase of the injection process, spray angles comparable to those of a multi-hole nozzle are achieved. This behavior has a positive effect on H2 homogenization, which is desirable for the combustion process.

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The Effect of RME-1-Butanol Blends on Combustion, Performance and Emission of a Direct Injection Diesel Engine

Energies ◽

10.3390/en14102941 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2941

Author(s):

Wojciech Tutak ◽

Arkadiusz Jamrozik ◽

Karol Grab-Rogaliński

Keyword(s):

Diesel Engine ◽

Heat Release ◽

Direct Injection ◽

Specific Energy Consumption ◽

Combustion Process ◽

Constant Load ◽

Combustion Stability ◽

Performance And Emission ◽

Energy Share ◽

The Stability

The main objective of this study was assessment of the performance, emissions and combustion characteristics of a diesel engine using RME–1-butanol blends. In assessing the combustion process, great importance was placed on evaluating the stability of this process. Not only were the typical COVIMEP indicators assessed, but also the non-burnability of the characteristic combustion stages: ignition delay, time of 50% heat release and the end of combustion. The evaluation of the combustion process based on the analysis of heat release. The tests carried out on a 1-cylinder diesel engine operating at a constant load. Research and evaluation of the combustion process of a mixture of RME and 1-butanol carried out for the entire range of shares of both fuels up to 90% of 1-butanol energetic fraction. The participation of butanol in combustion process with RME increased the in-cylinder peak pressure and the heat release rate. With the increase in the share of butanol there was noted a decrease in specific energy consumption and an increase in engine efficiency. The share of butanol improved the combustion stability. There was also an increase in NOx emissions and decrease in CO and soot emissions. The engine can be power by blend up to 80% energy share of butanol.

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Combustion Thermodynamics of Ethanol, n-Heptane, and n-Butanol in a Rapid Compression Machine with a Dual Direct Injection (DDI) Supply System

Energies ◽

10.3390/en14092729 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2729

Author(s):

Ireneusz Pielecha ◽

Sławomir Wierzbicki ◽

Maciej Sidorowicz ◽

Dariusz Pietras

Keyword(s):

Heat Release ◽

Combustion Chamber ◽

Internal Combustion Engines ◽

Direct Injection ◽

Combustion Process ◽

Combustion Efficiency ◽

Injection System ◽

Rapid Compression Machine ◽

Process Indicators ◽

Rapid Compression

The development of internal combustion engines involves various new solutions, one of which is the use of dual-fuel systems. The diversity of technological solutions being developed determines the efficiency of such systems, as well as the possibility of reducing the emission of carbon dioxide and exhaust components into the atmosphere. An innovative double direct injection system was used as a method for forming a mixture in the combustion chamber. The tests were carried out with the use of gasoline, ethanol, n-heptane, and n-butanol during combustion in a model test engine—the rapid compression machine (RCM). The analyzed combustion process indicators included the cylinder pressure, pressure increase rate, heat release rate, and heat release value. Optical tests of the combustion process made it possible to analyze the flame development in the observed area of the combustion chamber. The conducted research and analyses resulted in the observation that it is possible to control the excess air ratio in the direct vicinity of the spark plug just before ignition. Such possibilities occur as a result of the properties of the injected fuels, which include different amounts of air required for their stoichiometric combustion. The studies of the combustion process have shown that the combustible mixtures consisting of gasoline with another fuel are characterized by greater combustion efficiency than the mixtures composed of only a single fuel type, and that the influence of the type of fuel used is significant for the combustion process and its indicator values.

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Numerical Simulation of Premixed Propane/Air Flame Propagation Using a Dynamically Thickened Flame Approach

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.444-445.1574 ◽

2013 ◽

Vol 444-445 ◽

pp. 1574-1578 ◽

Cited By ~ 1

Author(s):

Hua Hua Xiao ◽

Zhan Li Mao ◽

Wei Guang An ◽

Qing Song Wang ◽

Jin Hua Sun

Keyword(s):

Numerical Simulation ◽

Flame Propagation ◽

Numerical Study ◽

Vortex Motion ◽

Combustion Process ◽

Single Step ◽

Premixed Combustion ◽

Premixed Flame ◽

Flame Surface ◽

Arrhenius Kinetics

A numerical study of premixed propane/air flame propagation in a closed duct is presented. A dynamically thickened flame (TF) method is applied to model the premixed combustion. The reaction of propane in air is taken into account using a single-step global Arrhenius kinetics. It is shown that the premixed flame undergoes four stages of dynamics in the propagation. The formation of tulip flame phenomenon is observed. The pressure during the combustion process grows exponentially at the finger-shape flame stage and then slows down until the formation of tulip shape. After tulip formation the pressure increases quickly again with the increase of the flame surface area. The vortex motion behind the flame front advects the flame into tulip shape. The study indicates that the TF model is quite reliable for the investigation of premixed propane/air flame propagation.

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