Model equation for the probability distributions of the velocity and concentration during turbulent mixing and diffusion combustion of gases

Taking into account China's abundant coal resources, methanol and DME(Dimethyl Ether) obtained from coal are good alternative fuels. The research project is to utilize the fuel of DME and methanol in diesel engines for new combustion models PCCI (Premixed Charge Compression Ignition).The tests of the PCCI mode with different boundary conditions were studied on PCCI test bench. PCCI combustion is consisted of three stages: low temperature reaction of DME, high-temperature reaction of DME and diffusion combustion reaction of methanol. DME as combustion improver should be kept relatively low concentration, and with the decrease of methanol, its concentration need to be reduced. Methanol and formaldehyde are important parts of HC emission, their volume fraction was about 70%.

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Regimes of Unstable Expansion and Diffusion Combustion of a Hydrocarbon Fuel Jet

Combustion Explosion and Shock Waves ◽

10.1134/s0010508218030012 ◽

2018 ◽

Vol 54 (3) ◽

pp. 255-263 ◽

Cited By ~ 6

Author(s):

V. V. Lemanov ◽

V. V. Lukashov ◽

R. Kh. Abdrakhmanov ◽

V. A. Arbuzov ◽

Yu. N. Dubnishchev ◽

...

Keyword(s):

Hydrocarbon Fuel ◽

Diffusion Combustion ◽

Fuel Jet ◽

And Diffusion

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Evaluation of a hybrid kinetics/mixing-controlled combustion model for turbulent premixed and diffusion combustion using KIVA-II

10.2514/6.1990-2450 ◽

1990 ◽

Author(s):

H. NGUYEN ◽

MING-JYH WEY

Keyword(s):

Combustion Model ◽

Diffusion Combustion ◽

And Diffusion ◽

Turbulent Premixed

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Numerical study of mixing and diffusion combustion of gaseous fuels in channels

Combustion Explosion and Shock Waves ◽

10.1007/bf00749176 ◽

1988 ◽

Vol 24 (2) ◽

pp. 132-138

Author(s):

S. A. Zaitsev ◽

A. B. Lebedev

Keyword(s):

Numerical Study ◽

Diffusion Combustion ◽

Gaseous Fuels ◽

And Diffusion

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The modelling of turbulent premixed and diffusion combustion in the computation of engineering flows

Combustion and Flame ◽

10.1016/0010-2180(77)90101-8 ◽

1977 ◽

Vol 29 ◽

pp. 111-122 ◽

Cited By ~ 34

Author(s):

F.C. Lockwood

Keyword(s):

Diffusion Combustion ◽

And Diffusion ◽

Turbulent Premixed

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Local flow topology and velocity gradient invariants in compressible turbulent mixing layer

Journal of Fluid Mechanics ◽

10.1017/jfm.2015.235 ◽

2015 ◽

Vol 774 ◽

pp. 67-94 ◽

Cited By ~ 30

Author(s):

Navid S. Vaghefi ◽

Cyrus K. Madnia

Keyword(s):

Velocity Gradient ◽

Turbulent Mixing ◽

Probability Distributions ◽

Mixing Layer ◽

Contraction Rate ◽

Flow Topology ◽

Gradient Tensor ◽

Local Flow ◽

Turbulent Mixing Layer ◽

Turbulent Region

The local flow topology is studied using the invariants of the velocity gradient tensor in compressible turbulent mixing layer via direct numerical simulation (DNS) data. The topological and dissipating behaviours of the flow are analysed in two different regions: in proximity of the turbulent/non-turbulent interface (TNTI), and inside the turbulent region. It is found that the distribution of various flow topologies in regions close to the TNTI differs from inside the turbulent region, and in these regions the most probable topologies are non-focal. In order to better understand the behaviour of different flow topologies, the probability distributions of vorticity norm, dissipation and rate of stretching are analysed in incompressible, compressed and expanded regions. It is found that the structures undergoing compression–expansion in axial–radial directions have the highest contraction rate in locally compressed regions, and in locally expanded regions the structures undergoing expansion–compression in axial–radial directions have the highest stretching rate. The occurrence probability of different flow topologies conditioned by the dilatation level is presented and it is shown that the structures in the locally compressed regions tend to have stable topologies while in locally expanded regions the unstable topologies are prevalent.

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An Investigation of the Relation Between Combustion Phase and Emissions of ULSD and RME Biodiesel With a Common-Rail HSDI Diesel Engine

Volume 1: Applied Mechanics; Automotive Systems; Biomedical Biotechnology Engineering; Computational Mechanics; Design; Digital Manufacturing; Education; Marine and Aerospace Applications ◽

10.1115/esda2014-20067 ◽

2014 ◽

Cited By ~ 2

Author(s):

Hayder A. Dhahad ◽

Mohammed A. Abdulhadi ◽

Ekhlas M. Alfayyadh ◽

T. Megaritis

Keyword(s):

Diesel Engine ◽

Ignition Delay ◽

High Speed ◽

Fuel Injection ◽

High Load ◽

Diffusion Combustion ◽

Low Load ◽

Combustion Phase ◽

Hsdi Diesel Engine ◽

And Diffusion

This study investigates the effect of combustion phase (premixed and diffusion phases) duration on the emissions emitted from a high speed direct injection (HSDI) diesel engine fueled with neat (100%) rapeseed methyl ester (RME) and run at a constant speed (1500 rpm) with single injection strategy at constant fuel injection pressure (800 bar) and varying fuel injection timings (−12,−9,−6,−3,0) ATDC, for two loads (2.5 and 5 bars) BMEP. The obtained results were compared with those obtained when the engine run at the same conditions but with ultra-low sulfur diesel fuel (ULSD). In-cylinder pressure was measured and analyzed using (LABVIWE) program. calculation program specially written in (MATLAB) software was used to extract the apparent heat release rate, the ignition delay, combustion duration and specify the amount of heat released during the premixed and diffusion combustion phases (premixed burn fraction PMBF) and (diffusion burn fraction DBF). Emission measurements included; NOx, CO, THC, CO2 and smoke number (SN). The results showed that at high load, RME generate higher NOx, CO and THC. Measurements and calculations indicated that ignition delay of RME was shorter than that of ULSD, which means less PMBF. This conflicting effect is probably due to the advanced start of combustion (SOC) leading to higher combustion temperature inside the combustion chamber and there will be less time available to complete the combustion. The emission results at low load showed that NOx and CO, generated by RME were less than those generated by USLD. USLD produced soot more than RME at high load and less at low load.

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Deep Link Entropy for Quantifying Edge Significance in Social Networks

Applied Sciences ◽

10.3390/app112311182 ◽

2021 ◽

Vol 11 (23) ◽

pp. 11182

Author(s):

Seval Yurtcicek Ozaydin ◽

Fatih Ozaydin

Keyword(s):

Social Networks ◽

Large Scale ◽

Probability Distributions ◽

Political Polarization ◽

Quantum Networks ◽

Political Communications ◽

Wide Range ◽

Precise Quantification ◽

Diffusion In Networks ◽

And Diffusion

Through online political communications, fragmented groups appear around ideological lines, which might form echo chambers if the communications within like-minded groups are dominant over the communications among different-minded groups, potentially contributing to political polarization and extremism. The antidote is the interactions between individuals who constitute social bridges between different minded groups. Hence, exploring the significance of connections between the individuals of a network is a center of attraction especially for the global connectivity and diffusion in networks. Based on the divergence of probability distributions of pairs of nodes, Link Entropy (LE) is a recently proposed method outperforming the others in quantifying edge significance. In this work, considering that the adjacent nodes of the two nodes of an edge are also in charge in determining its significance, we propose the Deep Link Entropy (DLE) method for a more precise quantification through taking into account the uncertainty distributions of the adjacent nodes as well. We show experimentally that DLE significantly outperforms LE especially in large-scale complex network with several groups or communities. We believe our method contributes to not only online political communications but a wide range of fields from biology to quantum networks, where edge significance has an operational meaning.

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