A Study on Detonation of Jet-A Using a Reduced Mechanism

2010 ◽  
Author(s):  
Kumud Ajmani ◽  
Krishna Kundu ◽  
Paul Penko
Keyword(s):  
Reduced Mechanism

Development of a reduced mechanism of a three components surrogate fuel for the coal-to-liquid and diesel combustion simulation

Fuel ◽  
2021 ◽  
Vol 294 ◽  
pp. 120370
Author(s):  
Shaodian Lin ◽  
Wanchen Sun ◽  
Liang Guo ◽  
Peng Cheng ◽  
Yuxiang Sun ◽  
...  
Keyword(s):  
Diesel Combustion ◽  
Reduced Mechanism ◽  
Combustion Simulation ◽  
Surrogate Fuel ◽  
Three Components

scholarly journals Numerical study of flame structure in the mild combustion regime

2015 ◽  
Vol 19 (1) ◽  
pp. 21-34 ◽  
Author(s):  
Amir Mardani ◽  
Sadegh Tabejamaat
Keyword(s):  
Fuel Injection ◽  
Numerical Study ◽  
Flame Structure ◽  
Combustion Regime ◽  
Low Oxygen ◽  
Mixing Rate ◽  
Jet Flame ◽  
Reduced Mechanism ◽  
Mild Combustion ◽  
O2 Concentration

In this paper, turbulent non-premixed CH4+H2 jet flame issuing into a hot and diluted co-flow air is studied numerically. This flame is under condition of the moderate or intense low-oxygen dilution (MILD) combustion regime and related to published experimental data. The modelling is carried out using the EDC model to describe turbulence-chemistry interaction. The DRM-22 reduced mechanism and the GRI2.11 full mechanism are used to represent the chemical reactions of H2/methane jet flame. The flame structure for various O2 levels and jet Reynolds numbers are investigated. The results show that the flame entrainment increases by a decrease in O2 concentration at air side or jet Reynolds number. Local extinction is seen in the upstream and close to the fuel injection nozzle at the shear layer. It leads to the higher flame entertainment in MILD regime. The turbulence kinetic energy decay at centre line of jet decreases by an increase in O2 concentration at hot Co-flow. Also, increase in jet Reynolds or O2 level increases the mixing rate and rate of reactions.

Evaluation of Kinetic Mechanisms for Direct Fired Supercritical Oxy-Combustion of Natural Gas

2016 ◽  
Author(s):  
Shane Coogan ◽  
Xiang Gao ◽  
Aaron McClung ◽  
Wenting Sun
Keyword(s):  
Carbon Dioxide ◽  
Natural Gas ◽  
San Diego ◽  
Laminar Flame ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Validation Data ◽  
Data Set ◽  
Reduced Mechanism ◽  
Kinetic Mechanisms

Existing kinetic mechanisms for natural gas combustion are not validated under supercritical oxy-fuel conditions because of the lack of experimental validation data. Our studies show that different mechanisms have different predictions under supercritical oxy-fuel conditions. Therefore, preliminary designers may experience difficulties when selecting a mechanism for a numerical model. This paper evaluates the performance of existing chemical kinetic mechanisms and produces a reduced mechanism for preliminary designers based on the results of the evaluation. Specifically, the mechanisms considered were GRI-Mech 3.0, USC-II, San Diego 204-10-04, NUIG-I, and NUIG-III. The set of mechanisms was modeled in Cantera and compared against the literature data closest to the application range. The high pressure data set included autoignition delay time in nitrogen and argon diluents up to 85 atm and laminar flame speed in helium diluent up to 60 atm. The high carbon dioxide data set included laminar flame speed with 70% carbon dioxide diluent and the carbon monoxide species profile in an isothermal reactor with up to 95% carbon dioxide diluent. All mechanisms performed adequately against at least one dataset. Among the evaluated mechanisms, USC-II has the best overall performance and is preferred over the other mechanisms for use in the preliminary design of supercritical oxy-combustors. This is a significant distinction; USC-II predicts slower kinetics than GRI-Mech 3.0 and San Diego 2014 at the combustor conditions expected in a recompression cycle. Finally, the global pathway selection method was used to reduce the USC-II model from 111 species, 784 reactions to a 27 species, 150 reactions mechanism. Performance of the reduced mechanism was verified against USC-II over the range relevant for high inlet temperature supercritical oxy-combustion.

scholarly journals Reduced Mechanism Approach of Modeling Premixed Propane-Air Mixture Using ANSYS Fluent

2012 ◽  
Vol 16 (1) ◽  
pp. 67-86 ◽  
Author(s):  
Lucky Anetor ◽  
Edward Osakue ◽  
Christopher Odetunde
Keyword(s):  
Ansys Fluent ◽  
Reduced Mechanism

Analysis of Autoignition Chemistry in Aeroderivative Premixers At Engine Conditions

2021 ◽  
Author(s):  
Sandeep Jella ◽  
Gilles Bourque ◽  
Pierre Gauthier ◽  
Philippe Versailles ◽  
Jeffrey M. Bergthorson ◽  
...  
Keyword(s):  
Residence Time ◽  
Real Life ◽  
Precursor Chemistry ◽  
Mode Analysis ◽  
Safety Factors ◽  
Eddy Simulation ◽  
Reduced Mechanism ◽  
Short Period ◽  
Large Eddy ◽  
Pure Methane

Abstract The minimization of autoignition risk is critical to premixer design. Safety factors based on ignition delays of homogeneous mixtures, are generally used to guide the choice of a residence time for a given premixer. However, autoignition chemistry at aeroderivative conditions is fast (0.5-2 milliseconds) and can be initiated within typical premixer residence times. The analysis of what takes place in this short period involves the study of low-temperature precursor chemistry. By coupling the evolution of the Chemical Explosive Modes to turbulence, it is possible to obtain a measure of spatial autoignition risk where both chemical (e.g. ignition delay) and aerodynamic (e.g. local residence time) influences are unified. In this article, we describe a method that couples Large Eddy Simulation to newly developed, reduced autoignition chemical kinetics to study autoignition precursors in an example premixer representative of real life geometric complexity. A blend of pure methane and dimethyl ether (DME), a common fuel used for experimental autoignition studies, was transported using the reduced mechanism (38 species / 238 reactions) at engine conditions at increasing levels of DME concentration until exothermic autoignition kernels were formed. The Chemical Explosive Mode analysis closely follows the large thermochemical changes in the premixer as a function of DME concentration and identifies where the premixer is sensitive and flame anchoring is likely to occur.

scholarly journals Design, Optimization, and Experiment on a Bioinspired Jumping Robot with a Six-Bar Leg Mechanism Based on Jumping Stability

2020 ◽  
Vol 2020 ◽  
pp. 1-23 ◽  
Author(s):  
Ziqiang Zhang ◽  
Bin Chang ◽  
Jing Zhao ◽  
Qi Yang ◽  
Xingkun Liu
Keyword(s):  
Dynamic Models ◽  
Rotation Angle ◽  
High Sensitivity ◽  
Optimization Method ◽  
Small Range ◽  
Configuration Optimization ◽  
Inertia Moment ◽  
Object A ◽  
Reduced Mechanism ◽  
Optimization Parameters

A jumping leg with one degree of freedom (DOF) is characterized by high rigidity and simple control. However, robots are prone to motion failure because they might tip over during the jumping process due to reduced mechanism flexibility. Mechanism design, configuration optimization, and experimentation were conducted in this study to achieve jumping stability for a bioinspired robot. With locusts as the imitated object, a one-DOF jumping leg mechanism was designed taking Stephenson-type six-bar mechanism as reference, and kinematic and dynamic models were established. The rotation angle of the trunk and the total inertia moment were used as stability criteria, and the sensitivity of different links to the target was analyzed in detail. With high-sensitivity link lengths as the optimization parameters, a configuration optimization method based on the particle swarm optimization algorithm was proposed in consideration of the different constraint conditions of the jumping leg mechanism. Optimization results show that this method can considerably improve optimization efficiency. A prototype of the robot was developed, and the experiment showed that the optimized trunk rotation angle and total inertia moment were within a small range and can thus meet the requirements of jumping stability. This work provides a reference for the design of jumping and legged robots.

Modeling Static Instabilities of Biogas Flames in a Stirred-Reactor Using Detailed Chemical Kinetics Simulations

2013 ◽  
Author(s):  
Christopher D. Bolin ◽  
Abraham Engeda
Keyword(s):  
Gas Turbines ◽  
Static Stability ◽  
Gas Turbine Combustor ◽  
Detailed Chemical Kinetics ◽  
Reduced Mechanism ◽  
Stirred Reactor ◽  
Primary Zone ◽  
Stability Limits ◽  
Different Sources ◽  
Detailed Chemical

Kinetic modeling of lean static stability limits of the combustion of biogas type fuels in a model of an ideal primary zone of a gas turbine combustor is presented here. In this study, CH4 is diluted with CO2 to simulate a range of gases representative of the products of anaerobic digestion of organic materials from different sources (e.g., landfill and animal waste digester). Fuels of this type are of interest for use in small gas turbines used in distributed generation applications. Predictions made by two detailed mechanisms (GRI-Mech 3.0 and San Diego) and one reduced mechanism (GRI-Mech 1.2, reduced) are employed to investigate the underlying kinetics near lean extinction. Approximate correlations to lean extinction are extracted from these results and compared to those of other fuels.

A Stochastic Simulation of an HCCI Engine Using an Automatically Reduced Mechanism

2001 ◽  
Author(s):  
Hakan Serhad Soyhan ◽  
Terese Løvås ◽  
Fabian Mauss
Keyword(s):  
Flow Reactor ◽  
Plug Flow ◽  
High Sensitivity ◽  
Ignition Process ◽  
Compression Ignition ◽  
Detailed Chemical Kinetics ◽  
Promising Alternative ◽  
Hcci Engine ◽  
Reduced Mechanism ◽  
Skeletal Mechanism

Abstract Homogeneous Charge Compression Ignition (HCCI) Engines are a promising alternative to the existing Spark Ignition Engines and Compression Ignition Engines. In an HCCI engine, the premixed fuel/air mixture ignites when sufficiently high temperature and pressure is reached. The entire bulk will auto-ignite at almost the same time because the physical conditions are similar throughout the combustion chamber. Therefore it is a justified assumption to consider the chemical reactions to be the rate-determining step for the ignition process. This gives us the opportunity to formulate a simple zero-dimensional model with detailed chemical kinetics for the calculations of the ignition process. Ignition calculations using this model have predicted a high sensitivity to fluctuations in temperature and fuel compositions. These predictions have later been confirmed by experiments. Partially stirred plug flow reactor (PaSPFR) can be used to conquer the assumption of homogeneity. The assumption is replaced by that of statistical homogeneity and thus statistical fluctuations caused by inhomogeneities can be studied. However, the CPU-time needed for this approach is increased considerably and the usage of mechanism reduction becomes evident. In this paper, we demonstrate how a reduced mechanism for natural gas as fuel is derived automatically. The original mechanism by Warnatz (589 reactions, 53 species) is first reduced to a skeletal mechanism (481 reactions, 43 species). By introduction of the quasi steady state assumption, the skeletal mechanism is reduced further to 23 species and 20 global reactions. The accuracy of the final mechanism is demonstrated using the stochastic reactor tool for an HCCI engine.

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