Simulation of Hot-Jet Ignition in a Heated Constant-Volume Combustor Using Adadptive Mesh Refinement and Multi-Zone Reaction

2014 ◽  
Author(s):  
Manikanda K. Rajagopal ◽  
Mohamed R. Nalim ◽  
Md Nazmuzzaman Khan
Keyword(s):  
Mesh Refinement ◽  
Constant Volume ◽  
Hot Jet Ignition

scholarly journals Traversing Hot-Jet Ignition in a Constant-Volume Combustor

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
Abdullah Karimi ◽  
Manikanda Rajagopal ◽  
Razi Nalim
Keyword(s):  
High Speed ◽  
Internal Combustion Engines ◽  
Combustion Products ◽  
Combustible Mixture ◽  
Constant Volume ◽  
Atmospheric Conditions ◽  
Wave Rotor ◽  
Numerical Predictions ◽  
Stable Species ◽  
Hot Jet Ignition

Hot-jet ignition of a combustible mixture has application in internal combustion engines, detonation initiation, and wave rotor combustion. Numerical predictions are made for ignition of combustible mixtures using a traversing jet of chemically active gas at one end of a long constant-volume combustor (CVC) with an aspect ratio similar to a wave rotor channel. The CVC initially contains a stoichiometric mixture of ethylene or methane at atmospheric conditions. The traversing jet issues from a rotating prechamber that generates gaseous combustion products, assumed at chemical equilibrium for estimating major species. Turbulent combustion uses a hybrid eddy-breakup model with detailed finite-rate kinetics and a two-equation k-ω model. The confined jet is observed to behave initially as a wall jet and later as a wall-impinging jet. The jet evolution, vortex structure, and mixing behavior are significantly different for traversing jets, stationary centered jets, and near-wall jets. Pressure waves in the CVC chamber affect ignition through flame vorticity generation and compression. The jet and ignition behavior are compared with high-speed video images from a prior experiment. Production of unstable intermediate species like C2H4 and CH3 appears to depend significantly on the initial jet location while relatively stable species like OH are less sensitive.

scholarly journals Ignition by Hot Transient Jets in Confined Mixtures of Gaseous Fuels and Air

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Abdullah Karimi ◽  
M. Razi Nalim
Keyword(s):  
Reaction Mechanism ◽  
Reaction Rate ◽  
Numerical Study ◽  
Combustion Products ◽  
Combustible Mixture ◽  
Constant Volume ◽  
Initial Reaction ◽  
Ignition Process ◽  
Gaseous Fuels ◽  
Hot Jet Ignition

Ignition of a combustible mixture by a transient jet of hot reactive gas is important for safety of mines, prechamber ignition in IC engines, detonation initiation, and novel constant-volume combustors. The present work is a numerical study of the hot jet ignition process in a long constant-volume combustor (CVC) that represents a wave rotor channel. The hot jet of combustion products from a prechamber is injected through a converging nozzle into the main CVC chamber containing a premixed fuel-air mixture. Combustion in a two-dimensional analogue of the CVC chamber is modeled using a global reaction mechanism, a skeletal mechanism, or a detailed reaction mechanism for three hydrocarbon fuels: methane, propane, and ethylene. Turbulence is modeled using the two-equation SSTk-ωmodel, and each reaction rate is limited by the local turbulent mixing timescale. Hybrid turbulent-kinetic schemes using some skeletal reaction mechanisms and detailed mechanisms are good predictors of the experimental data. Shock wave traverse of the reaction zone is seen to significantly increase the overall reaction rate, likely due to compression heating, as well as baroclinic vorticity generation that stirs and mixes reactants and increases flame area. Less easily ignitable methane mixture is found to show slower initial reaction and greater dependence on shock interaction than propane and ethylene.

scholarly journals Traversing Hot-Jet Ignition in a Constant-Volume Combustor

2013 ◽  
Author(s):  
Abdullah Karimi ◽  
Manikanda Rajagopal ◽  
Razi Nalim
Keyword(s):  
High Speed ◽  
Combustion Products ◽  
Combustible Mixture ◽  
Constant Volume ◽  
Atmospheric Conditions ◽  
Wave Rotor ◽  
Numerical Predictions ◽  
Stable Species ◽  
Hot Jet Ignition ◽  
Combustible Mixtures

Hot-jet ignition of a combustible mixture has application in IC engines, detonation initiation, and wave rotor combustion. Numerical predictions are made for ignition of combustible mixtures using a traversing jet of chemically active gas at one end of a long constant-volume combustor (CVC) with aspect ratio similar to a wave rotor channel. The CVC initially contains a stoichiometric mixture of ethylene or methane at atmospheric conditions. The traversing jet issues from a rotating pre-chamber that generates gaseous combustion products, assumed at chemical equilibrium for estimating major species. Turbulent combustion uses a hybrid eddy-break-up model with detailed finite-rate kinetics and a two-equation k-ω model. The confined jet is observed to behave initially as a wall jet and later as a wall-impinging jet. The jet evolution, vortex structure and mixing behavior are significantly different for traversing jets, stationary centered jets, and near-wall jets. Pressure waves in the CVC chamber affect ignition through flame vorticity generation and compression. The jet and ignition behavior are compared with high-speed video images from a prior experiment. Production of unstable intermediate species like C2H4 and CH3 appears to depend significantly on the initial jet location while relatively stable species like OH are less sensitive.

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