Scalar predictors of premixed gas ignition by a suddenly-starting hot jet

This paper presents a numerical study on fuel injection, ignition and combustion in a direct-injection natural gas (DING) engine with ignition assisted by a shielded glow plug (GP). The shield geometry is investigated by employing different sizes of elliptical shield opening and changing the position of the shield opening. The results simulated by KIVA-3V indicated that fuel ignition and combustion is very sensitive to the relative angle between the fuel injection and the shield opening, and the use of an elliptical opening for the glow plug shield can reduce ignition delay by 0.1∼0.2ms for several specific combinations of the injection angle and shield opening size, compared to a circular shield opening. In addition, the numerical results also revealed that the natural gas ignition and flame propagation will be delayed by lowering a circular shield opening from the fuel jet center plane, due to the blocking effect of the shield to the fuel mixture, and hence it will reduce the DING performance by causing a longer ignition delay.

Download Full-text

XXXV. The thermal theory of gas ignition by electric sparks

The London Edinburgh and Dublin Philosophical Magazine and Journal of Science ◽

10.1080/14786442508634610 ◽

1925 ◽

Vol 49 (290) ◽

pp. 323-336 ◽

Cited By ~ 3

Author(s):

J.D. Morgan

Keyword(s):

Thermal Theory ◽

Gas Ignition

Download Full-text

Validation of the ASVDADD Constraint Selection Algorithm for Effective RCCE Modeling of Natural Gas Ignition in Air

Journal of Energy Resources Technology ◽

10.1115/1.4038376 ◽

2017 ◽

Vol 140 (5) ◽

Cited By ~ 2

Author(s):

Luca Rivadossi ◽

Gian Paolo Beretta

Keyword(s):

Natural Gas ◽

Nox Formation ◽

Accurate Identification ◽

Thermodynamic Conditions ◽

Gas Ignition ◽

Detailed Kinetic Model ◽

The Individual ◽

Value Decomposition ◽

Constraint Selection ◽

Hydrocarbon Ignition

The rate-controlled constrained-equilibrium (RCCE) model reduction scheme for chemical kinetics provides acceptable accuracies in predicting hydrocarbon ignition delays by solving a smaller number of differential equations than the number of species in the underlying detailed kinetic model (DKM). To yield good approximations, the method requires accurate identification of the rate controlling constraints. Until recently, a drawback of the RCCE scheme has been the absence of a systematic procedure capable of identifying optimal constraints for a given range of thermodynamic conditions and a required level of approximation. A recent methodology has proposed for such identification an algorithm based on a simple algebraic analysis of the results of a preliminary simulation of the underlying DKM, focused on the degrees of disequilibrium (DoD) of the individual chemical reactions. It is based on computing an approximate singular value decomposition of the actual degrees of disequilibrium (ASVDADD) obtained from the DKM simulation. The effectiveness and robustness of the method have been demonstrated for methane/oxygen ignition by considering a C1/H/O (29 species/133 reactions) submechanism of the GRI-Mech 3.0 scheme and comparing the results of a DKM simulation with those of RCCE simulations based on increasing numbers of ASVDADD constraints. Here, we demonstrate the new method for shock-tube ignition of a natural gas/air mixture, with higher hydrocarbons approximately represented by propane according to the full (53 species/325 reactions) GRI-Mech 3.0 scheme including NOx formation.

Download Full-text

Modeling of Ignition and Combustion for Glow Plug Assisted Direct Injection Natural Gas Engines

ASME 2012 Internal Combustion Engine Division Fall Technical Conference ◽

10.1115/icef2012-92099 ◽

2012 ◽

Cited By ~ 4

Author(s):

Stewart Xu Cheng ◽

James S. Wallace

Keyword(s):

Natural Gas ◽

Heated Surface ◽

Direct Injection ◽

Cfd Modeling ◽

Spontaneous Ignition ◽

Layer Model ◽

Glow Plug ◽

Natural Gas Engines ◽

Gas Ignition ◽

Ignition And Combustion

Direct injection natural gas (DING) engines offer the advantages of high thermal efficiency and high power output compared to spark ignition natural gas engines. Injected natural gas requires some form of ignition assist in order to ignite in the time available in a diesel engine combustion chamber. A glow plug — a heated surface — is one form of ignition assist. Simple experiments show that the thickness of the heat penetration layer of a glow plug is very small (≈10−5 m) within the time scale of the ignition preparation period (1–2 ms). Meanwhile, the theoretical analyses reveal that only a very thin layer of the surrounding gases (in micrometer scale) can be heated to high temperature to achieve spontaneous ignition. A discretized glow plug model and virtual gas sub-layer model have been developed for CFD modeling of glow plug ignition and combustion for DING diesel engines. In this paper, CFD modeling results are presented. The results were obtained using a KIVA3 code modified to include the above mentioned new developed models. Natural gas ignition over a bare glow plug was simulated. The results were validated against experiments. Simulation of natural gas ignition over a shielded glow plug was also carried out and the results illustrate the necessity of using a shield. This paper shows the success of the discretized glow plug model working together with the virtual gas sub-layer model for modeling glow plug assisted natural gas direct injection engines. The modeling can aid in the design of injection and ignition systems for glow plug assisted DING engines.

Download Full-text

An Annular Combustor Natural Gas Ignition Model Derived From Atmospheric Sector Experiments

Volume 1: Turbo Expo 2002 ◽

10.1115/gt2002-30073 ◽

2002 ◽

Cited By ~ 1

Author(s):

C. Hirsch ◽

T. Ku¨enzi ◽

H. P. Kno¨pfel ◽

B. Paikert ◽

C. Steinbach ◽

...

Keyword(s):

Equivalence Ratio ◽

Mixing Model ◽

Operating Conditions ◽

Flammability Limits ◽

Basic Physics ◽

Annular Combustor ◽

Pilot Fuel ◽

Gas Ignition ◽

Ignition Limits ◽

Burner Operation

Results from ignition and cross-ignition tests performed on an atmospheric 60°-sector test rig equipped with three EV-type burners are presented. Based on these results a model was developed for an annular combustor, which calculates the primary ignition and burner-burner cross-ignition limits for the combustor in terms of burner operation variables (equivalence ratio and pilot fuel ratio) using a generally applicable methodology described in the paper. Key ingredients of the model are the description of mixture flammability and a mixing model representing the ignition relevant mixing behaviour of the burners in the annular combustor. Ignition and cross-ignition are observed to occur, if the mixture equivalence ratio determined from the mixing model is above the flammability limits calculated for the particular operating conditions. Even in the case of cross iginition across an externally piloted or switched-off burner, the model reproduces the experimental cross-ignition limits, confirming that the basic physics have been captured.

Download Full-text

Hot-gas ignition of non-premixed methane flames in the presence of inert particles

Proceedings of the Combustion Institute ◽

10.1016/j.proci.2004.08.053 ◽

2005 ◽

Vol 30 (1) ◽

pp. 431-437 ◽

Cited By ~ 1

Author(s):

Mustafa G. Andac ◽

Fokion N. Egolfopoulos ◽

Charles S. Campbell

Keyword(s):

Hot Gas ◽

Inert Particles ◽

Gas Ignition ◽

Methane Flames

Download Full-text