An elementary model for autoignition of laminar jets.

Published on Jul 8, 2015
路 DOI :10.1098/rspa.2015.0059
Peter V. Gordon8
Estimated H-index: 8
(University of Akron),
Daniel J. Gotti1
Estimated H-index: 1
(USRA: Universities Space Research Association)
+ 3 AuthorsGregory I. Sivashinsky29
Estimated H-index: 29
(TAU: Tel Aviv University)
In this paper, we formulate and analyse an elementary model for autoignition of cylindrical laminar jets of fuel injected into an oxidizing ambient at rest. This study is motivated by renewed interest in analysis of hydrothermal flames for which such configuration is common. As a result of our analysis, we obtain a sharp characterization of the autoignition position in terms of the principal physical and geometrical parameters of the problem.
  • References (26)
  • Citations (4)
馃摉 Papers frequently viewed together
4 Citations
4 Citations
40 Citations
78% of Scinapse members use related papers. After signing in, all features are FREE.
#1Amable Li帽谩nH-Index: 24
#2Marcos Vera CoelloH-Index: 14
Last. Angel S谩nchez (Complutense University of Madrid)H-Index: 35
view all 3 authors...
This review uses as a vehicular example the jet-flame configuration to examine some phenomena that emerge in nonpremixed gaseous combustion as a result of the interaction between the temperature-sensitive chemical reaction, typical of combustion, and the convective and diffusive transport. These include diffusion-controlled flames, edge flames and their role in flame attachment, triple flames and their role as ignition fronts, and strain-induced extinction, including flame-vortex interactions. T...
29 CitationsSource
#1Uday G. HegdeH-Index: 5
#2D. GottiH-Index: 1
Last. Michael C. Hicks (Glenn Research Center)H-Index: 8
view all 3 authors...
Abstract Observations of near-critical water jets are reported in the injection Reynolds number range of approximately 300鈥3000 to characterize their transition to turbulence. Three types of cases are described: (i) subcritical jet injected into subcritical water, (ii) supercritical jet injected into supercritical water, and (iii) supercritical jet injected into subcritical water. In each case, the working pressure was kept above the critical value to eliminate two-phase effects. For cases (i) a...
5 CitationsSource
#1Peter V. Gordon (University of Akron)H-Index: 8
#2Vitaly Moroz (Swansea University)H-Index: 15
We consider a generalization of the Gelfand problem arising in Frank-Kamenetskii theory of thermal explosion. This generalization is a natural extension of the Gelfand problem to two-phase materials, where, in contrast to the classical Gelfand problem which uses a single temperature approach, the state of the system is described by two different temperatures. We show that similar to the classical Gelfand problem the thermal explosion occurs exclusively owing to the absence of stationary temperat...
3 CitationsSource
#1D. FongH-Index: 1
#2J. K. BechtoldH-Index: 1
Last. C. K. LawH-Index: 1
view all 3 authors...
We analyze the structure of laminar diffusion flames at high pressure in the limit of large activation energy for the particular configuration of a steady flame in counterflow. We consider a dense fluid in which normal Fickian diffusion of the fuel is limited, and thermal diffusion, i.e., the Soret effect, is the dominant mechanism for fuel mass transport. Temperature and species profiles, as well as flame temperature and location, are determined as a function of Damkohler number and Soret diffu...
4 CitationsSource
#1Chad Augustine (MIT: Massachusetts Institute of Technology)H-Index: 2
#2Jefferson W. Tester (MIT: Massachusetts Institute of Technology)H-Index: 46
Abstract Investigations of hydrothermal flames were reviewed with three primary objectives: (1) to classify and describe experiments performed to date, (2) to assess the state of the art of experimental instruments and measurement techniques, and (3) to characterize current understanding and outline future research needs of hydrothermal flame processes. For this review, hydrothermal flames are defined as rapid oxidation reactions occurring in a supercritical aqueous environment at sufficient tem...
67 CitationsSource
#1Patrizia PucciH-Index: 36
#2James SerrinH-Index: 53
and Preliminaries.- Tangency and Comparison Theorems for Elliptic Inequalities.- Maximum Principles for Divergence Structure Elliptic Differential Inequalities.- Boundary Value Problems for Nonlinear Ordinary Differential Equations.- The Strong Maximum Principle and the Compact Support Principle.- Non-homogeneous Divergence Structure Inequalities.- The Harnack Inequality.- Applications.
379 Citations
#1K. Pr铆kopsk媒 (EPFL: 脡cole Polytechnique F茅d茅rale de Lausanne)H-Index: 1
#2B. Wellig (EPFL: 脡cole Polytechnique F茅d茅rale de Lausanne)H-Index: 2
Last. Ph. Rudolf von Rohr (EPFL: 脡cole Polytechnique F茅d茅rale de Lausanne)H-Index: 16
view all 3 authors...
Experimental results using a transpiring-wall reactor (TWR) for supercritical water oxidation (SCWO) containing a hydrothermal flame as an internal heat source are presented. Our reactor set-up is aimed at overcoming the problem of reactor fouling and plugging due to precipitation of salts. Two types of transpiring-wall elements with different porosity were investigated. Experiments with artificial wastewater containing methanol and sodium sulfate in concentrations up to 6 and 3 wt.%, respective...
71 CitationsSource
#1Michael C. Hicks (Glenn Research Center)H-Index: 8
#2R. W. Lauver (Glenn Research Center)H-Index: 2
Last. T. J. SikoraH-Index: 2
view all 4 authors...
ABSTRACT Tests designed to quantify the gravitational effects on thermal mixing and reactant injection in a Supercritical Water Oxidation (SCWO) reactor have recently been performed in the Zero Gravity Facility (ZGF) at NASA鈥檚 Glenn Research Center. An artificial waste stream, comprising aqueous mixtures of methanol, was pressurized to approximately 250 atm and then heated to 450掳C. After uniform temperatures in the reactor were verified, a controlled injection of air was initiated through a spe...
5 CitationsSource
#2Takashi UsuiH-Index: 2
Last. Hideo Sekino (Ebara Corporation)H-Index: 2
view all 6 authors...
Hydrothermal flames at 25 MPa supercritical water environment were investigated using a 4800 ml reaction tower, in which the sapphire windows were fitted for optical access. Down flowing hydrothermal flames were observed for oxidation of 2-propanol when the reactor was fed with inlet organic concentration higher than 2 vol% and air ratio higher than 1.8. Flame temperature, as high as 1100 掳C, was measured by means of a thermocouple and the temperature was found to be strongly influenced by air r...
65 CitationsSource
The paper starts with a short review on the history of PDEs and their related inequalities. We present a unified approach to the basic parabolic differential inequalities. It starts in Section 2 with the famous Lemma of Nagumo and leads to recent and new result on parabolic equations with singular nonlinear elliptic operators (7) that include the p-Laplacian and the operator of capillary surfaces. Sections 3 and 4 deal with the one-dimensional case and radial solutions. A Semi-Strong Minimum Pri...
6 CitationsSource
Cited By4
#2Yanhui LiH-Index: 7
Last. Jie ZhangH-Index: 11
view all 7 authors...
Supercritical hydrothermal combustion, a new and promising homogeneous combustion technology with a wide range of application scenarios and broad development prospects, provides creative ideas and means for the enhanced degradation of organic wastes, hydrothermal spallation drilling, thermal recovery of heavy oil, etc. This technology is elaborated upon in five parts: (1) introducing the main devices including semi-batch reactor and continuous reactor to study the hydrothermal flame in accordanc...
#1Michael C. Hicks (Glenn Research Center)H-Index: 8
#2U.G. Hegde (Case Western Reserve University)H-Index: 1
Last. J.J. KojimaH-Index: 1
view all 3 authors...
Abstract Results on the autoignition and stabilization of ethanol hydrothermal flames in a Supercritical Water Oxidation (SCWO) reactor operating at constant pressure are reported. The flames are observed as luminous reaction zones occurring in supercritical water; i.e., water at conditions above its critical point (approximately 22鈥塎Pa and 374鈥壜癈). A co-flow injector is used to inject fuel (inner flow), comprising an aqueous solution ranging from 20%-v to 50%-v ethanol, and air (annular flow) i...
2 CitationsSource
This paper is concerned with the study of autoignition of fully developed free round turbulent jets consisting of oxidizing and chemically reacting components. We derive an elementary, still experimentally feasible, model for autoignition of such jets and present analysis of this model. The derivation of the model is based on the well-established experimental fact that the fully developed free round turbulent jets, in a first approximation, have the shape of a conical frustum. Moreover, the velo...
2 CitationsSource
#1Sivamohan N. Reddy (IITR: Indian Institute of Technology Roorkee)H-Index: 12
#2Sonil Nanda (York University)H-Index: 20
Last. Janusz A. Kozinski (York University)H-Index: 33
view all 5 authors...
Abstract A novel concept was applied for the in situ study of the ignition of n -propanol鈥揳ir hydrothermal flames during supercritical water oxidation. An innovative experimental arrangement including NASA's supercritical water oxidation facility was used to study the effect of reactor and oxidant (air) temperature on the spontaneous ignition of hydrothermal flames. New data were obtained concerning time- and temperature-resolved profiles of n -propanol in hydrothermal flames. Transient temperat...
8 CitationsSource
This paper is concerned with the derivation and mathematical analysis of a model for autoignition of laminar co-flow jets. Such jets consist of two parts: an inner part with oxidizer that is surrounded by an outer part with fuel, or the reverse. To derive a model we use a combination of Burke--Schumann theory of diffusion flames and Semenov--Frank-Kamenerskii theory of thermal explosion. The main advantage of our model is that it gives a well-defined condition for autoignition of a jet. We provi...