摘要:

The paper presents experimental results of the study, in a “well stirred reactor”, of the combustion of hydrocarbons with air. Particular care had been taken in the realization of a good “stirring”, or homogenization, of the combustor, and in the minimization of heat losses. The evolution of the CO, CO2, H2species during the combustion of CH4, C3H8, CH4+ H2mixture, benzene and isooctane has been measured as a function of residence time for reaction extents from 0.50 to 0.95, according to the cases, and for equivalence ratio from 0.65 to 1.20. These experimental results have been exploited with a view to leading to a “quasi global” schematization of the complex chemical processes of combustion, for which the numerical values of the corresponding constants have been obtained; a computer programme has been deducted from that scheme, which yielded a rather satisfactory agreement with experimental results. Although relatively simplified, this schematization can already be used with reasonable safety for predicting the performance of burners and combustors, particularly of turbomachine combustors.

ISSN:0010-2202    

DOI:10.1080/00102208108946941

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Regression rates of a hypergolic combination of fuel and oxidiser have been experimentally measured as a function of chamber pressure, mass flux and the percentage component of the hypergolic compound in natural rubber. The hypergolic compound used is difurfurylidene cyclohexanone (DFCH) which is hypergolic with the oxidiser red fuming nitric acid (RFNA) with ignition delay of 60-70 ms. The data of weight loss versus time is obtained for burn times varying between 5 and 20 seconds. Two methods of correlating the data using mass flux of oxidiser and the total flux of hot gases have shown that index n of the regression law ṙ=aGoxnor ṙ=aGnxa−1(x the axial distance) is about 0.5 or a little lower and not 0.8 even though the flow through the port is turbulent. It is argued that the reduction of index n is due to heterogeneous reaction between the liquid oxidiser and the hypergolic fuel component on the surface.

ISSN:0010-2202    

DOI:10.1080/00102208108946942

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

A numerical model which can be used to study some aspects of mass fires is presented. The k—ϵ model of turbulence and the flame sheet model of combustion are employed. To account for the “unmixed-ness” of the fuel and oxidant, a fraction of oxygen is treated as inert while radiative loss is modelled by assuming that a fraction of the locally released heat is lost by radiation. The source is taken as a 200 m wide strip constant source of mass in a uniform cross flow stably stratified atmosphere. The conditions assumed in this testing of the model are of the order encountered in large mass fires. Results indicate that although qualitatively the predictions are similar to those of a constant temperature source there are some significant differences, the most outstanding ones being: (1) a more defined downward “jet point” and upstream transition zone; and (2) high velocities within the source of the order reported in large mass fires. The main contribution of this effort is that a simple scheme can be used to study mass fire phenomena.

ISSN:0010-2202    

DOI:10.1080/00102208108946943

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Laser-induced ionization signals are observed in a premixed C2H2/air flame at the sooting limit and are attributed to thermal ionization of very small particles. The mobilities of these species are derived from ion velocity measurements and compared with the mobility of Na+for identical flame conditions. From a series of measured mobilities, estimates are made for the particle mass (2300-6100 amu) and diameter (1.6-2.2 nm). This experimental method is thus a new optical means for probing the early stages of soot formation.

ISSN:0010-2202    

DOI:10.1080/00102208108946944

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

To close the turbulent combustion equations, the time mean chemical source terms must be estimated. This paper reports the measurements of saturation ion current in the turbulent premixed flame to obtain the mean turbulent reaction rate. Detailed measurements were carried out of mean, rms and probability density functions of saturation ion current using a water-cooled electrostatic probe. For the wrinkled laminar flame model, the saturation ion current is shown to be proportional to the mean turbulent reaction rate. Roughly linear relationship is found between the mean saturation ion current and mean temperature, which results in an important fact that mean turbulent reaction rate is proportional to mean temperature. This Fact supports the Eddy-Break-Up model 3-peak PDF of saturation ion current is observed on the burnt side of the turbulent flame zone, each peak corresponding to unburnt gas, burnt gas and laminar flame zone, and confirms that the present turbulent premixed flame zone is composed of the wrinkled laminar flame.

ISSN:0010-2202    

DOI:10.1080/00102208108946945

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

This paper reports experimental results on the existence of multiple steady states in a catalytic combustor for various inlet temperatures (Tin), velocities (Vin), and equivalence ratios (φin). The catalyst was comprised of binary transition metal oxides (CO3O4, Cr2O3) supported on alumina wash-coated ceramic honeycomb substrates. Only oxidation of lean propane-air mixtures (equivalence ratios ⩽0.2) were studied.

ISSN:0010-2202    

DOI:10.1080/00102208108946946

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

A quasisteady-gas-phase and thermally-thin-substrate model is used to analyze the transient behavior of catalytic monolith combustors in fuel-lean operation. The combustor response delay is due to the substrate thermal inertia. Fast response is found to be favored by thin substrate, short catalytic bed length, high combustor inlet and final temperatures and, in most cases, small gas channel diameters. The calculated gas and substrate temperature time history at different axial positions provide an understanding of how the catalytic combustor responds to an upstream condition change. The computed results also suggest that the gas residence times in the catalytic bed and in the after-bed space are correlatable with the nondimensional combustor response time. When fast transient responses are required, both steady and unsteady studies have to be made to achieve a meaningful compromising design.

ISSN:0010-2202    

DOI:10.1080/00102208108946947

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Measurements are described in which the effect of intense microwave fields (≃2 × 105V/m) upon flame velocities in acetylene-air, ethylene-air and propane-air mixtures was determined. The measurements extend those reported in a previous paper in which no enhancement of velocity was observed with the application of miciowave radiation (<2x 104 V/m). The more intense fields were capable of producing gas breakdown behind the flame front and for these circumstances flame speed enhancement of up to ∼40 percent was observed. However when gas breakdown did not occur a smaller (<20 percent for ethylene, <10 percent for propane and acetylene flames) enhancement was observed. Also, it was only for very lean mixtures that there was flame speed enhancement; the maximum enhancement occurring just slightly rich of the lean limit. Because the large flame velocity enhancement was observed only when gas breakdown took place and as such a large amount of rf power was delivered to the flame, the application of this effect to augment flame speed in a practical situation is not encouraging.

ISSN:0010-2202    

DOI:10.1080/00102208108946948

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The kinetics of the reaction of limestone/dolomite with H2S have been examined under fuel rich combustion conditions. The experiments were done in a tubular laminar flow reactor with co-current flow of gas and solids.

ISSN:0010-2202    

DOI:10.1080/00102208108946949

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor