Variation in the heat exchange of combustion products over an oscillation period during vibrational flame propagation

1978 ◽  
Vol 34 (5) ◽  
pp. 607-609
Author(s):  
D. S. Kayumova ◽  
S. A. Abrukov
Keyword(s):  
Heat Exchange ◽  
Flame Propagation ◽  
Combustion Products ◽  
Oscillation Period

scholarly journals The influence of the charge shape on heat exchange of a recessed nozzle

2021 ◽  
Vol 2057 (1) ◽  
pp. 012013
Author(s):  
B Ya Benderskiy ◽  
A A Chernova
Keyword(s):  
Heat Exchange ◽  
Power Plant ◽  
Combustion Products ◽  
Triangular Form ◽  
Topological Features ◽  
Exchange Processes ◽  
Charge Shape ◽  
Intensification Of Heat Exchange ◽  
Thermally Conductive ◽  
Control Volumes

Abstract The paper deals with the numerical simulation of the flow of thermally conductive viscous gaseous combustion products in the flow paths of a power plant. The influence of the shape of the mass supply surface on the gas dynamics and heat exchange near the recessed nozzle of the power plant is investigated. The coupled problem of heat exchange is solved by the method of control volumes. It is shown that the compensator geometry determines the localization of both the topological features of the flow near the recessed nozzle and the position of local maximums of the heat transfer coefficient. It has been revealed that The use of a channel with a star-shaped cross section and a triangular form of compensator rays leads to an intensification of heat exchange processes near a recessed nozzle.

Flammability properties of fire-retardant timber

2021 ◽  
Vol 30 (2) ◽  
pp. 23-34
Author(s):  
O. N. Korolchenko ◽  
S. G. Tsarichenko ◽  
N. I. Konstantinova
Keyword(s):  
Mass Loss ◽  
Flame Propagation ◽  
Flame Retardants ◽  
Fire Retardant ◽  
Combustion Products ◽  
Timber Structures ◽  
Measurement Instruments ◽  
Pine Tree ◽  
Smoke Generation ◽  
Oak Tree

Introduction. At present, the house-building industry, that produces timber structures, is in the process of sufficiently intensive development; however, high flammability of wood is the factor that restrains widespread use of timber in construction. The purpose of this work is to optimize the conditions of application of fire-retardant timber in the construction industry. The co-authors believe that the following problems are to be solved to attain this objective:● a comparative analysis of the fireproofing efficiency of several fire-proofing agents applied to different species of wood;● determination of the character of influence produced by fire proofing agents on fire retardant properties of wood.Methods of research. The fire proofing efficiency of sample compositions designated for wood was measured in compliance with the benchmark testing method specified in GOST R 53292 (p. 6.2). Experiments were launched pursuant to the methodology and with the help of measurement instruments specified in GOST 30244–94 (Method 2) to study the extent of the pine-tree timber flammability suppression. Critical values of thermal loads that may trigger inflammation and flame propagation in timber structures, that can be described using values of the critical surface density of the heat flow, were determined pursuant to GOST 30402–96 and GOST R 51032–97. The toxicity of combustion products and the smoke generation ability of fire-retardant pine-tree samples was assessed using standard methods and measurement instruments pursuant to GOST 12.1.044–89 (paragraphs 4.18 and 4.20).Research results and discussion. Biological flame retardants, integrated biological flame retardants that also ensure moisture protection, intumescent coatings, lacquers and varnishes that are ready for use and labelled as having group I and II fire-retardant efficiency pursuant to GOST R 53292, were studied in the course of this research project. The co-authors have identified that the mass loss by all fire-retardant compositions is below 9 %, if applied to samples of larch and oak-tree timber, same as if it were applied to standard samples of pine-tree timber.The findings of the experiment conducted to assess the flammability, ignitibility, flame propagation, smoke generation ability and toxicity of combustion products have proven the maximal efficiency of the composition designated for full-cell pressure impregnation of timber that ensures the properties of the material labelled as G1, V1, RP1, T2, D2.Conclusions. Hence, the research results have enabled the co-authors to assess the discrepancy between average mass loss values demonstrated by the samples of different species of timber (alder, linden, pine-tree, larch, and oak-tree).The comprehensive study of flammability properties of timber, treated by compositions that vary in their chemical composition and mode of action of the fire proofing agent, enabled the co-authors to identify the impact produced by versatile fire-proofing agents on different flammability properties of pine-tree timber with regard taken of the fire-safe use of construction materials and constructions of buildings and structures.

Cyclic flame propagation in premixed combustion

2013 ◽  
Vol 735 ◽  
pp. 176-202 ◽  
Author(s):  
Philipp A. Boettcher ◽  
Shyam K. Menon ◽  
Brian L. Ventura ◽  
Guillaume Blanquart ◽  
Joseph E. Shepherd
Keyword(s):  
Flame Propagation ◽  
Propagation Speed ◽  
Power Input ◽  
Combustion Products ◽  
Flame Speed ◽  
Field Analysis ◽  
Gravitational Acceleration ◽  
Inflow Velocity ◽  
Hot Surface ◽  
Flame Propagation Speed

AbstractIn experiments of hot surface ignition and subsequent flame propagation, a puffing flame instability is observed in mixtures that are stagnant and premixed prior to ignition. By varying the size of the hot surface, power input, and combustion vessel volume, it was determined that the instability is a function of the interaction of the flame, with the fluid flow induced by the combustion products rather than the initial plume established by the hot surface. Pressure ranges from 25 to 100 kPa and mixtures of n-hexane/air with equivalence ratios between $\phi = 0. 58$ and 3.0 at room temperature were investigated. Equivalence ratios between $\phi = 2. 15$ and 2.5 exhibited multiple flame and equivalence ratios above $\phi = 2. 5$ resulted in puffing flames at atmospheric pressure. The phenomenon is accurately reproduced in numerical simulations and a detailed flow field analysis revealed competition between the inflow velocity at the base of the flame and the flame propagation speed. The increasing inflow velocity, which exceeds the flame propagation speed, is ultimately responsible for creating a puff. The puff is then accelerated upward, allowing for the creation of the subsequent instabilities. The frequency of the puff is proportional to the gravitational acceleration and inversely proportional to the flame speed. A scaling relationship describes the dependence of the frequency on gravitational acceleration, hot surface diameter, and flame speed. This relation shows good agreement for rich n-hexane/air and lean hydrogen/air flames, as well as lean hexane/hydrogen/air mixtures.

scholarly journals NOVEL TRENDS OF DEVELOPMENT AND PERFECTION THE MODERN HEAT EXCHANGERS

2019 ◽  
pp. 54-65
Author(s):  
B.S. Soroka
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Exchange Process ◽  
Combustion Products ◽  
Reynolds Analogy ◽  
Heat Exchange Equipment ◽  
Heat Exchange Process ◽  
Heat Transfer Phenomenon ◽  
Relative Change

Some actual aspects of advancement the problem of improvement the heat exchange equipment are considered in the paper. First of all the actual items related to middle and high temperature recuperators are discussed with proper up-to — date approaches. The classification of flue gases heat recovery appliances has been proposed along with the statement and analysis of the main characteristics of the recovery plants and option the ways of optimization the mentioned characteristics. The problem of Reynolds analogy (similarity of relative change the heat transfer phenomenon and variation the hydraulic resistance) within the channels of different purpose and of various cross-section supplied with and without the obstacles has been analyzed in application to separate cases of flow along the surfaces equipped with the cavities (dimples) or the convex elements. Thermal Performance Factor (TPF) of the heat exchange process is qualitatively like to Reynolds analogy factor and is highly depended upon rate of heat transfer and of friction factor in conditions of the scheme under consideration for flow over the surface or flow within the channel. The various media has been compared used as a working body in the heat exchanger’s channels: gaseous, liquid and the nanofluids, the last appeared in practice since 2000. Analysis has been carried out on effect of using the secondary energy emitters (SEE) arranged inside the tube channels, on resulting heat flux by heat exchange between outward flow of combustion products and the inner air flow. Bibl. 23, Fig. 6.

Influence of Active Particles of Combustion Products on the Speed of Flame Propagation in a Turbulent Flow

ARS Journal ◽  
1962 ◽  
Vol 32 (1) ◽  
pp. 133-137 ◽  
Author(s):  
V. YA. BASEVICH ◽  
M. I. DEVISHEV ◽  
S. M. KOGARKO
Keyword(s):  
Turbulent Flow ◽  
Flame Propagation ◽  
Combustion Products ◽  
Active Particles

Numerical Simulation of a Reacting Jet in a Vitiated Cross Flow Using a Novel Progress Variable Approach

2017 ◽  
Author(s):  
Rohit Kulkarni ◽  
John P. Wood ◽  
Mario Zuber ◽  
Hasan U. Karim
Keyword(s):  
Flame Propagation ◽  
Gas Turbines ◽  
Accurate Determination ◽  
Cross Flow ◽  
Combustion Products ◽  
Combustion Model ◽  
Progress Variable ◽  
Variable Approach ◽  
Auto Ignition ◽  
Lifted Flames

Staged/sequential combustion is a state of the art method to provide operational flexibility and reduced emissions in gas turbines. To use Computational Fluid Dynamics (CFD) to study such systems a reliable and computationally inexpensive turbulent combustion model is necessary. A key requisite for such a model is the accurate determination of the flame location in order to predict emissions, flame dynamics, and temperature distribution. Previously a model was developed for reheat combustion, based on a progress-variable method using auto-ignition reactors. However, sequential combustion systems are now being implemented where both auto-ignition and flame propagation are important. Consequently, the reheat model has been extended to consider flame propagation in mixtures that do not auto-ignite. This has been achieved by incorporating a small proportion of combustion products in the reactant mixture considered by the reactor. This approach has broadened the model’s applicability to address the full space between auto-ignition and flame propagation regimes. The revised model has been validated by comparison with reacting jet in vitiated cross-flow experiments demonstrating a significantly better prediction of the position of both attached and lifted flames than the original model.

scholarly journals Numerical modeling of radiation heat exchange in combustion chambers and heat exchangers of power installations

2020 ◽  
Vol 209 ◽  
pp. 03018
Author(s):  
Nikolay Moskalenko ◽  
Ibragim Dodov ◽  
Azat Akhmetshin
Keyword(s):  
Numerical Modeling ◽  
Heat Exchange ◽  
Radiation Heat Transfer ◽  
Combustion Products ◽  
Spectral Lines ◽  
Spectral Transmission ◽  
Radiation Heat ◽  
Combustion Chambers ◽  
Two Phase ◽  
Radiation Heat Exchange

The application of numerical modeling is considered to solve the problems of radiation heat exchange in structurally inhomogeneous two-phase media which are realized during the combustion of fuel in boiler units atmospheric emissions from air carriers when they move at supersonic speeds. The optically active ingredients of the gas phase of the combustion products have a sharp selection of spectral absorption lines (radiation) which causes a difference in the spectral transmission functions for selective radiation from the spectral transmission functions for non-selective radiation (gray body). In the presence of a dispersed phase of the combustion products acute selection is subjected to such a parameter of the radiation propagation medium as the probability of quantum survival. The number of spectral lines determining the spectral transmission functions increases with temperature and is determined by hundreds of thousands of lines at high temperatures. In this paper we consider a closed simulation of radiation heat transfer in combustion chambers when the temperature field in the combustion chambers is calculated first and then the flux of thermal radiation to the tube heat-receiving surfaces.

scholarly journals Optimization of the built-in recuperator surface of recuperative burner according to the criterion of energy coefficient maximum

Vestnik IGEU ◽  
2020 ◽  
pp. 5-11
Author(s):  
A.B. Biryukov ◽  
A.N. Lebedev ◽  
P.A. Gnitiev ◽  
Ya.S. Vlasov
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchange ◽  
Transfer Coefficient ◽  
Fuel Consumption ◽  
Thermal Power ◽  
Aerodynamic Resistance ◽  
Combustion Products ◽  
Energy Coefficient ◽  
The Heat Transfer Coefficient

The recuperative burners is a modern direction of reducing fuel consumption during the heat treatment of metals in furnaces. Their use can significantly reduce fuel consumption. Despite the evident advantages, the spread of such equipment is constrained due to its high cost. The research is conducted for determining ribs rational profile and optimizing mass and size characteristics of a built-in recuperator. There are results that make it possible to reduce either the recuperator mass or its aerodynamic resistance. However, such changes contradict each other, so a compromise solution must be found. Currently, there are no generally accepted methods of thermotechnical calculations for recuperative burners. This work aims to develop a methodology to optimize the built-in recuperator surface according to the criterion of maximizing the energy coefficient. To conduct the study, the elements of recuperative heat exchange theory for counter-flow media were used. The proven methodology for determining the temperature of heated air and cooled combustion products after recuperator was applied. Also, the known concept of energy coefficient was used for the research. A technique has been developed to optimize the surface of the incorporated heat exchanger according to the criterion of maximizing the energy coefficient. The technique includes composing an expression for determining the energy coefficient, taking its derivative and equating it to zero with further solving the obtained equation with respect to heat exchange surface. The developed method was used in the recuperative burner with the thermal power of 500 kW. For the range of heat transfer coefficient 75–200 W/(m2·K) associated to the smoothtube part, a fifth-degree polynomial has been determined which describes the dependence of the smoothtube part optimal value of a built-in recuperator surface on the heat transfer coefficient. The developed technique is important for recuperative burners design, for increasing their efficiency and reducing their production cost. The methodology error associated with the assumption that the heat transfer coefficient is constant when the length of the built-in recuperator changes does not exceed 5 %.

Morphologic, chemical, and spectral analyses of combustion products of micro- and nano-dispersed particles of aluminium borides

2019 ◽  
Vol 484 (1) ◽  
pp. 44-47
Author(s):  
D. A. Yagodnikov ◽  
Sh. L. Guseinov ◽  
P. A. Storozhenko ◽  
A. P. Shpara ◽  
A. V. Sukhov ◽  
...  
Keyword(s):  
Flame Propagation ◽  
Combustion Products ◽  
Mass Spectrometric ◽  
Spectral Analyses ◽  
Dispersed Particles ◽  
Air Suspension ◽  
Condensed Combustion Products

This study presents the findings of an investigation of flame propagation in air suspension of nanodispersed polyboride particles, and provides spectral, morphological, and mass-spectrometric analyses of condensed combustion products generated during an air suspension combustion.

Sign in / Sign up

Export Citation Format

Share Document