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- Publisher
- Emerald Publishing
- Copyright
- Copyright © Emerald Group Publishing Limited
- ISSN
- 0002-2667
- DOI
- 10.1108/eb032635
- Publisher site
- See Article on Publisher Site
Abstract
CONFERENCE REPORT Anglo-American Conference relevant to aero-engines also. Data for flame on Combustion emissivities and heat transfer coefficients are given. In the final paper, distinguished by the elegance of its literary style, Probert discusses the A Report on the Conference Organized Jointly by the Institution of Mechanical application of research to gas-turbine com bustion problems, including in his review Engineers and the American Society of Mechanical Engineers atomization, droplet distribution, vaporization and burning, and scale effects, particular atten tion being paid to the work of the N.G.T.E. in By D. B. Spalding, M.A., Ph.D. this field. The experiments which he reports on the stability of geometrically similar pilot flames will interest engineers who are concerned with model tests on reaction-limited flames. Everyone S was announced in the June 1955 issue of is space to mention only two papers. The first, will not agree in all respects with the author's AIRCRAFT ENGINEERING, this conference by McInerney, Mattocks and Newby, gives data interpretation of these results. was held in Boston, Massachusetts in June, for the momentum and entrainment of various and again in London in October. oil-burners of the two-fluid type, i.e. those using Conclusions a fluid such as steam to atomize the fuel. The International conferences on combustion have second, by Jack, Kruszewski and Richardson, been frequent in recent years. The one held this In the discussion at Boston, Lloyd drew atten describes a technique for predicting the flame year jointly by the I.Mech.E. and A.S.M.E. dif tion to the great contrast between the funda shape in glass tank furnaces by studying models in fered markedly from other recent meetings how mental and the applied papers, pointing out that ever, in that most of the papers were contributed which fuel gas and air are represented by streams they appeared to speak in two different languages. by men intimately concerned with using com of hot and cold water. This represents a very in He might have gone further and said that the bustion rather than merely observing it. The teresting development of the water model, pre users even of a single language spoke such varied papers presented cover a wide range of subjects. viously used only for flow pattern study. The dialects as scarcely to be able to understand each engine industry, which has already adopted the Here only those papers with a direct bearing on other. This theme was referred to several times in earlier technique, developed in connexion with aeronautical engineering will be mentioned. the London discussions; in concluding this re open-hearth steel furnaces, might profitably view it may be worth while unravelling some of make use of the new technique also. Admittedly the threads. General Papers the simulation of liquid fuel combustion is not so Attempted collaboration between scientists and easy as that of gases. Section 1 is devoted to general papers on com engineers in the gas turbine field has not always bustion science and its relation to practice. The succeeded in the past, with the result that many first American paper, by Lewis and von Elbe, engineers doubt whether scientists can aid them, Reciprocating Engines discusses qualitatively some problems of 'acade while many scientists prefer not to try. Apart mic' combustion, chiefly laminar and turbulent Two papers from Section 4 deserve mention, from the usual human reasons for such failure of flame propagation in pre-mixed gases. The both of them American. The first is that of contact, there are special ones which it is im second American contribution is by Sherman and Longwell and Weiss on heat-release rates in portant to recognize, concerned with the nature Reid, of Batelle, who make an extensive survey hydrocarbon combustion. Although originally of gas turbine combustion. of the scientific knowledge relevant to engineering placed in the internal combustion engine section, Firstly, gas turbine flame properties are deter combustion processes, with particular reference this paper was later transferred to section 5 on mined by physical processes under normal cir to solid fuel. This paper is notable for its frank gas turbines. The authors describe measurements cumstances, but by chemical processes under the conclusion that the effect of research on engineer of the reaction rates at extinction of hydrocarbon- extreme (high altitude) conditions which engines ing practice has been disappointingly slight, and air flames in a homogeneous steady-flow bomb. must now cope with. Unfortunately, however, it for its fair discussion of this sad fact. The authors Their data are the best that are available for use was the chemists who were called in in the early implicitly blame both engineers for not formulat in theories of extinction of aero-engine com days; they naturally found that they had little to ing carefully enough what they require of the bustion at high altitudes. The effects of initial do. By the time the extreme conditions began to scientists, and the latter for not presenting their temperature, pressure and air-fuel ratio are re be encountered, engineers had become convinced results in a usable way, but they also point ported. In this section also, Livengood, Toong, that flames could be understood in purely physical out that for example coal burning would be Rona, Taylor and Black describe experiments on terms (atomization, droplet vaporization, re scarcely less difficult even if the scientists had artificially induced pre-ignition in petrol engines, circulation, etc.) and are only now beginning to solved all their current problems and the en which are relevant to ignition by hot surfaces accept the fact that chemical reaction rates limit gineers understood the solutions; it is the in generally, a process which may sometimes occur engine performance. escapable presence of ash and its melting that in aero-engines. Although the experimental re Secondly, chemists are chiefly concerned with are the real bugbears. sults are interesting, the authors do not entirely the reactions that occur at relatively low tem succeed in explaining them. This is partly due to The general paper from the United Kingdom peratures, for it is only these that are slow enough the difficulty of defining the conditions occurring is in two parts. The first, by Egerton, surveys the to be easy to observe. Yet gas turbine flames are in the engine, but also, in the reviewer's opinion, knowledge compiled by chemists of the chemical now recognized to be governed by high-tempera to the inadequacy of the authors' theoretical reactions by which fuel is oxidized, emphasizing ture reactions on which chemists have no data to model. the inherent complexity of the subject and the speak of. This conclusion is being accepted with number of the unknowns. The second part, by all the more reluctance, because of the successful Saunders and the reviewer, attempts to relate the co-operation between engineers and chemists in Gas Turbines 'differential' phenomena of reaction, diffusion, the past on the problem of petrol-engine 'knock', conduction and flow to the 'integrated' pheno where low-temperature reactions are indeed de Section 5 on the gas turbine contains ten mena, represented by the flames occurrent in cisive. papers of which three will be mentioned here; engineering equipment. Emphasis is placed on the this time all are British. J. S. Clarke contributes Thirdly, many of the most pressing problems volumetric reaction rate curve of a combustible a discussion of the relation of specific heat release of combustion chamber designers, particularly in mixture, the way it depends on the state of the to pressure drop, in a paper containing many the industrial engine field, are not actually com mixture, and the way it influences various com detailed diagrams of flow patterns in gas turbine bustion problems at all, but relate to secondary bustion phenomena. combustion chambers. Data are also given for phenomena such as flame radiation, ash deposi the mean velocity, temperature and pressure dis tion, corrosion, etc. In dealing with these pro tribution in a typical chamber. The dynamics of blems the engineer may well obtain help from Combustion in Boilers droplets in idealized models of the flow are dis scientists, but not however from the scientists Section 2 is on boilers, but contains one paper cussed and a relation between vaporization time assembled at the Combustion Conference, who and combustion efficiency is postulated. Limita likely to interest aeronautical engineers, namely had little knowledge of these things. tions imposed by chemical reaction rate are not that by Fraser on liquid-fuel firing. This contains In view of these considerations, and of the mentioned. quantitative data on the various methods of wide range of combustion equipment which was atomization. Heat transfer in gas turbine combustion discussed, it is not surprising that much of the chambers is discussed in a valuable paper by discussion was at cross-purposes. Nevertheless Tipler. This has a bias towards the industrial the reviewer believes that the conference did serve Industrial Furnaces to clarify the various issues and should help to engine and pays considerable attention to the make co-operation and mutual understanding Section 3 on industrial furnaces contains many refractory-lined and louvred chamber designs, more fruitful in the future. items of indirect aeronautical interest. Here there but the general methods and considerations are December 1955 403
Journal
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Dec 1, 1955