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Mixing and combustion of gas jets
Başlık:
Mixing and combustion of gas jets
Yazar:
Goudie, George O., author.
ISBN:
9780438052789
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (349 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Advisors: James Small.
Özet:
This thesis is an attempt to put into perspective various theories and measurements of the length of diffusion flames. It is concluded that, in addition to the state of the gas stream, the steadiness of the air surrounding the gas jet is an important factor determining the flame behaviour. The earliest attempt to predict diffusion flame shape from diffusion theory is discussed. This theory is then evaluated to show how the general behaviour of diffusion flames is controlled by burner geometry and gas properties. The very rigid assumptions inherent in this theory include uniformity of gas and air velocity throughout the burner system. An apparatus is devised which is aimed to produce diffusion flames under conditions which are controlled as far as possible to those specified for the above theory, although some conditions cannot be adhered to (e.g. a uniform temperature and the specified absence of pre-flame reactions). Measurements of diffusion flame length under these controlled conditions are described. It is shown that the steadiness of the flame defines the limit within which the general predictions of the theory are borne out in practice; the theory specifies laminar mixing, which ceases to control mixing completely when the flame becomes unsteady. More specifically, as expected the theory fails to predict flame lengths accurately on the basis of 'cold' diffusion data. An attempt is then made to assess theoretically the effect, on the diffusion process in general and the flame length in particular, of changing the flow conditions of the air surrounding the gas stream. When control over the air supply is relaxed completely, so that air diffuses into the gas jet freely from the surrounding atmosphere, it is shown that, in theory, little change in the general behaviour of the diffusion flame should result. This prediction conflicts with authoritative published measurements of the length of these ''open" flames, although other measurements tend to support the theoretical prediction. Further measurements of open diffusion flames are made in an attempt to resolve this apparent contradiction. It is established that again theory explains flame behaviour as long as the flames are steady. Beyond this limit, which in certain circumstances is imposed by the break-down from laminar flow, only empirical predictions have so far explained the flame behaviour, and no satisfactory theory is to be expected until the mechanism of mixing in the transition and turbulent regions of gas flow has been elucidated. In other circumstances extinction or vibrations destroy the steadiness of the flame.
Notlar:
School code: 0547
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(684424.1) | 684424-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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