Turbulent Combustion of Hydrogen–CO Mixtures

Abstract

Laminar and turbulent burning velocities were measured in a closedvolume fan-stirred vessel for H 2 -CO mixtures using two independent methods of flame definition. It has been shown that the unsteady flame development is an important factor and it needs to be taken into account for comparison of the burning rates obtained in different experiments. For the atmospheric pressure flames, the mixtures with faster laminar flame velocities burnt faster in turbulent flow despite the fact that the lean flames exhibit cellular structures. However, even a modest increase of the initial pressure promotes strongly cellularity and causes a significant acceleration of a lean laminar flame. The same lean flame burns faster in turbulent flow as well and this increase in the rate of combustion is greater that can be deduced from variation of the molecular heat diffusivity and laminar flame speed.

Structure of turbulent rich hydrogen-air premixed flames

“…However, the cellularity had not been especially discussed on turbulent premixed flames albeit some flame images with cellularity could be found in the literature about displacement speeds of turbulent premixed flames with hydrogen contained. [16][17][18][19] Wrinkling is another notable character of turbulent hydrogen-contained premixed flames' structure, and it is related to both cellularity and turbulence. [20][21][22][23] Heretofore, the wrinkling level of premixed flames had been experimentally studied by many previous scholars from different viewpoints like local curvature structure, 21 fractal analysis, 24 and even spectrum analysis.…”

“…From the reports about previous studies on laminar hydrogen‐contained premixed flames, it could be known that hydrogen‐air premixed flames were more obviously cellular than the others with same initial conditions; adding hydrogen into other fuels could induce fiercer cellularity than their intrinsic, and such results were mainly attributed to the instabilities of hydrogen‐air premixed flame. However, the cellularity had not been especially discussed on turbulent premixed flames albeit some flame images with cellularity could be found in the literature about displacement speeds of turbulent premixed flames with hydrogen contained …”

Turbulent burning rates of gasoline components, Part 1 – Effect of fuel structure of C6 hydrocarbons

“…This is explained as 'turbulent flame development', when the flame kernel is small only a proportion of the turbulent eddies (those smaller than the flame) can wrinkle the flame, increasing its surface area and hence its burning velocity [21]. As the flame grows more eddies are able to wrinkle the flame and it accelerates, the flame brush thickness has also been shown to increase with flame radius [22]. [27] and to a lesser extent laminar flame speed [28].…”

Measurement of the laminar burning velocities and markstein lengths of lean and stoichiometric syngas premixed flames under various hydrogen fractions

“…Given the increasing concerns on energy efficiency and environmental protection, synthesis gas (syngas) has attracted significant interests as a promising alternative and environmentally clean fuel in the field of energy and combustion [1,2]. Syngas primarily consists of hydrogen and carbon monoxide and can be derived from numerous sources, such as coal, coke, natural gas and heavy oil; there is a considerable variation in the H 2 /CO ratio of syngas due to various sources and processing methods.…”