Direct numerical simulation of micro combustion in a narrow circular channel with a detailed kinetic mechanism

Miyata, Eriko; Fukushima, Naoya; Naka, Yoshifumi; Shimura, Masayasu; Tanahashi, Mamoru; Miyauchi, Toshio

doi:10.1016/j.proci.2014.07.057

Cited by 53 publications

(42 citation statements)

References 18 publications

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“…The "FREI" phenomenon was also experimentally found and studied by Stazio et al [53] for a methane/air premixed flame in a 2.15-mm inner diameter straight tube with a prescribed wall temperature profile maintained by an external heating source, Richecoeur et al [54] for a non-premixed methane/oxygen flame in a 4-mm inner diameter curved duct without external heating, and Evans et al [55] for rich methane and propane/oxygen flames in 4-mm inner diameter non-externally-heated ducts made of different materials of quartz, glass and steel. Apart from experimental studies, the "FREI" was also successfully reproduced in numerical simulations [56][57][58][59][60][61][62].…”

Section: Fundamental Studiesmentioning

confidence: 87%

“…When a particular species data was not available, Sutherland's three coefficient law (based on kinetic theory) [84] was used to calculate transport properties. It should be noted that other studies [56,61,62,68,71,80] have incorporated the CHEMKIN code [85] to evaluate the thermodynamic and transport properties for each species. CHEMKIN used essentially the same thermodynamic database and only a slightly different fitting procedure from the CEA code by Gordon and McBride [83].…”

Section: Numerical Solvermentioning

confidence: 99%

“…-Wall: A hyperbolic tangent temperature profile ramping from 300 K to 1400 K is prescribed, as done in previous works [56,59,61].…”

Section: Numerical Solvermentioning

confidence: 99%

“…Since only a few of the past studies used the GCI method, visual observations of the solutions might have a less strict requirement on grid refinement. Moreover, the geometries/dimensions of the domain, reaction schemes used and spatial accuracy of the solver (for example, higher order schemes could allow for coarser mesh density to maintain the spatial accuracy [56,61]) are also considered to be factors which affect the required mesh densities. However, the main point here is that the GCI method used in this paper is a proper way to quantify the discretisation errors during the mesh refinement process.…”

Section: Grid Resolutionmentioning

confidence: 99%

“…On the other hand, numerical models do not make such assumptions and are capable of quantitatively revealing detailed physical features and can therefore be used as a reliable tool that develops the understanding of current configurations and supports the design of future systems. Some past numerical simulations using a steady-state [48,[68][69][70][71][72][73] or transient [56,61,62,[74][75][76][77][78] model were conducted, with a focus on the flame stabilities and flame dynamics.…”

Section: Introductionmentioning

confidence: 99%

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Micro/mesoscale combustion based portable power generating system

Kang¹

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Micro/mesoscale combustion-driven power generation is a promising alternative to replace traditional batteries for powering small scale electronics owing to its much higher energy densities. However, the considerable heat losses from the combustor walls due to the dramatically increased surface-tovolume ratio, as well as the short flow residence time at small scales pose a technical challenge in stabilising the flame inside the micro/mesoscale combustor. On the other hand, the significantly enhanced flame-wall thermal coupling at small scales can also lead to some unique flame characteristics.Recently, solid state power conversion of the heat released in the micro/mesoscale combustor such as thermoelectric (TE) and thermophotovoltaic (TPV) has been favoured over traditional power conversion methods such as micro-turbines. This is due to the excessive mechanical and viscous losses that rotating machinery suffers from upon miniaturisation.One of the main aims of this thesis is to perform numerical simulations to investigate the fundamental aspects of micro/mesoscale combustion, such as micro-flame behaviours of propagation and stabilisation, the conditions under which flame dynamics occur and the choices that suppress them. A set of modelling techniques that gives guidelines and practices for performing the time-accurate micro/mesoscale combustion simulations has been developed through investigation. Knowledge on standard and well-accepted numerical methods in literature are collected in a cohesive document. The less well-established modelling choices have been thoroughly evaluated and discussed.Using the developed numerical models, the effects of hydrogen and carbon monoxide addition on premixed methane/air flame dynamics is investigated. Results show that the flame instabilities which exist in pure methane/air flames could be effectively suppressed via a small amount of additives. Deep understanding of the underlying physics and chemistry has been gained. The effects of wall temperature profiles on the simulated micro-flame behaviours are also studied. The role of the combustion heat release and the gas-solid heat transfer in determining the micro-flame propagation speed is identified.Experimental works are also carried out, towards a full system demonstration for micro-power generation. The focus is placed on the "wall thermal engineering" on the improvement of the combustor performance and power output. The thermally-orthotropic pyrolytic graphite for the combustor wall material is explored. Compared to an isotropic material of stainless steel, a widened flame stability limit with pyrolytic graphite is demonstrated. Moreover, a uniform and moderate temperature distribution over the combustor surface is achieved, which is favourable for thermoelectric power conversion applications. Meanwhile, a novel, compact mesoscale thermophotovoltaic power generating system using a combination of porous media combustion and a simple band-pass filtering method is developed. The use of the porous media effectively enh...

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