The turbulent burning velocity of methanol–air mixtures

Abstract

Methanol is a sustainable and versatile alternative fuel for spark-ignition engines and other combustion applications. To characterize the combustion behavior of this fuel, a good understanding of the factors affecting its turbulent burning velocity is re-10 quired. This paper presents experimental values of the turbulent burning velocity of methanol-air mixtures obtained in a fan-stirred bomb, for u ′ = 2-6 m/s, φ= 0.8-1.4, T= 358 K and pressures up to 0.5 MPa. In combination with laminar burning velocity values previously obtained on the same rig, these measurements are used to provide better insight into the various factors affecting u t of methanol, and to assess to what degree 15 existing turbulent combustion models can reproduce experimental trends. It appeared that most models correctly accounted for the effects of turbulent rms velocity u ′ . With respect to the effects of φ and pressure, however, models accounting for flame stretch and instabilities, through the inclusion of model terms depending on thermodiffusive mixture properties and pressure, had a slight edge on simpler formulations.

Turbulent explosion characteristics of stoichiometric syngas

“…Learnt from Vancoillie et al, 22 an indicator (t a , the time when the rate of pressure rise reaches to 50%) was used to assess the acceptable level of such smoothing. Learnt from Vancoillie et al, 22 an indicator (t a , the time when the rate of pressure rise reaches to 50%) was used to assess the acceptable level of such smoothing.…”

“…Learnt from Vancoillie et al, 22 the variation of t a (of 5%) also could be taken as the criterion to evaluate the repeatability. Learnt from Vancoillie et al, 22 the variation of t a (of 5%) also could be taken as the criterion to evaluate the repeatability.…”

“…Compared to the raw curves, the smoothed pressure history trace had little changes but the smoothed pressure rise rate had an obvious variation. Learnt from Vancoillie et al, 22 an indicator (t a , the time when the rate of pressure rise reaches to 50%) was used to assess the acceptable level of such smoothing. To the given case (u' rms = 1.309 m/s, Y H2 = 50%, stoichiometric syngasair mixture), the value of t a varied to 12.437 ms (in the smoothed) from 12.677 ms (in the raw) with a standard deviation of 1.9%, such it was far less than the criterion of 5%, and thus the smoothing process could be regarded acceptable.…”

“…To the aspect of experiment repeatability, a turbulent explosion just has a sense of repeatability in statistic since any turbulent explosion cannot be absolutely repeated. Learnt from Vancoillie et al, 22 the variation of t a (of 5%) also could be taken as the criterion to evaluate the repeatability. Figure 3 shows the comparison on pressure rise from 5 "repeatable" explosion experiments of syngas.…”

Explosion Behaviour of 30% Hydrogen/70% Methane-Blended Fuels in a Weak Turbulent Environment

“…Meanwhile, the value of t a (defined as the time to reach a pressure rise of 50%) is around 22.480 ms with a maximum error of about −1.68% (which also exists at Series IV), namely, the uncertainty on ta induced by the systematic factor is about ±1.68. It should be emphasised that, learning from previous scholars [14,15], t a is one of the utmost important parameters to evaluate the repeatability of an explosion process, and the verification criterion on repeatability is commonly set at 5%. From the above statistic, it could be found that both the maximum errors of p max and t a are far less than 5%, namely, the turbulent explosion progress reported by the present article could be believed repeatable with acceptable uncertainty levels.…”