Measurements and simulations of mixing and autoignition of an n-heptane plume in a turbulent flow of heated air

Experimental Investigation of the Effects of Turbulence and Mixing on Autoignition Chemistry

“…Although this has been reported previously, e.g. in the CTHC apparatus [11,12,19], no results were made available. In this paper, we also present data concerning the temporal randomness (i.e.…”

“…These studies, together with complementary modelling efforts (as that of Markides et al [12], amongst others), have established that an increase in the bulk air velocity U air causes an increase in the autoignition length from injection L IGN , as well as in the associated residence time until autoignition τ IGN = L IGN /U air . This important finding is consistent with similar measurements of autoignition made in turbulent counterflowing jets of hydrogen and hot air [13,14], where it was demonstrated experimentally that increased turbulence in the air stream resulted in a higher critical temperature necessary for autoignition, thus suggesting an inhibiting effect of turbulence on the pre-ignition reactions.…”

“…Recent experimental studies of autoignition in the 'Confined Turbulent Hot Coflow' (CTHC) apparatus have considered the autoignition of hydrogen [11] and n-heptane [12] plumes released concentrically into coflows of turbulent preheated air. These studies, together with complementary modelling efforts (as that of Markides et al [12], amongst others), have established that an increase in the bulk air velocity U air causes an increase in the autoignition length from injection L IGN , as well as in the associated residence time until autoignition τ IGN = L IGN /U air .…”

Simulation of Hydrogen Auto-Ignition in a Turbulent Co-flow of Heated Air with LES and CMC Approach

“…For the n-heptane jet case, in equal velocity conditions in the same geometry, i.e. jet velocity equal to the co-flow velocity, the ignition length was captured well using RANS and CMC [7]. In the context of LES, the CMC model has been used to study methane flames (Sandia D [8], lifted flame stabilized by auto-ignition [9] and bluff-body flames [10,11]) with very good results.…”

LES-CMC Simulations of Different Auto-ignition Regimes of Hydrogen in a Hot Turbulent Air Co-flow

“…This discrepancy may be due to scalar dissipation model used in the present LES-CMC implementation. Note that RANS-CMC of n-heptane in the same geometry [46] has captured this trend after an effort to predict correctly the mean scalar dissipation (in inert flow), which gives credence to attributing the present discrepancy to the LES scalar dissipation rate model. Such a study is considered beyond the scope of the present paper.…”