Different stages of flame acceleration from slow burning to Chapman-Jouguet deflagration
Artikel i vetenskaplig tidskrift, 2009

Numerical simulations of spontaneous flame acceleration are performed within the problem of flame transition to detonation in two-dimensional channels. The acceleration is studied in the extremely wide range of flame front velocity changing by 3 orders of magnitude during the process. Flame accelerates from realistically small initial velocity (with Mach number about 10(-3)) to supersonic speed in the reference frame of the tube walls. It is shown that flame acceleration undergoes three distinctive stages: (1) initial exponential acceleration in the quasi-isobaric regime, (2) almost linear increase in the flame speed to supersonic values, and (3) saturation to a stationary high-speed deflagration velocity. The saturation velocity of deflagration may be correlated with the Chapman-Jouguet deflagration speed. The acceleration develops according to the Shelkin mechanism. Results on the exponential flame acceleration agree well with previous theoretical and numerical studies. The saturation velocity is in line with previous experimental results. Transition of flame acceleration regime from the exponential to the linear one, and then to the constant velocity, happens because of gas compression both ahead and behind the flame front.

walls

tubes

flames

Mach number

nonslip

supersonic

turbulent

mixture

flow

radiated sound

transition

channels

large-eddy simulation

chemically reactive flow

detonation

combustion

Författare

D. M. Valiev

Umea universitet

The Royal Institute of Technology (KTH)

V. Bychkov

Umea universitet

V. Akkerman

Umea universitet

Princeton University

Lars-Erik Eriksson

Chalmers, Tillämpad mekanik, Strömningslära

Physical Review E - Statistical, Nonlinear, and Soft Matter Physics

1539-3755 (ISSN)

Vol. 80

Ämneskategorier

Fysik

DOI

10.1103/PhysRevE.80.036317