3. Blast wave following deflagration in free space

3.1 Piston model

In the ideal case, a flame propagating in a combustible gas mixture towards the fresh gases is characterized by a smooth front and a velocity known as the fundamental laminar flame velocity, S _L (m.s ^-1 ).

In the case of a spherically propagating flame in the absence of confinement, the fundamental velocity S _L is different from the space velocity due to the change in thermodynamic conditions on either side of the flame front. The release of heat due to the chemical reaction implies an increase in temperature, and therefore in molar volume. As a result, the observed flame front propagation velocity V...