Pressure modeling of upward flame spread and burning rates over solids in partial gravity

Abstract

Pressure–gravity modeling is proposed as a means to simulate upward flame spread and burning rates over vertical solid samples in partial gravity environments, such as on the Moon and on Mars. Based on experimental results in reduced gravity, the upward flame spread rate data over thin solids can be correlated by the expression p 1.8 g (where p is the ambient pressure and g is the gravity level). This is close to the theoretical p 2 g factor in preserving the Grashof number and is also supported by detailed numerical simulations. Since the flame size, shape and standoff distance are preserved in this simulation, it is expected that combustion properties controlled chiefly by convective heat transfer are properly accounted for by the present technique. This includes upward flame spread rates, growth rates, and burning rates over thin and thick solids in both laminar and turbulent flames. In flames where the heat transfer is dominated by soot emission, more studies are needed to verify the validity of this correlation.