A comparative study of the combustion dynamics and flame properties of dead Mediterranean plants

Abstract

Background The physical processes governing flame behaviour are key elements for a better understanding of forest fires.Aims To study the combustion properties of several dead Mediterranean forest fuels.Method Samples of straw, eucalyptus, shrubs and Pinus Pinaster with the same load were placed in circular containers of the same size, and ignited in the absence of wind.Key results The combustion parameters (burning rate, flame height, temperature and gas velocity) evolved according to the same trend regardless of the fuel type. A new law is proposed to account for the anomalous relaxation processes occurring in the growth and decay phases of the flame. The dynamic exponent depends on the vegetation type only in the growth phase (highest for Pinus Pinaster and lowest for straw). The relaxation times are shortest for shrubs and largest for straw. The maximum flame height and burning rate are largest for shrubs and lowest for straw. Froude modelling suggests that the scaling behaviour of the flame may depend on the fuel type.Conclusions The observed relaxation parameters driving fire dynamics and the combustion characteristics depend on the nature of the fuel.Implications Further investigation of the vegetation region’s influence on these properties is necessary.