Structure of shock and detonation waves propagating in hybrid methane/hydrogen/air/coal dust mixtures

A study of shock and detonation waves propagating in gaseous two-fuel \(\hbox {CH}_{{4}}/\hbox {H}_{{2}}\)/air mixtures and heterogeneous three-fuel \(\hbox {CH}_{{4}}/\hbox {H}_{{2}}\)/air/coal mixtures with the mean bulk density of the coal dust suspension equal to \(95{-}560\,\hbox {g/m}^{{3}}\) and with a particle size of \(0{-}200\,\upmu \hbox {m}\) is performed. The experiments are conducted in a vertical shock tube with a length of 6.75 m and a diameter of 70 mm. The detonation parameters measured in the experiments are compared with the calculated equilibrium thermodynamic values. It is found that the detonation wave parameters are mainly affected by methane and hydrogen rather than by the coal dust suspension. Decaying shock waves are as dangerous as detonation waves because blast wave reflections can initiate detonation. An increase in the hydrogen fraction in the mixture decreases the energy of initiation of \(\hbox {CH}_{{4}}/\hbox {H}_{{2}}\)/air and \(\hbox {CH}_{{4}}/\hbox {H}_{{2}}\)/air/coal mixtures, resulting in a greater hazard for the generation of shock and detonation waves in these mixtures.