Home – Home – Jornals – Combustion, Explosion and Shock Waves 2025 number 3

The dynamics of gas temperature was studied using as an example a single cylindrical channel with a diameter of 2 mm - a Raschig ring - placed in a porous medium made of such rings. The gas and thermocouple wire temperatures on the channel axis and the temperature distribution in the channel were calculated for two processes: the first is the pressure rise in a closed vessel during flame propagation in the space free of the porous medium, and the second is the cooling of the gas after the flame passage through the channel. For both processes, the gas temperature and the equilibrium temperature of the gas and the porous medium were measured using a thermocouple with a wire diameter of 15 μm in a cylindrical pore with a diameter of 2 mm. It was shown that during gas compression at a constant low rate, the thermocouple provided adequate measurements of steady-state gas temperature. However, when reaching the steady-state value, the larger the wire diameter, the longer was the thermocouple lag. During cooling of the instantaneously heated gas, the thermocouple measurements of gas temperature were found to be significantly underestimated. This is due to the higher heat capacity of the thermocouple wire as compared to the heat capacity of the gas in the pore. During the heating of the thermocouple, the gas cools down due to heat transfer into the pore walls.