Abstract:

To investigate the energy release characteristics of extended sources in low-pressure environments, a combined experiment and simulation approach was adopted. Four typical altitude-corresponding pressures were selected as experimental conditions. An infrared thermal imager was employed to monitor parameters such as combustion temperature, radiance, and combustion area during the combustion process of the extended source. When the pressure decreases from 101 kPa to 30 kPa, the ignition time of the extended source doubles; the total energy release attenuates by 44.78%, and the combustion area reduces by 45.95%, but the fluctuations of peak temperature and average temperature are less than 3%, which indicates that the extended source maintains thermodynamic equilibrium by adjusting the infrared scale rather than the radiance. A simulation model was established based on heat and mass transfer governing equations and porous medium diffusion theory. The maximum error between the calculated results and experimental data is less than 13.07%, which verifies the reliability of the simulation model in predicting results within a wide range of pressure variation. The research results explain the energy release characteristics and variation laws of corresponding parameters of the extended source combustion system under different pressure states, providing support for the application and design optimization of extended sources in typical environments.

Key words: extended source combustion, low-pressure experiment, porous medium, heat and mass transfer, diffusion coefficient