ACTIVE COOLING AND THERMAL-STRESS REDUCTION IN A POROELASTIC HOLLOW SPHERE

Using the thermoporoelastic theory previously proposed, thermal stress es are analyzed that are induced in a fluid-saturated poroelastic holl ow sphere, whose inner surface is exposed to burning gas and the wall of which is cooled by the fluid injection from its outer surface. Two loading histories are considered: (i) the sphere is subjected to a sud den rise in temperature of the gas and simultaneously pressurized at i ts outer surface to cool the wall; and (ii) steady-state cooling is ab ruptly disturbed by a sudden loss of pressurization and after a while, is recovered. The main focus is on the effect of heat advection due t o active fluid injection on the reduction of temperature and thermal s tresses. Since the formulated problem is axisymmetric the displacement field is decoupled from the temperature and pore pressure fluids, whi ch are still coupled to each other The coupled nonlinear diffusion equ ations are solved by the Crank-Nicolson implicit method It has been co ncluded that the active fluid pressurization and injection are effecti ve in suppressing the maximum thermal hoop stress at the outer surface without the occurrence of the excess compressional stress at the inne r surface.