This study investigates the transient Fluid-Solid-Thermal (F-S-T) multi-physics coupling behavior of a direct-acting reversible check valve under extreme working conditions in a closed environment. The valve operates within a military system, functioning for gas addition and resisting explosive reactions, where its internal chamber experiences rapid transitions to ultra-high temperature (2000°C) and ultra-high pressure (800 MPa). Given the threat posed by such transient impingement to the structural strength of the pressure-bearing components, a detailed study is essential.
A coupled numerical simulation is employed, utilizing Ansys Fluent for Computational Fluid Dynamics (CFD) and Ansys Mechanical for Finite Element Analysis (FEA). A three-dimensional, compressible, Navier-Stokes model and F-S-T coupling governing equations are established to simulate the transient flow field and transient structural field.
Results indicate that the Impinging Flow Field (IFF) exhibits a highly unsteady state due to fluid inertia and aggregation-recoil effects, with local pressure peaks reaching 1590 MPa. The temperature field shows marked hysteresis relative to pressure and develops pronounced thermal stratification. The equivalent stress distribution closely follows the transient fluid pressure in the Impinging Structure Field (ISF), confirming strong F-S-T coupling. Although localized areas, particularly near the outlet region and specific inner walls, experience stresses exceeding the yield strength and enter the plastic stage, the overall valve structure remains intact, with stress levels staying within the material's ultimate bearing capacity.
This research demonstrates the viability of the adopted coupled simulation methodology for analyzing extreme transient events. The findings provide a valuable reference for the safety design and assessment of valves operating in similar extreme environments.