Investigation of jamming mechanisms in control valves under thermo–fluid–structure coupling conditions

Control valves are extensively deployed in downhole water injection systems. However, spool jamming frequently occurs, severely impairing field reliability and operational continuity. Such phenomena cannot be reproduced in surface tests, and no numerical model has previously been available to explain the underlying mechanism. To bridge this gap, a thermo–fluid–structure interaction model was developed to systematically analyze spool deformation and mechanical response, with particular emphasis on the evolution of spool–valve body contact stress, identified as the critical factor leading to jamming. The model's fidelity was validated against both experimental observations and spool deflection theoretical model. The root cause of spool jamming lies in the asymmetric pressure distribution induced by the lateral outlet, which generates a radial force bias. Under high pressure differentials, when the spool is eccentric with zero eccentric angle, its deformation transitions into a displacement-bending coupled mode, resulting in local geometric interference at the spool surface and outlet edge, and promoting multi-surface contact stresses that trigger jamming. To mitigate this risk, introducing an initial inclination angle of 180° under high-pressure conditions effectively offsets outlet-side deformation and suppresses contact stress. Furthermore, increasing the inclination and eccentric angles to 180° reduces the radial force by 37.9% and 22.4%, respectively. This study not only fills the numerical modeling gap for friction-induced jamming in control valves but also provides generalizable insights applicable to other valve systems where friction-induced jamming is a critical concern.