Thermal Effects on Aviation Hydraulic Systems: Degradation Mechanisms and Advanced Thermal Protection Strategies

Abstract Modern aviation hydraulic systems experience significant thermal challenges during high-intensity operations. Excessive heat accelerates seal degradation (aging, swelling, stress relaxation), hydraulic fluid deterioration (thermal decomposition, contamination, cavitation), and component failure, ultimately reducing system reliability. This review systematically analyzes the thermal effects on hydraulic systems, including the failure mechanisms of sealing materials, hydraulic fluids, and key components under extreme temperatures. Various thermal protection strategies are evaluated, including passive insulation (aerogels, ceramics), semi-active cooling (heat pipes, phase-change materials), and active cooling (nanofluid-enhanced heat exchangers, thermoelectric cooling systems). Furthermore, future advancements focus on the development of intelligent thermal management systems, multifunctional materials with adaptive thermal properties, and lightweight high-efficiency cooling structures to enhance system adaptability under extreme conditions. The integration of material innovations, real-time monitoring, and energy-efficient heat dissipation technologies will improve the thermal stability, operational efficiency, and long-term reliability of aerospace hydraulic systems, addressing the growing demands of modern aviation applications.