Modified method of characteristics with maneuver overload impact analysis on water hammer effects

In response to the complex mechanisms of water hammer effects in aircraft fuel pipeline systems under maneuver overload conditions and the constraints of existing Method of Characteristics (MOC) analysis, this study proposes a modified MOC method (MMOC). By introducing an overload acceleration vector decomposition model within a non-inertial coordinate system, combined with dynamic friction correction and characteristic line grid integration, a generalized water hammer governing equation applicable to multi-directional overload coupling was derived. Utilizing an aircraft fuel pipeline system, the transient characteristics of water hammer under overload conditions were comparatively analyzed using both MMOC and CFD simulation methods. Results demonstrate that the MMOC accurately predicts water hammer pressure peaks under overload and effectively characterizes pressure fluctuation patterns at bends and valves. Axial overload significantly increases water hammer pressure amplitude while inducing radial flow field deflection and velocity variation. This study elucidates the dynamic coupling mechanism between overload acceleration and local flow field pressure gradients / velocity distributions, validates MMOC’s applicability for complex aviation pipeline water hammer calculations, and provides theoretical support for fluid-structure interaction dynamics analysis of fuel systems under maneuver overload conditions.