A Simplified Hydraulic Capacity-Sensitive Fluid Dynamics Numerical Model for Monitoring Aerospace Electro-Hydraulic Actuators

Detailed models are necessary to analyze individual components or subsystems when designing modern flight control systems. However, simpler models with sufficient accuracy are needed for preliminary layout, monitoring, diagnostics, or prognostic issues. Various simplified numerical solutions are available in the literature to simulate the fluid dynamic behaviors of a given valve geometry. These models typically calculate the differential pressure the valve regulates based on its spool opening and flow rate. In some specific applications, these models are unsuitable, requiring new simplified fluid dynamic models that calculate the flow rate delivered by the valve based on the spool displacement and differential pressure. This paper introduces a new synthetic fluid-dynamic valve model that considers the effects of spool position, hydraulic capacity, variable supply pressure, and leakage between the output ports that connect the valve to the motor element. Its advantages and disadvantages are evaluated by comparing it with other simplified numerical algorithms available in the literature, analyzing the corresponding fluid-dynamic characteristics, and comparing the behaviors simulating a typical flight control servomechanism.