Thermohydraulic Modeling of An Electro-Hydraulic Servo Actuator on Damped Mode

Abstract

Hydraulically powered flight control systems are widely used in aviation, especially for commercial aircraft, which require significant forces from system actuators to control the applicable surfaces as demanded. These systems are being studied and are evolving to become smaller, lighter, and more efficient. These improvements bring several advantages, such as payload increase and drag reduction. However, as these systems are optimized, and their dimensions are reduced, the thermal effects of fluid flow become more relevant. Especially when the working fluid passes through small orifices, excessive heat can eventually compromise the equipment's performance and damage its internal subcomponents. When we analyze the damped mode operation of actuation systems presented on some commercial aircraft, these restrictions become even more relevant – knowing that the damping orifice diameter can be significantly reduced to provide the desired performance for the operation. Therefore, the main goal of this study is to analyze and evaluate the thermal impact on an Electro-Hydraulic Servo Actuator (EHSA) while in damped mode operation, contributing to the industry and the literature in this kind of assessment. Through the research presented, it's possible to estimate the temperature of the system's components and, consequently, avoid malfunctions caused by overheating. Furthermore, developing a model allows the simulation of various environmental conditions, reducing rig costs or in-flight tests. The modeling approach was conducted on the MATLAB/Simulink platform. It was based on two main points that improved model comprehension during its development and minimized errors: the building blocks philosophy of segregating each component's influence and model, and the continuous validation of the model through a comparison with a physics-integrated software (AMESim).