Thermal Modelling of a Flight-Critical Electrohydrostatic Actuator

The use of electric actuators, such as electro-hydrostatic actuators (EHA), for moving flight control surfaces is an integral part of the more-electric aircraft (MEA) concept to replace inefficient, centralized hydraulic systems with power-on-demand electrical systems. Removing the centralized hydraulic system will, however, eliminate an effective heat transfer network, thus resulting in an aircraft with less overall heat to reject but with localized “hot spots.” Under the Air Force MEA Thermal Management program, Northrop Grumman is assessing the cooling requirements for an MEA version of the F/A-18 aircraft through detailed thermal modelling and computer simulation. Lumped-parameter EHA thermal models have been developed to characterize component heat transfer within their operating environments using realistic actuator duty cycles generated from six-degree-of-freedom (6-DOF) aircraft simulation. This paper summarizes the thermal modelling effort and its utility in designing a thermal control solution for a flight-critical stabilator EHA.