Performance Study and Mathematical Model of Aerospace Geared Rotary Actuators

摘要

Geared Rotary Actuators are mechanical devices wildly used in the aerospace field to provide controlled motion to secondary flight control surfaces. Their use ranges from their application as powered hinges, when directly supporting the aerodynamic load forces in addition to the surface hinge moment, to actuators in linked mechanism where they provide the actuation torque and the aerodynamic load reaction is delegated to other load bearing equipment. In almost all cases, the GRAs are organized along the leading or trailing edge and are connected to each other via shafts and joints transferring the Power Drive Unit torque to the GRAs. From a mechanical stand point, the GRAs can be classified as epicyclical gear reducer and their internal mechanical arrangement can be wildly varied however the current industry state of the art focuses on two types. This paper will describe their configuration, the governing equations, and the mathematical model that can be used to characterize the GRAs. The focus will be on the speed ratio calculation, the efficiency of the unit as function of the single geared meshing efficiency, the sources of drag and the torque output capability.