Thermal Properties of C919X EHAs Operating During Whole Flight Envelope

China's first large commercial aircraft C919 adopts a conventional central hydraulic system as the power of flight control actuation system. Meanwhile, the new type aircrafts A380 and B787 adopts more-electric technology, including power-by-wire actuators. It focuses more on security, power-weight ratio and clean sky performance. The next generation single channel airliner of COMAC, namely C919X, will consider power-by-wire actuators as an interesting option, such as active EHAs, which will be on operation during the whole flight time. Research is ongoing to reveal the cooling and heating demand of different EHA in different conditions. Hence, the first priority should be given to the methodology of controlling thermal equilibrium temperatures of EHA under entire flight envelope. This paper studied the thermal characteristics of EHA for C919X aileron. To start with, the thermal simulation model of variable speed constant displacement EHA and variable displacement variable speed EHA are established. By discussing two kinds of EHA under non-active heat- exchanging conditions, the operating points for heating or cooling and corresponding heat exchange power are achieved. Further, the structure, size, weight, operating mode and the differences of thermal characteristics between the two types EHA are illustrated. Based on 2- phase flow, a new kind of heat-pipe heat-exchanger which is integrated into EHA is developed. Lastly, the laboratory setup for measuring EHA’s inner and outer temperature is established. With the simulation of EHA of different surface and different flight envelope, we can address the thermal characteristics of different types EHA. Accordingly, more theories as well as technical skills for the design and manufacture of more-electric primary flight control actuation system for C919X are available.