In the hardware-in-the-loop (HIL) simulation of the fuel control unit (FCU) for aero-engines, the back pressure has a great impact on the metered fuel, thus influencing the confidence of simulation.During the practical working process of an aero-engine, the back pressure of FCU is influenced by the combined effect of the pressure of combustion chamber, the resistance of spray nozzles, and the resistance of the distribution valve. There is a need to study the mimicking technique of FCU back pressure. This paper models the fuel system of an aero engine so as to reveal the impact of FCU back pressure on the metered fuel and come up with a scheme to calculate the equivalent FCU back pressure.After analyzing the requirements for mimicking the pressure, an automatic regulating facility is designed to adjust the FCU back pressure in real time. Finally, experiments are carried out to verify its performance.Results show that the mimicking technique of back pressure is well suited for application in HIL simulation. It is able to increase the confidence of simulation and provide guidance to the implementation of the mimicking of FCU back pressure.Hardware-in-the-loop (HIL) simulation enables the operation and testing of actual components of a system along with virtual computer-based simulation models of the rest of the system in real time. 1,2 In this way, quality of testing is enhanced, thus shortening the design cycle and improving the reliability of the tested components.Fuel control unit is a fuel-metering device that regulates the fuel flow to the engine in accordance with the pilot's demand, ambient environmental conditions, and other related factors. It is a crucial part of engine control system. Usage of HIL simulation for testing aero-engine FCU has been reported in several researches for different purposes. 4 have investigated the complex interaction between the FCU hardware and overall aircraft performance, while Karpenko and Sepehri 5 objectively tested novel fault tolerant control and diagnostics algorithms for fluid power actuators. Principles of the fuel control are presented by Tudosie, 6 among which the type with constant fuel differential pressure and Simulation,
