The temperature-induced variation in operating force of flow control valves may result in performance degradation or even jam faults of fuel metering unit(FMU), which significantly affects the safety of aircrafts. In ...The temperature-induced variation in operating force of flow control valves may result in performance degradation or even jam faults of fuel metering unit(FMU), which significantly affects the safety of aircrafts. In this work, an analytical modeling approach of temperature-sensitive operating-force of servo valve is proposed to investigate the temperature characteristics in varying temperature conditions. Considering the temperature effects, a new extended model of flow force is built and an analytical model of valve friction is also derived theoretically based on the dynamic clearance induced by thermal effects. The extremum condition of friction is obtained to analyze the characteristic-temperature points where jam faults occur easily. The numerical results show that flow force increases firstly and then decreases as temperature increases under a constant valve opening. The maximum friction of flow servo valve can be uniquely determined when the structural parameters and ambient temperature are given. The worst situation just happens at the characteristic-temperature points, which are linearly related to the axial temperature gradients of valve spool. Such evaluations may give an explanation for the temperature-induced jam faults of vulnerable valves and provide a reference for designers to determine a suitable workingtemperature range of valves in practice.展开更多
基金co-supported by the National Science and Technology Major Project of China (Nos. 2017-V-0011-0062,2017-V-0010-0060)National Natural Science Foundation of China (Nos. 51620105010,51875014 and 51575019)+1 种基金Natural Science Foundation of Beijing Municipality of China (No.L171003)Program 111 of China。
文摘The temperature-induced variation in operating force of flow control valves may result in performance degradation or even jam faults of fuel metering unit(FMU), which significantly affects the safety of aircrafts. In this work, an analytical modeling approach of temperature-sensitive operating-force of servo valve is proposed to investigate the temperature characteristics in varying temperature conditions. Considering the temperature effects, a new extended model of flow force is built and an analytical model of valve friction is also derived theoretically based on the dynamic clearance induced by thermal effects. The extremum condition of friction is obtained to analyze the characteristic-temperature points where jam faults occur easily. The numerical results show that flow force increases firstly and then decreases as temperature increases under a constant valve opening. The maximum friction of flow servo valve can be uniquely determined when the structural parameters and ambient temperature are given. The worst situation just happens at the characteristic-temperature points, which are linearly related to the axial temperature gradients of valve spool. Such evaluations may give an explanation for the temperature-induced jam faults of vulnerable valves and provide a reference for designers to determine a suitable workingtemperature range of valves in practice.
