Generation mechanism of the flow nonlinearity in single failure mode of a triplex redundancy servo valve

Aiming at the flow nonlinearity problem in the single failure mode of the electrical open circuit of the triplex redundancy servo valve, the mechanism analysis is carried out from the motion of the flapper of the fault pilot stage, and it is proposed that the cause of the flow nonlinearity is the contact between the flapper and the nozzle. Aiming at the characteristics of the flapper of the fault pilot stage, which is subjected to reverse motion by the feedback force, the equivalent reverse current method is proposed to simulate the flapper's contact action with the nozzle. The quantification method of flow nonlinearity is proposed based on the principle of the Douglas-Peukcer algorithm, and the flow nonlinearity is evaluated using the evaluation index related to the flow gain mutation point. Through the related simulation and experiment, the idea that the flow nonlinearity comes from the contact effect between the flapper and the nozzle is verified, and the effectiveness of using this quantification method on the flow nonlinearity problem of single failure mode is also proved.