A method for identifying the factors impacting the stability of the pressure difference control component in aero-engine fuel metering unit

Abstract

The pressure difference control component (PDCC) plays a crucial role in maintaining the metering flow stability of the aero-engine fuel metering unit(FMU). To ensure the stability of metering flow, a method for identifying factors impacting the stability of PDCC by analyzing the eigenvalue trajectories is proposed based on Lyapunov’s first method. The high-confidence nonlinear state space model of the PDCC is established, and its linear model is obtained by the Jacobian matrix. The original eigenvalue trajectories are extremely chaotic, which makes it difficult to analyze the stability influence law of design parameters. To address the issue, an eigenvalue classifier is designed according to the principle of minimum distance and position assignment criterion. 6 factors which have a key effect on the stability of PDCC, such as throttling orifice opening area of the pressurized locking valve(PLA), are effectively identified from 28 design parameters by this method. Based on the results, the mechanism of low-frequency pulsations in metering flow at low flowrate during FMU testing is revealed, and the low-frequency oscillation phenomenon at an unstable operating point(with the oscillation frequency of 28 Hz) is eliminated by adjusting the stability-impacting factors. The proposed method mechanistically reveals how design parameters govern PDCC stability, requiring only a state-space model formulation while eliminating complex model conversions. The approach provides direct guidance for stability-oriented PDCC design and actionable solutions for fault handling of metering flow fluctuation, demonstrating strong industrial applicability.