Chaotic dynamics analysis of micro-pilot injection pressure in dual-fuel engines

High-pressure common-rail electronically controlled fuel injectors are key actuators that enable precise fuel injection in dual-fuel engines, their operating modes directly affects the fuel injection process and engine performance. Addressing the issue that injection pressure signals from dual-fuel engines with micro-pilot contain complex nonlinear dynamic information, but its evolution law remains unclear, this paper investigates the chaotic characteristics of injection pressure. By establishing a test bench for the high-pressure common-rail system of a dual-fuel engine, this study collected injector inlet pressure data under different rail pressures and operating modes. The chaotic characteristics were analyzed using methods such as phase space reconstruction, correlation dimension, Lyapunov exponents, and Kolmogorov entropy. Furthermore, through recurrence plots and recurrence quantification analysis, the study revealed the dynamic evolution patterns of the system's injection dynamics. The results show that the correlation dimension of the micro-pilot injection pressure in a dual-fuel engine ranges from [1.0451, 1.7583], with a maximum Lyapunov exponent ranging from [0.0115, 0.1174] and a Kolmogorov entropy ranging from [1.0694, 1.6351], indicating chaotic dynamic characteristics. The recurrence rate varied from 4.72% to 1.40% under different operating modes, indicating that the failure caused a significant change in the system's dynamical structure. The research framework provides a new perspective for the dynamic injection analysis of micro-pilot in dual-fuel engines based on nonlinear dynamical theory.