Changlu Zhao

Scavenge flow analysis of opposed- piston two-stroke engine based on dynamic characteristics

Opposed-piston two-stroke engine has been proposed by Beijing Institute of Technology to improve power density and complete machine balance relative to conventional engines. In order to study opposed-piston two-stroke engine scavenging flow, a scavenging system was configured using a three-dimensional computational fluid dynamics model effectively coupled to experiments. The boundary conditions are obtained through one-dimensional working process simulation results and experiments. As the opposed-piston relative dynamic characteristics of opposed-piston two-stroke engine depend on different design and operating parameters including the opposed-piston motion phase difference and crank-connecting rod ratio, a numerical simulation program was built using MATLAB/Simulink to define opposed-piston motion profiles based on equivalent crank angle of opposed crank-connecting rod mechanism. The opposed-piston motion phase difference only affects scavenging timing while crank-connecting rod ratio affects scavenging timing and duration. Scavenging timing and duration are the main factors which affect scavenging performance. The results indicate that a match of opposed-piston motion phase difference and crank-connecting rod ratio has the potential to achieve high scavenging and trapping efficiency with a right flow in cylinder.

Research on integrate robust control Method for High-Power Variable-Speed Governor of Diesel Engine by loop-shaping theory

This paper present integrate robust control Method for High-power Variable-Speed Governor of Diesel Engine by loop-shaping theory. Diesel Engine working process and classical frequency control theory are combined to construct frequency restriction of engine speed; frequency compensator is utilized to improve the robustness of Multiplicative Perturbations and disturbance; loop-shaping method is applied to design the Variable-Speed controller of Diesel Engine. Simulation and Bench test result show that method has cutting off characteristic for high-frequency excitation from Engine Working Process and achieve lower sensitivity against the disturbances from load of road spectrum in low frequency range. It has performance robustness against Multiplicative Perturbations and disturbance. Compared with original controller, this method improves the control precision 83.6% and disturbance respond speed 22.7%.

Study on Robust Auto-MAP-Modify Method for High-Power Variable-Speed Governor of Diesel Engine by Extended State Observer

This paper present robust Auto-MAP-Modify method for High-power Variable-Speed Governor of Diesel Engine by extended state observer. Firstly the uncertain between MAP parameter and real parameter is defined as additive-Perturbations. Secondly the original controller is reconstructed as a dynamic controller for sensitivity and noises, meanwhile a static controller for Auto-MAP-Modify. The H∞ norm index is utilized to synthetically value robustness of the system. Finally Auto-MAP-Modify controller is designed by the Extended State Observer. Simulation and Bench test results show that the method is efficient for conquering the uncertain of MAP parameters. Compared with on board GA and Alopex algorithm, this method achieves rapider convergence rate and simpler structure.