Due to the poor working conditions of an engine, its control system is prone to failure. If these faults cannot be treated in time, it will cause great loss of life and property. In order to improve the safety and reliability of an aero-engine, fault diagnosis, and optimization method of engine control system based on probabilistic neural network (PNN) and support vector machine (SVM) is proposed. Firstly, using the German 3 W piston engine as a control object, the fault diagnosis scheme is designed and introduced briefly. Then, the fault injection is performed to produce faults, and the data sample for engine fault diagnosis is established. Finally, the important parameters of PNN and SVM are optimized by particle swarm optimization (PSO), and the results are analyzed and compared. It shows that the engine fault diagnosis method based on PNN and SVM can effectively diagnose the common faults. Under the optimization of PSO, the accuracy of PNN and SVM results are significantly improved, the classification accuracy of PNN is up to 96.4%, and the accuracy of SVM is up to 98.8%, which improves the application of them in fault diagnosis technology of aero-piston engine control system.

A new measuring system for the engine tip clearance based on alternate current discharge is proposed in this article. Firstly, theoretical analysis and numerical simulation of the system, as well as the experiment of gas discharge are introduced to prove the feasibility of the method. Then a validation platform is built to study the effects of different probe materials and structures, as well as changes in temperature and humidity under atmospheric pressure on the system. Finally, the system calibration and tip clearance measurement are carried out. The results show that tungsten copper probe with planar structure is more suitable for measuring the tip clearance. When the tip clearance is between 0-6mm, the designed system has high measurement accuracy and its measurement error within 0.05mm. Compared with the traditional spark discharge method, the proposed method not only has the similar advantages, but also overcomes many defects, and has a broader application prospect.