Research On Real-time Fault Detection Technology And System For Liquid Rocket Engine Turbopump

Research on health monitoring technology and system for liquid-propellant rocket engine (LRE) can establish a solid theory and application basis for enhancing the reliability and safety of space vehicles thruster system as well as reducing the costs. Turbopump is the important component of LRE to transport propellant. Because of its execrable working circumstance, turbopump has a higher fault probability than other components. What's more, its faults develop very fast, and severely endanger LRE safety. On the other hand, supported by the real-time fault detection technology, the turbopump fault detection system can detect faults in time. Under the help of engine controller, this system can mitigate turbopump faults development tendency and diminish their effect on engine etc. Thus, the research on real-time fault detection technology and system for turbopump is very significative in LRE health monitoring.Supported by the projects"Research on health monitoring and fault diagnosis technology for liquid rocket engines"and"Research on novelty detection theory and approaches for health monitoring of complicated mechanism", which belong to national high technology research and development program of China (NHTRDPC, 863 Program) and national natural science foundation of China (NSFC) respectively, this dissertation carried out the research on real-time fault detection technology and system for LRE turbopump. The main contents and innovative work can be summarized as follows:1. The research course and current situation of LRE health monitoring technology and system were investigated in detail. Based on this, their developing trend was dissertated, and the main problems that need to be resolved immediately for China LRE turbopump health monitoring were pointed out.2. After turbopump basic structure and working circumstance were discussed, the qualitative analysis of its vibration characteristics, fault modes and mechanism were carried out. Then the turbopump vibration signal features law of its main fault modes was dug out.3. Based on the vibration signal features law, the quantitative analysis method for turbopump fault sensitivity was brought forward, and the linear correlation, stability and fault sensitivity of signals time domain and frequency domain features were studied. Then the corresponding tubopump vibration signal features were selected and extracted.4. To detect the turbopump faults real time, the turbopump real-time fault detection theory and methods were studied in detail. Then the gradient descent approach for training thresholds band coefficients and the strategy for abscising influence that abnormal vibration data act on thresholds were put forward. At the same time, based on the 3 time domain fault features such as signals mean square root, clearance factor and kurtosis, the red-line alarm algorithm, adaptive threshold algorithm and adaptive correlation algorithm were improved, and the multi-features red-line alarm algorithm (MRLA), multi-features adaptive threshold algorithm (MATA) and improved adaptive correlation threshold algorithm (IACA) were brought forth correspondingly.Validated by the rotor platform online data and LRE post-test data, these improved 3 algorithms can detect the turbopump faults effectively and real time. Compared with current redline cutoff system, their fault detection time is notably shorted.5. The pivotal technology of real-time fault detection and high speed data acquisition & logger were studied. And the method of using MRLA, MATA and IACA to synthetically decide turbopump state was put forth. Then multiple time domain and frequency domain signal processing methods were studied. Based on these research results, the turbpump fault detection system (TP-FDS) was designed and constructed. This system includes the real-time fault detection subsystem (RT-FDS) and post-test data analysis subsystem (PT-DAS) etc.Validated by the rotor platform online data, LRE post-test data and field firing test online data, RT-FDS can detect the turbopump fault effectively and real time. Compared with current redline cutoff system, it can detect faults earlier. PT-DAS can further analyze and confirm turbopump state.In a summary, the real-time fault detection technology and system for LRE turbopump were studied thoroughly. The turbopump vibration characteristics, fault modes and mechanism were analyzed. Then the linear correlation, stability and fault sensitivity of turbopump vibration signal time domain and frequency domain features were researched, and signal features were selected and extracted. Subsequently, 3 real-time algorithms to detect turbopump faults were brought up. Finally, TP-FDS was designed and constructed. Validated by RLE test data, this system can be successfully applied to real-time online detection and post-test analysis for turbopump state. It is believed that these conclusions provide feasible theories and realization approaches for turbopump real-time fault detection and post-test state analysis, which are worthy of academic reference and project application.