Research On Rotating Blade Tip Clearance Signal Acquisition&High Speed Data Acquisition&Processing Technology

The tip clearance refers to the small distance between the high-speed rotating blade tip and the engine casing,which is an important parameter that affects the safety performance and energy conversion efficiency of the engines.Dynamic online tip clearance measurement technique is a key technology to perform safety monitoring,fault diagnosis and active clearance control of large rotating machinery,and one of the bottlenecks that restricts the development of the engines.In the process of on-line measurement,in addition to overcoming the harsh environmental impact,the overall system has the problem of high-speed mass data acquisition and transmission due to the high-speed rotation of the blade rotor.In order to meet the demand of dynamic online monitoring of tip clearance of high-speed rotating blades,this paper designs a whole system of acquisition and processing of tip clearance signal based on capacitive amplitude modulation method.Through the system software and hardware module design and debugging,this paper finally completed the prototype system development,and conducted simulation and acquisition and transmission test.The main work of this paper includes the following points:1.According to the characteristics of each method,combined with the harsh application conditions and the active control of clearances,the requirements for clearance measurement are introduced.The signal of tip clearance is measured by the capacitive amplitude modulation method.2.High-speed acquisition and processing system design.Aiming at the requirement of real-time on-line monitoring of blade tip clearance of aeroengine,a high-speed multi-channel acquisition and processing method of tip clearance signal based on FPGA is proposed.The method can choose two kinds of acquisition modes,complete data acquisition and key information acquisition,which can reduce the amount of data and reduce the overhead of the host computer.3.High-speed data cascade transmission design.Compared with the performance of various commonly used high-speed interface,combined with the project needs,the final choice and development of a PCI-based data cascade transmission scheme.Use DMA mode to transfer data to the host computer.4.According to the PC software requirements developed based on the QT platform for data reception and storage and data echo system.Software can achieve human-computer interaction,and data can be stored for display and other multi-taskparallel execution.5.The realization of the whole measurement acquisition system of the joint transfer,the completion of the acquisition and transmission simulation and experiments to achieve the function of the entire measurement acquisition system,and gives the measurement system measurement results.