Design Of High Precision Synchronous Acquisition System For Strain/Temperature Under Rotating Environment

In the process of research and development and testing of major rotating machinery equipment such as aeroengine and gas turbine,the structures such as turbine blades and roulette are easily damaged under the harsh environment of high-speed rotation,so real-time monitoring of strain and temperature has become an urgent need.However,it is difficult for traditional contact measurement to meet the requirements of such harsh working conditions.Therefore,it is very important to develop an efficient,accurate and reliable wireless acquisition system to realize the safe operation and performance optimization of high-speed rotating equipment.This paper studies and designs a multi-channel synchronous sampling system for strain and temperature under rotating environment.The main research contents are as follows:(1)The principle and measurement method of strain/temperature sensing based on resistance strain gauge and thermocouple are studied,and the influence of noise,temperature drift and other factors on measurement under high temperature rotation environment is discussed,and the corresponding improvement methods in the process of device selection and PCB design are put forward.(2)According to the measurement requirements,the overall scheme of the system and specific circuit performance indicators are proposed,and the hardware circuit and software system are designed in detail.Firstly,the hardware circuit of the acquisition system is designed and verified by simulation.The high-precision signal conditioning circuit,initial self-balancing circuit and bridge excitation circuit are modeled and analyzed and the parameters are calculated by using circuit simulation software TIN-Ti and LTspice.Then the wireless power supply scheme is modeled by SIMULINK to simulate its transmission efficiency and power.Finally,the system software is divided into lower computer and upper computer software design,and design the wireless data communication protocol based on Zigbee.(3)The test platform of the strain/temperature acquisition system under rotating environment was built,and the system was tested and verified.Under the rotating environment of 7000 RPM,the strand-bridge excitation achieves the load-carrying capacity of more than 70 m A while meeting the high precision.The maximum relative error of resistance matching accuracy of the program controlled bridge arm is 1.71% within the range of 120Ω～10kΩ.The wireless power supply function realizes the energy transmission of 15 W at the distance of 10 mm from the receiving and receiving coils.The highest efficiency was 69.87%,and the accuracy of standard strain/temperature signal was ±0.1%FS and ±0.2%FS,respectively.The above results prove that all the indexes meet the design expectations.