Design Of Anti-vibration Vortex Probe With Acceleration And Research Of Two-phase Flow Measurement

Vortex flowmeter is a kind of flow meter based on the principle of vortex street.It is widely used in single-phase and two-phase flow measurement because of its simple structure,convenient maintenance and wide application.For the pipeline vibration condition in industrial field and the complex flow field environment of mist flow,a vortex probe with acceleration based on the technology of MEMS is designed.And the anti-vibration characteristics of flowmeter and the measurement characteristics of vortex street are studied in this paper.Specific research contents are as follows:1)Structural design and optimization of vortex probe.Based on the piezoelectric vortex probe structure,the acceleration vortex probe structure was designed,and the hydrodynamic analysis and finite element modal analysis are carried out.Based on the hydrodynamic analysis,the suitable width of the probe is determined to be 4-5 mm.Based on modal analysis,the natural frequencies of the probe do not affect the measurement of the vortex street.2)Design and optimization of vortex street detection system.Based on the analog design scheme,the hardware and the host computer of the detection system are designed and optimized.In the part of hardware design,sensor selection,signal acquisition circuit design,probe structure design and vortex street probe packaging were designed.In the aspect of sensor selection,a variety of analog accelerometers have been investigated,and KX220-1071 three-axis sensor has been selected according to the measurement requirements.In the aspect of signal acquisition circuit,PCB has been designed and optimized.In the aspect of probe structure,the appropriate size of probe support shell has been designed and optimized by simulation results,and the detailed process of probe packaging has been given.Finally,a signal acquisition system is designed based on Lab VIEW.3)From the perspective of pipeline vibration characteristics and vortex signal recognition,the anti-vibration characteristics of the accelerometer probe are analyzed.Firstly,based on the steady-state excitation method,the vibration characteristics of pipelines under different vibration accelerations and vibration frequencies are studied.The results show that the vibration energy of pipelines increases with the increase of vibration acceleration.Under different vibration frequencies,the vibration energy of the pipeline is a certain value,but it will increase abnormally at the resonance.And the on-line measurement method of pipeline natural frequency based on hammering is proposed to improve the measurement accuracy of vortex flowmeter.In addition,the transient excitation experiment shows that the anti vibration performance of vortex flowmeter is stable.4)Vortex Street experiment was designed to analyze the measurement characteristics of acceleration probe.Time-frequency analysis of the measured signal is carried out.The results show that the frequency characteristics of the acceleration probe are measured in orthogonal axes.The acceleration amplitude also reflects the characteristic information of the flow field force.And the characteristic information of the force is reflected by the acceleration amplitude.Finally,single-phase and two-phase calibration experiments are carried out.The results show that the linearity of the vortex measurement is ± 0.87% in single-phase,The error of the established mass flow model is within ± 5%,and the over-reading phenomenon is appeared in two-phase.