关键词: 频率检测, 随机共振, 外差式, 涡街信号, 侧接触, 粗糙度, 混合摩擦, 机械密封, 摩擦间隙

Abstract: The detection of vortex shedding frequency is a key technical problem of vortex flowmeter, and also a main subject of present research. The stochastic resonance characteristics of non-linear bistable system under the noise, single frequency and multi frequencies action are analyzed. With the combination of heterodyne power spectrum and stochastic resonance, a method based on heterodyne stochastic resonance to detect vortex shedding frequency is proposed. The theoretical analysis, numerical simulation and experimental results manifest that the SNR of vortex signal can be improved effectively and the vortex shedding frequency can be obtained accurately with the stochastic resonance applied to vortex signal. The method is feasible and effective in the detection of vortex shedding frequency. It is also a new method to improve the adaptability of vortex flowmeter in practical application and measure the low and weak vortex signal frequency accurately.

Key words: Frequency measurement, Heterodyne, Stochastic resonance, Vortex shedding signal, friction gap, Mechanical seal, mixed friction, roughness, shoulder-shoulder contact