عنوان مقاله [English]
In the present study the dynamic behavior of a piezoelectric flow micro sensor based on vortex-induced vibrations (VIV) is investigated. This sensor is made by a cantilever beam, piezoelectric layer and a cylinder at free end which is used to measure the fluid velocity. The proposed VIV sensors have nonlinear dynamic behavior for different flow velocities therefore in designing VIV micro sensors obtaining linear operational working range is an important parameter. In this paper the dynamic behavior of micro flow sensors based on the modified couple stress theory (MCST) is investigated and linear operational working span is derived. The coupled governing equations of silicon based and piezoelectric layer cantilever beam, gauss electric and Van der pol equation are derived. Utilizing the derived equations the dynamic behavior of the micro sensor on the basis of parameters such as damping coefficient, cantilever beam length, material length scale parameter and tip cylinder mass is analyzed. The operational work range of the micro sensor, the acceptable linear behavior domain and error of linear behavior assumption of the device is investigated. According to the results the maximum linearization error is 3.5%. In addition to that reduction in cantilever beam length and tip cylinder mass increase the operational working range of the micro sensor. Analyzing the effect of damping coefficient on the dynamic behavior of micro flow sensor show that increasing the damping coefficient decreases the beam deflection and output voltage, but has no effect on the operational working span of the system and in order to obtain precise output from this sensor the damping coefficient must be reduced. Findings indicate that parameters which make the device behave stiffer such as reduction in beam length or tip cylinder mass or considering non-classical stresses gives a wider acceptable voltage range at higher flow velocities for the micro sensor.