---

In this article, a special duct is introduced in which, inlet water jet initiates to oscillate after a short time and it causes the velocity and pressure to oscillate regularly. Considering that there is a linear relationship between the inlet jet velocity and its oscillations frequency, the flow rate can be calculated by measuring the pressure frequency. In order to study the flow field inside the current geometry of fluidic oscillator and also to find the optimum location for sensor to detect the pressure oscillation, the unsteady turbulent Navier-Stokes equations are solved by ANSYS CFX software. Having studied the grid independency, capability of K-ε and SST turbulence models for numerical simulation of unsteady flow inside the fluidic oscillator is considered. Then, according to the peak to average ratio (PAR) criterion, the qualities of pressure signals are compared at some points, to distinguish an optimum pressure sensor position. Afterwards, a prototype of fluidic oscillator flow meter is manufactured for the first time in Iran. Using this prototype and inserting the pressure and Piezoelectric sensor at the optimum point, the numerical simulation results are validated by the experimental data. Comparison between the numerical and experimental results shows that the SST model is more suitable for this flow simulation. Finally, by performing experiments in different flows, acquiring and processing pressure signals, the flow meter characteristic diagram (inlet jet oscillations frequency- inlet jet velocity) are extracted.

---

This article presents analytical and empirical studies of a micro-electromechanical package. This micro-electro-mechanical (MEMS) pressure sensor package contains of a printed circuit board (PCB), the capacitance LCD. First of all, mathematical modeling and computer simulation using software COMSOL software which is based on finite element method are presented to compute the sensitivity of the MEMS pressure sensor and output voltage output. It is worth noting that an Xducer resistor type is adopted to measure the diaphragm deflection. In addition to static and modal analyses of the sensor, the effects of geometric parameters on the voltage has also been studied. Simulation results show that by changing the size and position of the resistor and also the size and thickness of the diaphragm, sensor sensitivity can be changed. Then, with the construction and placement of components on printed circuit boards, the package has been prepared and tested in a laboratory. The experimental results of the package show that the error of the devised system in measuring the pressure is less than 0.5 percent. This pressure sensor package is capable of accurately measuring the pressure up to 6 bar in which all the empirical results are presented at the end of the study. The package can be designed according to the requirements of the petrochemical industry in measuring gas pressure of storage tanks and drums in FANAVARN petrochemical company.