Optimization Of Vortex Flow Sensor Based On Numerical Simulation

As a kind of velocity-type flow sensor, vortex flow sensor works depend on the linearity of vortex shedding frequency and the velocity of fluid. The frequency signal, generated by vortex flow sensor, is proportion to velocity of fluid, and has nothing to do with the component, the density, the pressure and the temperature of the fluid. It has many merits such as high stability, low pressure loss, wide measurement range and simple structure. Vortex flow sensor is widely used in pipeline flow measurement.The determination of bluff body geometric parameter for traditional vortex flow sensor is based on the linearity of vortex shedding frequency and the velocity of fluid. It results in the low velocity frequency signal could not be measured by vortex flow sensor with traditional bluff body, which affects the usefulness of vortex flow sensor in low velocity measurement.As the wide use of digital meter, the linearity of vortex shedding frequency and velocity of fluid is not so important any more. The strength of vortex is the key for the usefulness of vortex flow sensor in low velocity measurement. Optimizing the bluff body shape of vortex flow sensor has important meaning for the usefulness of vortex flow sensor in low velocity measurement.The mainly research works of this thesis are as following.1. The fields in vortex flow sensor was simulated by computational fluid dynamic software FLUENT with two mathematic models. It was shown by simulation, water flow and air flow test that Realizable k-εmodel is the best model for vortex flow sensor. The upright axes component of fluid velocity, dynamic and static pressure signal are the characteristic parameters for simulation.2. By changing the rear body angle and parallel part length, the shape of bluff body was optimized. The best geometric parameters of bluff body both in water flow and air flow measurement has been obtained, which can bring the strongest vortex signal.3. By comparing the signal strength at different position after the bluff body, the best location of the pressure tap was researched. The best pressure tap locations both in water flow and air flow measurement were obtained.4. The result of simulation was verified by experiment on several bluff bodies in water flow and air flow, and the best bluff body shape for low velocity measurement was found.