Experimental studies were carried out on the performance of a new dual triangulate bluff body vortex shedders used for vortex flowmeter in aΦ50mmcircular pipe. Nine dual combinations on the basis of different sized triangulate bluff body geometries for a range of separations between 35 and 65mm were used in this work. The vortex shedding frequency was obtained on the basis of measured fluctuating pressure on the lateral side of the vortex shedder by piezoelectric press sensor. The performances of a number of dual triangulate combinations were described as follows. First, the pressures loss of these dual triangulate combinations are increased compared to that of single triangulate shedder. Second, the best linearity conditions of the new type vortex flowmeter were advanced. Third, the sensitivity of the detection of vortex shedding frequency of the new type vortex flowmeter was studied. A good linearity, regularity, sensitivity and range ability prototype of two triangulate shedders vortex flowmeter was developed.

The dynamical characteristic of a periodical fast switch valve was investigated theoretically and by experiments. It has been found that the pressure transient created by the periodic valve switching has different features with those of one closure. Except for the flow velocity and the closure speed, the switching frequency influences greatly the intensity of pressure transient. To gain the insight into the fluid dynamic performance inside the hydraulic system, the nonlinear resonance initiated by the interaction of succeeding pressure transients has to be taken into consideration. The numerical obtained results also agree well with the measured one. The used simulation model therefore will be useful in further developmental work.

In order to improve the noise immunity of vortex flowmeters, we have investigated the hydrodynamic vibration around the bluff body of the flowmeter. We used numerical approaches to visualize the time dependent vortex motion within the channel of the flowmeter, and experimental approaches to clarify the characteristic of the hydrodynamic vibration on the side faces of the prismatic bluff body. The results show that the hydrodynamic vibrations with 180

Having the advantages of no motion elements, high reliability, undemanding maintenance and good medium flexibility, the swirl meter has been widely used to measure the gas, liquid and steam in chemical, petroleum as well as processing industries. For the current one-piezoelectricpressure-sensor swirl meter, however, the measuring error caused by the interference pressure oscillation limits its application in the system where pressure is unsteady, or a noisemaker is nearby. In this paper, the fluid dynamic features inside the channel of the swirl meter are studied numerically and by experiment. The time dependent vortex motions as well as the hydrodynamic vibrations within the channel of the swirl meter are simulated using the CFD approaches of the RNG k-e model. The computed flow fields indicate that the eccentric motion of vortexes initiates an axisymmetric pressure oscillation within the vortex precession area of the swirl meter. The frequency of the oscillation shifts linearly with volume flow rates. Both the calculated and the measured results prove that the hydrodynamic vibrations on the arbitrary axisymmetric points are equal in amplitude and frequency but with a 180 degree phase difference. By installing differential pressure transducers on such the axisymmetric points, the signals of the vortex pressure oscillations are enhanced, while the interferential signals are suppressed, enabling the antiinterference performance and low-flowrate sensibility of the swirmeter to be effectively improved.

Computational Fluid Dynamics (CFD) simulations of cavitating flow through water hydraulic poppet valves were performed using advanced RNG k-epsilon turbulence model.Theflow was turbulent, incompressible and unsteady, for Reynolds numbers greater than 43000. The working fluid was water, and the structure of the valve was simplified as a two dimensional axisymmetric geometrical model. Flow field visualization was numerically achieved. The effects of inlet velocity, outlet pressuere, opening size as well as poppet angle on cavitation intensity in the poppet valve were numerically investigated. Experimental flow visualixation was conducted to capture cavtation images near the orifice in the poppet valve with 30

The structure and operating principle of micro valveless pump were investigated theoretically and experiinentally. The nlatheinatical model of pressure and flow rate within the inicro nozzle/diffuser was estsb lished to aralyze the effects of nozzle/diffuser parametels on the output flow rate of the inicro valveless pump. The experiments were carried out with different structural parameters, driving fi'equencies, vibration ampli tudes and stiffiness of the driving diaphragms. Effects of the structural parametels and driving conditiorks on the operation performance of the pump are discussed in detail. The work provides useful reference for structure op tiinization selection of the driving diaphragm of micro valveless pump.

In order to improve the engineering performance of a novel hydraulic shock generator, the fluid flow inside its complex passages is numerically investigated. The effects of the inlet flow velocity upon the turbulence intensity of the jet flow are analyzed. The calculated pressure loss is experimentally verified with the consideration of temperature determined viscosity shifting. The results are used as the reference in the further development of the hydraulic shock generator