Characteristic Research On Valve-less Piezoelectric Pump With Hemisphere-segment Bluff-body

Since the piezoelectric effect of piezoelectric materials was found, appeared a variety of newtype of piezoelectric devices, the piezoelectric pump as one of the fluid transmission device, With itsown many advantages are widely used in such areas as medical treatment and sanitation. Valve-lesspiezoelectric pump as an important branch of piezoelectric pump, with the difference between thevalve piezoelectric pump is, the use of special structure has no moving parts valve make fluiddynamic net flow, theoretically banned the lag problems caused by open of active valve body. Butcurrent valve-less piezoelectric pump always used the special structure of the flow tube on both sidesas the no-moving-part valves. Such kinds of pumps are difficult to miniaturize and low output flowrate problem always exist.In order to solve such problem, a hemisphere-segment bluff-body valve-less piezoelectric pumphas been put forward. The hemisphere-segment bluff-bodies are placed inside the pump chamber. Asthe fluid flows through the spherical surface and the round surface of HSBB there would emerge adifferent flow resistance. By using this, a net flow can be realized as the pump works. In order tomake a deep studying of such piezoelectric pump’s working principle and better apply it to medicaland fuel cell domain. Firstly, a theoretical analysis about the positive and negative flow resistance hasbeen made in this paper. Meanwhile finite element software is employed in simulating the flow fieldsof the pump. From the results, it can be found that the pump possesses a characteristic of the positiveand negative flow resistance is unequal, so the HSBB can be used as no-moving-part valves. Finallywe manufactured a sample pump and some series of HSBB, which the size of radius is different. Usedthese experimental devices we made some experiments on flow resistance and output flow rate. Theexperiment results show that with the pressure difference increase, the time difference decreasesbetween the positive and negative flow. We also found a relationship during the unit time the flowrate of the pump increases with the decreasing size of HSBB’s radius, which under the experimentalconditions of keeping the peak-to-peak voltage rate constant150V and changing the operating fre-quency. The maximum flow rate we obtained is121.4ml/min under the operating frequency in17Hzand the HSBB’s radius of4.0mm.