Progress In Electromagnetics Research Symposium Proceedings, Marrakesh, Morocco, Mar. 20–23, 2011 1343
Theory and Experiment of the Valveless Piezoelectric Pump with
Rotatable Unsymmetrical Slopes
Jianhui Zhang1 , Qixiao Xia2 , Chunsheng Zhao1 , and Jiamei Jin1
1
Precision Driving Laboratory, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
2
College of Mechanical & Electronic Engineering, Beijing Union University, Beijing 100020, China
Abstract— With no relative motion at joint, no internal contamination, low manufacturing
cost, and easy to microminiaturization, the valveless piezoelectric pump has unrivaled application
in one-time use and miniaturization. However, the microminiaturization of the pump itself cannot
microminiaturize the whole system including the pump. Thus, this paper focuses on how to
integrate mixing and transport of piezoelectric liquid. Furthermore, the difficult and challenging
issues of the ratio of mixing fluid and composition control are also discussed. The valveless
piezoelectric pump with rotatable unsymmetrical slopes is put forward under this background.
Its major features are setting drive and transfer in one, also setting transfer and mixing in one.
Firstly, the design of the valveless piezoelectric pump with rotatable unsymmetrical slopes is
proposed and the one-way flow principle is analyzed. Then, the fluid mechanics model of the
valveless piezoelectric pump with rotatable unsymmetrical slopes is established. Meanwhile, the
flow numerical analysis and calculation of the pump cavity are done. Finally, the experiments
on relationship between the rotation angles of the slope and the flow rate and slope angles of
rotation and the two inlets flow ratio are conducted. The experimental results show that: the
maximum flow reaches 32.32 ml/min. The maximum relative error between the theoretical results
and the experimental ones is 14.59%. According to the curve indicating the rotating different
angles of rotatable unsymmetrical slopes to the flow ratio of the two inlets, the experimental
and theoretical maximum relative error is 3.75%. Thus, the principle feasibility of the valveless
piezoelectric pump with rotatable unsymmetrical slopes and the theory reliability are verified
and proven.
1. INTRODUCTION
By integrating the driving into the transmission, the valveless piezoelectric pump eliminates the
traditional mechanical transmission chain. What is more, this type of pump shares the features of
no relative motion at joint of drive part, no internal contamination caused by abrasive wear and
lubrication. So, it has the advantages: low processing costs, be easy to microminiaturize. This
valveless piezoelectric pump owns unrivaled application in one-time use and miniaturization [1–
7]. However, only miniature pump also does not necessarily in system miniaturization including
pump. Therefore, the research valveless piezoelectric pump is continually expanding functional integration, particularly in the integration of piezoelectric liquid mixing and transportation functions
and applications [8].
J. C. Rife, etc. proposed the piezoelectric devices designed for liquid mixture in 2000 [8]. The
essence is that piezoelectric vibrator drives obstacles in the mixing tank to produce vortex, to
achieve uniform mixing effect. However, it only can do liquid mixture and cannot transport.
However, no variability and non-regulatory of unsymmetrical slopes, cone block, and staggered
convex determine non-regulatory of ratio of mixture. Thus, these previous results only involves
simple mixing and transport integration, and does not take into account the liquid mixing ratio
and composition control needed transport.
Utilize underlying mechanisms of unsymmetrical slopes valveless piezoelectric pump working
principle, this paper provides a valveless piezoelectric pump with rotatable unsymmetrical slopes
(VPPRUS) which is easy to mixing and adjustable mixing ratio control.
Firstly, the design of the VPPRUS is proposed and the one-way flow principle is analyzed. Then,
the fluid mechanics model of the VPPRUS is established. Meanwhile, the flow numerical analysis
and calculation of the pump cavity are done. Finally, the experiments of pumping capacity are
conducted. Thus, the principle feasibility and the theory reliability are proven.
2. VALVELESS PIEZOELECTRIC PUMP WITH UNSYMMETRICAL SLOPES
Unsymmetrical slopes are the key component of the valveless piezoelectric pump with unsymmetrical slopes. They are arranged of several groups of slopes whose slope angles in the same direction
are equal, while unequal in the different direction (α1 6= α2 ). As shown in Figure 1.
PIERS Proceedings, Marrakesh, MOROCCO, March 20–23, 2011
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Figure 1: Unsymmetrical slopes.
Figure 2: Valveless piezoelectric pump with rotatable unsymmetrical slopes.
3. THE STRUCTURE OF THE VPPRUS
Figure 2 shows the structure of the VPPRUS. To facilitate the flowing of different mixing fluid,
two inlets and one outlet are designed; In order to achieve mixing ratio can be controlled, the
unsymmetrical slopes is rotatable.
When pump working, the two inlets are filled with two different fluids. Rotating unsymmetrical
slopes can change the flow resistance of each inflow and outflow, thereby achieving control of
the flow proportion of two inlets. Direct-flow is caused by one-way mechanism of fluid through the
unsymmetrical slopes. Meanwhile, the liquids mixed by the complex turbulence and vortex through
unsymmetrical slopes are transported to the outlet, and then the functions of simultaneous mixing
and delivery are completed.
Flow field and vortex in cavity will be change after the changing of geometrical position of the
rotatable unsymmetrical slopes. When the piezoelectric vibrator working, because the slopes are
rotated, the fluid can flow into pump chamber through two inlets with needed proportion, and can
mix with each other under the effect of rapid turbulent in cavity. The vortex is the driving force
of liquid mixing. The higher swirl intensity, the more complex form, the greater ability of mixing
and stir are.
4. THE PRINCIPLE OF THE VPPRUS
When pump working, driven by the alternating voltage, the center of the piezoelectric vibrator
warps upward and downward periodically caused by the peripheral fixing, so that the volume of the
pump chamber periodically changes. This change cycle T is the reciprocal of the driving frequency
f (T = 1/f ). The flow principles of suction and discharging cycle are indicated in Figure 3 and
Figure 4 respectively. To illustrate conveniently and simply, the piezoelectric vibrator model of
peripheral fixing and center warping is reduced to a type of piston in average change.
5. EXPERIMENTS
To verify the effectiveness of the theoretical analysis and simulation, this research develops the
pump for experimental verification. The design parameters of the pump chamber, the flow channel
and the rotatable unsymmetrical slopes are the same with that of the theoretical analysis. Table 1
shows the geometrical parameters and the drive parameters of the pump. Figure 5 is the photograph
of the VPPRUS for the experiments.
Figure 6 shows when the slope angle α1 = 30◦ , the theoretical and experimental relationship
curves between rotating different angles of the rotatable unsymmetrical slopes and the flow rates.
Progress In Electromagnetics Research Symposium Proceedings, Marrakesh, Morocco, Mar. 20–23, 2011 1345
Piezoelectric vibrator
Piezoelectric vibrator
Downward
Upward
Unsymmetrical slopes
Unsymmetrical slopes
Geometrical relationship
of unsymmetrical slopes
ÿ γ γ ÿ ββ
Geometrical relationship
of unsymmetrical slopes
γ β
ÿ αα2
ÿ αα
1
Figure 3: The flow principle of suction cycle.
α1
α2
Figure 4: The flow principle of discharging cycle.
(b) The pump chamber
(a) Experimental pump
(c) The rotatablc
unsymmetrical slopes
Figure 5: The photograph of the VPPRUS.
The data of the theoretical curve are from the simulation and calculation of last chapter. The results
show that: the data of experimental results and that of theoretical analysis are the same trend,
but the error also increases with the flow rate increases. The maximum experimental flow rate
QS = 32.32 ml/min, and the maximum theoretical flow rate QL = 37.31 ml/min. The maximum
relative error of the pump rate between experiment and theory is 14.59% when β = 9◦ .
Figure 7 shows when the slope angle α1 = 30◦ , the relationship curve of the ratio nL between the
theoretical flow rate of inlet 1 Q1L and the one of inlet 2 Q2L , the ratio nS between experimental
flow rate of inlet 1 Q1S and the one of inlet 2 Q2S , and rotating different angle β of rotatable
unsymmetrical slopes. The specific ratio is given from formula (1).
ni = Qi1 /Qi2
i = L, S
(1)
The results show that: the experimental ratio between the slopes rotation angle and the flow
rate of two inlets is only slightly lower than the theoretical value. From the curve between the
rotating different angles of the rotatable unsymmetrical slopes and the ratio between the inlet 1
and inlet 2, the experimental and the theoretical maximum relative error is 3.75%, when β = 14◦ .
A systematic error exists in the theoretical and experimental values. The roughness error of
the flow passage in pump chamber during theoretical calculation, and the multiple turbulence
error, etc, have not been considered in the numerical modeling. The fluid loss on the wall during
experimental measurement, the impurities in fluids, and other factors will all affect the accuracy of
the experiment.
See references [9–12], the non-regulatory changes of the unsymmetrical slopes, the tapered block
and the staggered convex determine non-regulatory issues of the mixing ratio. However, it is
the VPPRUS that overcomes the above-mentioned characteristics. To achieve the integration of
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PIERS Proceedings, Marrakesh, MOROCCO, March 20–23, 2011
Figure 6: The curve between the slope rotation angles and the flow rates.
Figure 7: The curve between the slope rotation angles and the flow rate ratios of two inlets.
piezoelectric liquid mixing and delivery, and make the overall system miniaturized possible. To
achieve setting drive and transfer in one, also setting transfer and mixing in one.
6. CONCLUSIONS
(1) This paper presents the VPPRUS. This pump achieves the integration of piezoelectric liquid
mixing and delivery, and makes the overall system miniaturized possible. To achieve setting
drive and transfer in one, also setting transfer and mixing in one.
(2) The working principle of the VPPRUS is analyzed, the formula for pump flow rate relationship
is established, and simulation and numerical methods are used to verify the above theories.
(3) The flow field and the flow rate of the VPPRUS are simulated, and the flow fields after the
inlet 1, inlet 2 and outlet are separated alone are simulated. In the role of the rotatable
unsymmetrical slopes, pressure in pump chamber is uneven, and the multiple turbulences are
resulted. The turbulences generated in inlet 1 and 2 are different, then the flow rates are also
different, and the proportional control of flow rate can achieve fluid mixing.
(4) The experimental pump is designed. The relationships between the slope rotation angles and
the flow rates, and the relationship between the slope rotation angles and the flow rate ration
of two inlets are all experimented. The results of slope rotation angle and flow rate show
that: the data of experimental results and that of theoretical analysis are the same trend,
but the error also increases with the flow rate increases. The maximum experimental flow
rate QS = 32.32 ml/min, and the maximum theoretical flow rate QL = 37.31 ml/min. The
maximum relative error of the pump rate between experiment and theory is 14.59% when
β = 9◦ .
The results of the slopes rotation angles and the flow rate ratios of two inlets show that: From
the curve between the rotating different angles of the rotatable unsymmetrical slopes and the ratio
between the inlet 1 and inlet 2, the experimental and the theoretical maximum relative error is
3.75%, when β = 14◦ . The experimental value is only slightly lower than the theoretical value.
ACKNOWLEDGMENT
This project is supported by National Natural Science Foundation of China (Grant No. 50775109),
the National Science Foundation of China important project (Grant No. 50735002) and National
Natural Science Foundation of China (Grant No. 51075201).
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