About the Precision of the Liquid Doser of Slit Type with Waveformated Surfaces

Abstract

The device is used as an executive element of systems of biomedical assignment and can is used as the precision doser of liquid. The doser represents the slot-hole camera with waveformated surfaces. In contrast to the devices of peristaltic type with an elastic hose the considered device has no essential restrictions of downstream pressure and doesn't contaminate the transported liquid.

In work the current of an incompressible fluid in a flat slot of infinite width is considered. Two cases of creation of the waveformated movement in an operating slot are analyzed: the movement in the form of the running wave and the movement in the form of the fluctuations modulated by the running wave. In the latter case, it is possible to implement, irrespective of the required frequency of the running wave, rather big resonant fluctuations of elements of the piezoelectric transducer. It, in turn, allows to receive, at high resonance frequency, a small-size design of the piezoelectric transducer. At the same time in its operating slot there is a longitudinal movement of waves of resonant vibration, and the pressure differentials corresponding to them.

Flow of an incompressible liquid in a flat gap is considered. The equation of Reynolds is used for the description of driving of the fluid environment, the decision concerning pressure is brought to analytical expressions or quadratures. The lubricant flow rate and difference of pressure is defined on working length in an explicit form. Increase in pressure and expense in thin layers of an incompressible fluid with growth of amplitude and frequency of wave movements is shown. It is noted that it is slightly less magnitude of pressure differentials and expenses in layers with the fluctuations modulated by the running wave, than in layers with the running wave. These results are assessment from above and can be significantly less at emergence of cavitation in liquid.

The analytical results received in work allowed to consider also questions of ensuring accuracy of operation of the doser in the different modes of its operation. It is shown that the largest accuracy of dispensing is reached when transporting liquid from a vessel in a vessel with identical pressure or in case of overlapping of a gap crests of a running wave.