Fluid Devices by the Use of Electrohydrodynamic Effects of Water

When the high DC electric fields are applied to distilled water through needle electrodes, the jet flow with velocities up to 0.3 ms-1 is generated in bulk from the negative to positive electrodes. The flow direction and velocity can be modified by the design of electrodes and their arrangements. By controlling the flow patterns, new types of inkjet devices and liquid motor are developed. In inkjet devices, a set of electrodes consisting of short tube and needle is vertically placed in plastic tube and the distilled water so filled in the reservoir that the electrodes are completely immersed. The application of high voltages causes the vertical flow to produce a water column with free surface. The motor consists of vane wheel, cup, two sets of electrodes, and working fluid. For aqueous solutions of ethanol and glycerin, the angular velocity of motor is measured as a function of viscosity and conductivity. The high performance of motor is achieved by the solutions with viscosity of 0.85 ~ 1.7 m Pa•s and conductivity of 20 ~ 30 Sm-1. The EHD water jets have great potential in application to new fluid devices.