To the Calculation of a Closed Hydraulic EHD System
The purpose. To study the possibility of describing electrohydrodynamic processes in an EHD transducer with planeparallel grid electrodes, taking into account local hydraulic resistances.Methods. Using the method of integral relations and non-dimensionalization of variables that determine the force parameter of the Coulomb field and hydraulic resistance, on the one hand, and the value of unipolar charge formation, on the other, practically important relations for a cylindrical EHD system are obtained. By tabulating the dimensionless parameters characterizing the system, the effective modes of operation of a grid cylindrical EHD transducer are considered. The method of using the empirical relations of hydraulics made an assessment of the influence of local hydraulic resistance on the pressure characteristics of the system. Comparison of calculations with experimental model is carried out.Results. The modes of operation of a grid EHD transducer included in a closed hydraulic circuit are considered depending on dimensionless variables, on the one hand, expressing the level of charge injection of one of the electrodes, and, on the other hand, the power characteristic of the electric field and the magnitude of the hydraulic resistance of the external contour of a circular cross section . An engineering assessment is made of the influence of local hydraulic resistances, electrode grids with a given geometry, and sudden expansions and contractions of the working fluid flow on variable sections of a specific cylindrical structure of the EHD system on the pressure drop.Conclusion. For a fixed dimensionless parameter that characterizes the hydraulic resistance of the external circuit and the force effect of the interelectrode electric field, there are interval values of the parameter that determines charge injection, at which the efficiency of the grid EHD system is maximum. Even at low speeds, the resistance of the mesh electrodes significantly reduces the pressure created by the pump (up to 50%). At high hydraulic resistances corresponding to static pressure characteristics, the considered model satisfactorily describes the characteristics of the EHD system.