Numerical investigation of the influence of nozzle geometrical parameters on thrust of synthetic jet underwater

The thrust characteristic and efficiency of synthetic jet underwater is easily affected by the geometrical parameters. In this paper, the influence of nozzle geometrical parameters on the thrust of synthetic jet underwater is investigated through numerical method. The geometrical parameters studied include nozzle diameter and nozzle height. The numerical method is validated using the experiment data. A mathematical model of the thrust is established. This model decomposes the thrust into three parts. By adjusting the weights of these parts, the dynamic characteristic of the thrust can be rebuilt. Using this method, the mechanism behind the thrust variation with nozzle geometrical parameters is analyzed. The variation of the thrust with the nozzle diameter is induced by the increase of the acceleration force and the decrease of the pressure force. When the nozzle diameter is small, the thrust is velocity dominated. While when diameter is large, the thrust is acceleration dominated. The thrust variation with nozzle height has two different patterns. The pressure force dominates the first pattern of thrust variation. And the acceleration force contributes more to the second pattern of thrust variation. The results in this paper can be used for the efficiency oriented optimal design of synthetic jet actuator underwater. (C) 2017 Elsevier B.V. All rights reserved.