A new design, not reported in the existing literature, combining features of ionic wind and mechanical vibration to induce appreciable airflow is developed. Its feasibility is demonstrated in a cooling system to enhance heat transfer. Ionic wind is generated using a thin, flexible plate as the emitting electrode and a heated, vertical plate as the collecting electrode. By placing a metal inductor close to the discharge electrode, an electrostatic field is formed. The electrode is attracted and thus moves toward the inductor owing to the electrostatic force created. To sustain periodic oscillation and produce large vibrational amplitudes, the inductor is grounded using current-limiting resistors. Vibrational characteristics are highly dependent on the corona voltage, resistance of the resistor, and position of the induction plate, which are examined in the experiments. It was found that the heat transfer enhancement is not improved at high corona voltages because the ionic wind overwhelms the mechanical effect of vibration. The vibrational effect becomes more prominent at low corona voltages with which the electrical field created by the corona discharge is not so intense. The maximum increase of heat transfer coefficient over that without vibration can be as large as 13.4% at the lowest corona voltage considered in the tests.
- TRANSFER ENHANCEMENT