A novel valveless piezoelectric micropump with a bluff-body based on Coanda effect

Based on the Coanda effect, a novel valveless micropump is presented in this paper, the special bluff-body is utilized to enhance the Coanda effect and increase the net flow of the micropump. In order to reveal the influence of structural parameters on the performance of novel micropump, five micropump samples with different chamber radii (5 mm and 9 mm), aspect ratios (4 and 8) and channel angles (30° and 45°) are fabricated by silicon-based MEMS technology. On the conditions of the voltages (50–300 vpp) and excitation frequencies (25–125 Hz), the performance of the micropumps is studied experimentally in detail. As the voltage V = 300 vpp and the frequency f = 50 Hz, the maximum net flow and back pressure for the optimal sample can attain 4.84 ml/min and 1.75 kPa, respectively. Through numerical simulations, the efficiency of the micropumps with different aspect ratios L₁/d (3–9) are investigated as Reynolds number range from 300 to 1000 at the frequencies of 5–400 Hz. When the Reynolds number is constant, the pump efficiency has the optimal value with the increase of frequency, and the streamline diagrams indicate that this is related to the effects of the internal vortexes.