Precision and Intelligence Laboratory, Tokyo Institute of Technology, Yokohama, Japan.
IEEE Trans Ultrason Ferroelectr Freq Control. 2010 Jan;57(1):253-61. doi: 10.1109/TUFFC.2010.1403.
An ultrasonic air pump that uses a traveling wave along a small air gap between a bending vibrator and a reflector is discussed. The authors investigate ultrasonic air pumps that make use of bending vibrators and reflectors and confirm that air can be induced to flow by generating an asymmetric acoustic standing wave along an air gap. In this paper, we proposed a novel ultrasonic air pump in which a traveling wave along an air gap induces acoustic streaming and achieves one-way airflow. Two new reflector configurations, stepped and tapered, were designed and used to generate traveling waves. To predict airflow generation, sound pressure distribution in the air gap was calculated by means of finite element analysis (FEA). As a preliminary step, 2 FEA models were compared: one piezoelectric-structure-acoustic model and one piezoelectric- structure-fluid model, which included the viscosity effect of the fluid. The sound pressure distribution in the air gap, including fluid viscosity, was calculated by the FEA because it is expected to be dominant and thus have a strong effect on the sound pressure field in such a thin fluid layer. Based on the FEA results of the stepped and the tapered reflectors, it was determined that acoustic traveling waves could propagate along the gaps. Experiments were carried out with the designed bending vibrator and the reflectors. The acoustic fields in the air gap were measured via a fiber optic probe, and it was determined that the sound pressure and the phase distribution tendencies corresponded well with the results computed by FEA. Through our experiments, one-way airflow generation, in the same direction of the traveling wave and with the maximum flow velocity of 5.6 cm/s, was achieved.
一种利用弯曲振子和反射器之间的小气隙中的行波的超声气泵进行了讨论。作者研究了利用弯曲振子和反射器的超声气泵，并证实可以通过在气隙中产生非对称的声波驻波来诱导空气流动。在本文中，我们提出了一种新颖的超声气泵，其中沿气隙的行波诱导声流并实现单向气流。设计了两种新的反射器结构，即台阶形和锥形，用于产生行波。为了预测气流的产生，通过有限元分析（FEA）计算了气隙中的声压分布。作为初步步骤，比较了 2 个 FEA 模型：一个压电结构-声学模型和一个包含流体粘性的压电结构-流体模型。由于预计粘性效应在如此薄的流体层中占主导地位并且对声压场有很强的影响，因此通过 FEA 计算了包括流体粘性在内的气隙中的声压分布。基于台阶形和锥形反射器的 FEA 结果，确定可以沿着气隙传播声行波。使用设计的弯曲振子和反射器进行了实验。通过光纤探头测量了气隙中的声场，并确定声压和相位分布趋势与 FEA 计算的结果非常吻合。通过我们的实验，实现了单向气流的产生，其方向与行波相同，最大流速为 5.6cm/s。
