Optimization of Ultrasonic Acoustic Standing Wave Systems

Abstract

Ultrasonic acoustic standing wave systems find use in many industrial applications, such as sonochemical reactions, atomization of liquids, ultrasonic cleaning, and spray dry. In most applications, highest possible sound pressure levels are needed to achieve optimum results. Until now, the atomization of liquids is limited to fluids with low viscosity, as systems generating sufficient sound pressure for atomizing fluids with higher viscosities are often not marketable due to their low throughput or high costs. For the production of polymer or metal powders or the dispensing of adhesives, highest sound pressures should be achieved with systems in suitable size, with good efficiency and at low cost but without contamination of sonotrodes and reflectors by the dispersed media. An alternative to the use of more powerful transducers is increasing the intensity of the acoustic standing wave field by optimizing the boundary conditions of the acoustic field. In most existing standing wave systems a part of the radiating sound waves does not contribute to the process, as the waves spread into the wrong direction or wipe themselves out due to interference. In order to obtain maximum sound pressure amplitudes in the standing wave field, all waves should be trapped between the sonotrode and the reflector. In addition, the resonance condition should be met for all radiated waves. These conditions can be fulfilled by optimizing the shapes of sonotrode and resonator as well as the distance between them. This contribution reports on a model, which is able to simulate the sound field between a transducer surface and a reflector. Using a linear finite-element model, the boundary conditions of the standing wave system are optimized. Sound pressure levels of the standing wave field are calculated for different shapes of reflectors and boundary conditions like the distance between the transducer and the reflector. The simulation results are validated by sound-field measurements via refracto-vibrometry and a microphone. Finally, optimization guidelines for the generation of high-intensity acoustic standing wave fields are shown and verified by measurements.

Mechanism and Experiment Study of Non-Contact Ultrasonic Assisted Grinding

“…Figure 1 shows the schematic diagram of the non-contact ultrasonic grinding. The machining principle is that the piezoelectric ultrasonic transducer converts the high-frequency alternating current electrical signal into high-frequency ultrasonic vibration and transmits it to the amplitude transformer along the axis direction [27]. The amplitude transformer gathers energy to expand the amplitude, and then transmits the ultrasonic vibration to the working face of grinding tool [28,29].…”

Harmonic Response Analysis of Tank Design Effect on Ultrasonic Cleaning Process

“…FEA to develop the transducer and tank body impacting the industries can be exemplified as follows. The structural analysis [1,2], modal analysis [3][4][5][6], and harmonic response analysis (HRA) [6] were employed to investigate stress, deformation, and related results for optimizing the design of front masses for transducers to suit usages. Furthermore, since the transducer consists of front mass, piezoelectric (PZT) material, and back mass, the PZT is also studied and developed for many purposes [7].…”

Numerical simulation and experiment for the ultrasonic field characteristics of ultrasonic standing wave atomization

“…In addition to using a transducer with more power, the intensity of the acoustic standing wave field can be increased by optimizing the boundary conditions of the acoustic field. The radiation focusing of the ultrasonic field by a concave emitter is an effective mechanism to increase the ultrasonic intensity in the process of ultrasonic standing wave atomization [30]. By analyzing the ultrasonic coacervation performance of the shape of the transmitter, the performance of the concave spherical transmitter is obviously superior to that of the plane [31,32].…”