Nonlinear Dynamics of Phased Array Levitators

Abstract

Acoustic levitation is a powerful method which enables objects to be levitated in mid-air using sound waves.
The introduction of phased array levitator (PAL) has expanded the capability of acoustic levitation. The PAL allowed the levitated objects to be manipulated more dynamically in a three-dimensional field and opened up avenues for new applications of acoustic levitation. Whilst the interest in the acoustic levitation is high, the dynamic behaviour of the levitated spherical particles has not been explored in-depth, and a linear stiffness model of remains standard in the field.

Therefore, this thesis aims to understand the underlying dynamics of a particle levitated in a PAL, and thereby improve the positioning performance of the particle. A single-axis PAL with two opposed emitting arrays was utilised for this thesis, and a numerical model was developed to predict the acoustic radiation force inside the levitator. A one-dimensional dynamic model was constructed using the numerical model to simulate the dynamic motion of particle in the PAL, and it was experimentally validated.
It was found that there are positioning inaccuracies in the PAL, and was found to affect the dynamic response of the system. The effects and implications of these inaccuracies were demonstrated via the development of numerical simulations, and calibration schemes were developed to minimise the effect of the deviation.

Both the numerical models and calibration methods in this thesis can be generalised to be applied to other forms of acoustic levitation, and the results presented here will lay the foundation for the current development of acoustic levitators. This case was confirmed by the application of the findings to the practical development of acoustophoretic volumetric display and will continue to aid the development of future application in the field of acoustic levitation.

Date of Award	24 Mar 2020
Original language	English
Awarding Institution	University of Bristol
Sponsors	Japanese Student Services Organization
Supervisor	Bruce W Drinkwater (Supervisor) & Tom L Hill (Supervisor)