The uniaxial ring clamping force ultrasonic levitation device
|School||Shaanxi Normal University|
|Keywords||Ultrasonic levitation Annular clamping force Piezoelectric transducer|
Ultrasound suspension technology is the use of high intensity ultrasound standing wave field generated by the acoustic radiation force and gravity of the suspended sample equilibrium, the suspension sample to be stably suspended in the sound field of technology. Ultrasonic levitation technology major field of research or engineering aspects of the container processing and preparation of materials, state simulation of floor space, the experimental simulation of space conditions very unique application in the analysis of small samples or droplets. Ultrasonic levitation apparatus main exchange by the ultrasonic generator, the ultrasonic energy and acoustic reflection end is composed of three parts. The ultrasonic levitation device has uniaxial ultrasound suspension device and a three-axis ultrasonic levitation device two. Uniaxial ultrasonic levitation device structure is simple and convenient design, but poor suspension stability of suspension samples. Three shaft-type ultrasonic levitation means of the suspension sample to produce suspension force in three orthogonal directions in space, to thereby obtain a better suspension stability, but its high cost and complexity of the design and mode of operation is more developed, is not conducive to the application. Starting from the principles of the ultrasonic suspended analyze various types of ultrasonic levitation apparatus, studied and designed by changing the shape of the reflection end and the transmitting end, a set based on the uniaxial type having an annular gripping force ultrasonic levitation apparatus, improvement of the current the common uniaxial ultrasonic levitation device acoustic levitation force suspension sample stability problems. This study mainly include the following aspects: (1) based on ultrasound suspended theory, starting from the uniaxial ultrasound suspension device, improved acoustic emission surface and the shape of the reflecting surface, in the field of ultrasonic standing wave ring clamping force, improve ultrasonic suspension stability, simulation and experimental verification; (2) study of plane emission end - reflecting end, convex transmitting end - both reflecting end cavity characteristics of ultrasonic levitation device, using the finite element method both ultrasonic levitation device resonant cavity sound field and acoustic radiation force, and distribution of each resonator acoustic pressure and acoustic levitation force matlab simulation, compared suspended capacity and stability of the cavity. From the theoretical analysis of three physical factors that affect the resonant cavity acoustic radiation force; (3) under the assumption of the theory of one-dimensional design, the derivation of a half-wave time around the frequency equation and sandwich pressure to meet the needs of this study, according to the design of the frequency equation electric ceramic transducer (lead titanate); entire ultrasonic levitation device design and processing, experimental study. The results of this study show that: (1) the transmitter - reflective end uniaxial ultrasonic levitation device standing wave axisymmetric nature, satisfy the Helmholtz equation and its boundary conditions, the resonant cavity of the sound pressure and acoustic radiation force along the vertical plane straight direction showing the cyclical changes in the horizontal direction is constant, the gradient of the acoustic radiation force, can not produce. In the case of the same sample, the plane emission end - to - the reflection end resonator acoustic radiation force is reduced with the increase in the transmission side of the radius R, increases with the incident wave frequency f decreases, the vibration mode A more hours the greater the acoustic radiation force; (2) in the convex transmitter end - the reflective end uniaxial ultrasound suspension device resonant cavity, the sound field distribution also satisfies the Helmholtz equation and its boundary conditions, the resonant cavity sound pressure distribution of sound radiation the force not only in the vertical direction showing a periodic variation gradient of the acoustic radiation force is also generated in the horizontal direction. The suspended sample in such a resonant cavity in the annular clamping force field, the sample greatly reduce the possibility of departing from the suspension area; transmitting end - uniaxial type ultrasonic reflection end cavity of the suspension device (3) For a convex surface, the transmitter side Radius R must, height H2 of the convex height H1 and the reflecting side of the transmission side, and is equal to a half wavelength. In its maximum acoustic radiation pressure of the resonant cavity with the convex radius r of the transmission side, the incident wave frequency f and the change of the vibration mode A series of peak; (4) use of two cylindrical piezoelectric ceramic transducer planar transmission side - reflecting end ultrasonic levitation experiments, experimental results show that, in the ground under the conditions used such ultrasound suspension device can be suspended from the three samples, but its poor suspension stability in the horizontal direction, it is easily separated from the suspension area.