Papers by Author: Sheng Jun Shi

Abstract: A D2Q9 thermal lattice Boltzmann model is applied to investigate the flow in a differentially heated cavity. The paper is intended to analysis the physics of heat and mass transfer in a closure cavity filled with air. For three Rayleigh numbers Ra, the aspect ratio K are varied from 1 to 10. Results of validation indicate this algorithm is reliable and easy for implementation. It can be found that the circulation rate of heat driven flow get lower when the K get higher. Also, the Nusselt number Nu tends to be approximated to 1 when K is higher than a critical value, which is depended on the value of Ra.

Abstract: A rotary ultrasonic motor using longitudinal and bending vibration modes is proposed in this study. The proposed motor contains two exponential shape horns located on two ends, and the end tips of the horns are used as the driving feet. Two groups of PZT elements (Longitudinal PZT and Bending PZT) are clamped in the middle of the motor by a double head flange bolt to excite the longitudinal vibration mode and bending vibration mode of the motor, respectively. By the composing of the longitudinal and bending vibration modes, elliptical trajectory vibrations can be generated on the end tips of the horns, which have the same rotation directions and can driving the rotor together by frictional force. After the introducing of the working principle, modal analysis is developed to tune the resonant frequencies of the longitudinal and bending vibration modes to be close with each other. At last, transient analysis is developed to gain the vibration characteristics of the motor, and the gained elliptical trajectory motions of particles on the driving parts verify the feasibility of the proposed design.

Abstract: A double driving feet linear ultrasonic motor using longitudinal vibration transducer is proposed in this paper. The stator of proposed motor contains a horizontal transducer and two vertical transducers. The horizontal transducer includes two exponential shape horns located at the leading ends, and each vertical transducer contains one exponential shape horn. The horns intersected at the tip ends where located the driving feet. The horizontal and vertical vibrations of driving feet are generated by the longitudinal vibrations of horizontal and vertical transducers, respectively. Longitudinal vibrations are superimposed in the stator and generated elliptical motions at the driving feet. The two vibration modals of stator are gained with FEM, and the resonant frequencies of two vibration modals are degenerated by adjusting the structural parameters. Transient analysis of piezoelectric coupling states the good and strong elliptical motions of driving feet, and verifies the theoretical feasibility of proposed motor.

Abstract: A cylindrical standing wave ultrasonic motor using cantilever type bending transducer is proposed in this paper. There are four cantilevers outside the cylinder, and four PZT ceramics are set on each end surface of cantilevers. The bending mode of cylinder is excited by the bending vibration of transducers. Thus, a linear simple harmonic motion is achieved at the particle on the tooth. The working principle of proposed motor is analyzed. The cylinder and transducer are designed with FEM. The bending vibration modals of transducer and cylinder are degenerated. The transient analysis is developed to gain the vibration characteristics of stator, and the results indicate the proposed motor has potential good output characteristics. The results of this paper verify the theoretical feasibility and provide instructions for the development of proposed motor.

Abstract: A square-type rotary ultrasonic stator using longitudinal vibration transducers is proposed. The proposed stator contains four longitudinal vibration transducers, which are located in square-type. Every longitudinal transducer includes two exponential shape horns located on each end. And the horns of adjacent transducers intersected at tip ends where located the driving feet. The longitudinal vibrations of transducers are excited by the longitudinal vibrations of PZT ceramics. Longitudinal vibrations of adjacent transducers are superimposed in the driving foot and generated elliptical trajectory. The actuating mechanism is analyzed, and the motion trajectories of driving feet are deduced. The stator is designed and analyzed by using FEM method. The vibration characteristic of stator is gained by transient analysis. Results indicate that the motion trajectories of the four driving feet have good consistency, and the proposed motor has potential good output characteristics. The results of this paper verify the theoretical feasibility and provide instructions for the development of proposed stator.

Abstract: To obtain large mechanical output power, a ring type standing wave ultrasonic motor using cantilever type bending transducer is proposed. There is a cantilever on one side of the ring, and four PZT ceramics are set on each end surface of the cantilever. The bending mode of ring is excited by the bending vibration of cantilever transducer. Thus, linear simple harmonic motions are achieved at the particles on the teeth. The working principle of proposed motor is analyzed. The ring and transducer are designed with FEM. The bending vibration modals of transducer and ring are degenerated, and the motion trajectories of nodes on the teeth are analyzed. The analysis results indicate that a standing wave is excited in the ring by the bending vibration of transducer, and the proposed motor has potential good output characteristics. The results of this paper verify the theoretical feasibility and provide instructions for the development of proposed motor.

Abstract: A cylindrical type traveling wave ultrasonic motor using orthogonal longitudinal composite transducer is proposed. The composite transducer contains two longitudinal transducers, which are located orthogonal to each other. Each longitudinal transducer includes one exponential horn located on leading end, and the horns insect with each other at tip ends. The composite transducer is attached to the cylinder on its outer surface to excite two degenerate flexural vibration modes spatially and temporally orthogonal to each other in the cylinder. Thus, a flexural traveling wave in the cylinder could be excited. The working principle of proposed motor is analyzed. The stator is designed with FEM. The vibration modals of stator are degenerated. Transient analysis is developed to gain the vibration characteristics of stator, and results indicate that the motion trajectories of nodes on the teeth are ellipses. The results of this paper verify the theoretical feasibility and provide instructions for the development of proposed motor.

Abstract: To take advantage of merits of higher output-power and efficiency of bolt-clamped transducer, a ring type traveling wave ultrasonic motor using cantilever type composite transducer is proposed in this paper. In this new design, two cantilevers are set for the coupling between ring and transducer. Two standing bending waves (with phase difference of π/2 on time and space, respectively) are generated in the ring by the bending-longitudinal vibrations of transducer. Thus, a flexural traveling wave can be excited. The working principle of proposed motor is analyzed. The stator is designed and analyzed with FEM, and the motion trajectories of nodes on the teeth are analyzed. The results of transient analysis verify the theoretical feasibility of proposed design. The results of this paper could guide the development of this new type of motor.

Abstract: A cylindrical type traveling wave ultrasonic motor using composite transducer is proposed in this paper. A composite transducer is attached to the cylinder on its outer surface to excite two degenerate flexural vibration modes spatially and temporally orthogonal to each other in the cylinder. In this new design, a single transducer can excite the flexural traveling wave in the cylinder. Thus, an elliptical motion is achieved at the particle on the tooth. And the driving force is the frictional force between rotor and teeth. The working principle of proposed motor is analyzed. The cylinder and transducer are designed with FEM. The sensitive parameters of resonance frequencies of transducer and cylinder are gained with modal analysis. The resonance frequencies of two vibration modals of stator are degenerated, and the motion trajectories of nodes on the teeth are analyzed. The result of transient analysis shows that the trajectory of node on the tooth is nearly an ellipse. The results of this paper could guide the development of this new type of motor.