This study investigates the aerodynamic performance of the NACA 633-421 airfoil and the effectiveness and feasibility of intermittent disturbance flow control methods on laminar separation bubbles(LSBs).It is found th...This study investigates the aerodynamic performance of the NACA 633-421 airfoil and the effectiveness and feasibility of intermittent disturbance flow control methods on laminar separation bubbles(LSBs).It is found that the average velocity and influence range of the synthetic jet actuator increase with the increasing of driving frequency and driving amplitude.LSB occurs at Re=1.0×10^(5),and ruptures atα=6°.But with intermittent disturbance control,the stall angle of attack(AoA)increases while significantly reducing drag.Research shows that although certain disturbance cannot fully recover from LSB stall,decreasing driving amplitude partially restores wing aerodynamic performance,more effectively than increasing driving amplitude.展开更多
An idea to make up the vibrating body of ultrasonic motor with anisotropic composite is proposed and a linear piezoelectric motor is developed in this paper. Relative problems such as actuating mechanism, resonant fre...An idea to make up the vibrating body of ultrasonic motor with anisotropic composite is proposed and a linear piezoelectric motor is developed in this paper. Relative problems such as actuating mechanism, resonant frequency are discussed theoretically. According to the feature that impulse exists between the elastic body of composite ultrasonic linear motor and the base, an impulse analysis is presented to calculate the motor′s friction driving force and frictional conversion efficiency. The impulse analysis essentially explains the reason why the ultrasonic motor has great driving force, and can be applied to analyze the non-linear ultrasonic motor.展开更多
文摘This study investigates the aerodynamic performance of the NACA 633-421 airfoil and the effectiveness and feasibility of intermittent disturbance flow control methods on laminar separation bubbles(LSBs).It is found that the average velocity and influence range of the synthetic jet actuator increase with the increasing of driving frequency and driving amplitude.LSB occurs at Re=1.0×10^(5),and ruptures atα=6°.But with intermittent disturbance control,the stall angle of attack(AoA)increases while significantly reducing drag.Research shows that although certain disturbance cannot fully recover from LSB stall,decreasing driving amplitude partially restores wing aerodynamic performance,more effectively than increasing driving amplitude.
文摘An idea to make up the vibrating body of ultrasonic motor with anisotropic composite is proposed and a linear piezoelectric motor is developed in this paper. Relative problems such as actuating mechanism, resonant frequency are discussed theoretically. According to the feature that impulse exists between the elastic body of composite ultrasonic linear motor and the base, an impulse analysis is presented to calculate the motor′s friction driving force and frictional conversion efficiency. The impulse analysis essentially explains the reason why the ultrasonic motor has great driving force, and can be applied to analyze the non-linear ultrasonic motor.
