Research progress on flow control of propeller for low dynamic near-space vehicle

The low dynamic near-space vehicle, such as high-altitude solar-powered Unmanned Aerial Vehicle (UAV) and stratospheric airship, has the potential for sustained flight. It has important application values in military and civilian areas, such as continuous wide area early warning and reconnaissance, monitoring and observation, emergency response, and disaster relief. At present, due to the constraints of high-altitude rarefied atmosphere conditions and the energy consumption demand of variable altitude overnight, the low dynamic near-space vehicle faces to the problem of insufficient multi-point working efficiency of low Reynolds propellers. In recent years, with the reduction of energy consumption and improvement of reliability of control components, the potential of application of flow control in improving propeller efficiency has become prominent. This paper summarizes the research progress of flow control technologies for propellers of low dynamic near-space vehicles. Firstly, the aerodynamic analysis technology of low Reynolds propellers for near-space low dynamic vehicles is reviewed. The aerodynamic analysis basis required for propeller flow control is defined. Secondly, based on the principles of variable pitch and active/passive flow control, the research status of propeller passive control is analyzed, such as trailing edge deformation control and blade tip winglet control. Thirdly, the progress of plasma jet flow control of propeller is introduced. The research status and limitations of co-flow jet flow control are described, and then the current situation and potential of dual synthetic jet flow control are analyzed. Finally, the scientific problems of flow control for the low Reynolds propeller are summarized, and the feasible research directions are put forward.