Study of the mechanism of bird flight formation: upstream blade affecting the aerodynamic performance of downstream blade

In order to analyze the influence of the formation flight on the aerodynamic characteristics of the bird wings, two rows of upstream and downstream blades are set up to simulate the flying birds in the formation. In this study, DNS method was used to simulate the aerodynamic characteristics of blades.The FieldView 20 software was used for flow visualization and the Tecplot software for detailed data analysis.Through the study of aerodynamic principles, we can further explore the aerodynamic characteristics and causes of formation flight, which is of great significance for the research and design of aircraft or drone formations. By analyzing the aerodynamic performance of blades and its functional characteristics , the influence and mechanism of the formation flight were obtained in this study. The study shows that the tail vortex periodically grows and falls off the upstream blade to produce the vortex street, and the vortex street affects the near surface flow characteristics of downstream blade. Under the influence of the wake of the upstream blade, the change range of the low pressure area around the downstream blade increases, and a unidirectional vortex is produced in the front of the blade. This eddy current increases the area of the low pressure area and destroys the generation of the tail vortex, and increases lift and reduces drag.