Study On Aerodynamic Shape Optimization Of Dandelion-like Aircraft

Dandelion seeds rely on their feathered canopy structure to achieve seed diffusion and propagation through the lift generated by airflow.Drawing on their flight mechanism,biomimetic unmanned aerial vehicles with excellent hovering and slow descent capabilities can be designed.At present,there is relatively little research on the aerodynamic shape optimization of dandelion like aircraft,and most of its ideas are focused on the study of approximate rigid crown dandelion like aircraft models.There is no relevant research on the aerodynamic performance of flexible crown dandelion like aircraft.To determine the relevant design parameters of the aerodynamic shape of a dandelion like aircraft,this thesis establishes a dandelion like aircraft model for simulation analysis based on the measurement of dandelion seed parameters and the flight mechanism of dandelion seeds.Subsequently,an analysis was conducted on the main source of lift generation in the model,the feather like canopy,and the interaction between the forces acting on a single canopy under different parameters and the forces acting on multiple canopy was analyzed.Corresponding design parameters that would affect the flight performance of the dandelion like aircraft model were provided for subsequent analysis of the impact of single parameter changes.In the simulation analysis of the aerodynamic performance and wake vortex characteristics of the flexible crown model,this thesis uses a bidirectional fluid structure coupling simulation analysis method to obtain the corresponding crown shape variables,resistance coefficients,force conditions,and changes in wake vortex for different materials of the flexible crown model.And based on the tension angle generated by the deformation of the crown,a corresponding rigid crown model with tension angle was established to compare with the tension angle generated by the flexible crown.Then,simulation analysis was conducted on some models with tension angle and a set of rigid models with different tension angles,summarizing the control effect of crown angle on the flight attitude of dandelion like aircraft.In the analysis of the impact of single parameter changes on dandelion like aircraft,this article simulates and analyzes three sets of single parameter changes in models,which are divided into rigid and flexible crown situations.It explores the influence of various design parameters of dandelion like aircraft on the aerodynamic performance of the rigid crown model and flexible crown model,and compares the data in both cases.It was found that the trend of the influence of changes in design parameters on the aerodynamic performance of the model is basically consistent in both cases.In environments with low flow rates,the difference in aerodynamic performance between the two is not significant due to the small shape variables of the flexible crown model.The aerodynamic performance of the flexible crown model is slightly lower than that of the rigid crown model,and the structure of the vortex ring in the wake is also relatively similar;In environments with high flow rates,the flexible canopy model exhibits significant changes in shape variables and vortex ring structure,and also exhibits better aerodynamic performance than the rigid canopy model.After a series of simulation analysis,this article explores the impact of various design parameters changes on the aerodynamic performance of the flexible and rigid canopy models of dandelion like aircraft,and compares the obtained data in both cases,providing new ideas and data support for the subsequent design of dandelion like aircraft aerodynamic shapes.