Aerodynamic Characteristics Of Large Multi-Degree-of-Freedom Ornithopter

The large ornithopter inspired by the seagull was developed to imitate the graceful flight pattern of the seagull,with the intention of developing an aircraft with the high flight efficiency of the seagull.However,there are few existing twin-segment ornithopter similar to seagull,and most studies separate single segment ornithopter and double segment ornithopter,and do not systematically compare single segment ornithopter and double segment ornithopter of the same model.It is difficult to control the variables of different types of ornithopter due to the complex influence of vortices.At present,the research is mainly focused on theoretical research and data simulation,and there are few physical experiments.In order to solve the above problems,ANPRIO RL4,a simulation wind tunnel experiment platform of large ornithopter,was built based on large singlesegment and double-segment ornithopter,and the data were measured and some conclusions were drawn.The main contents are as follows:(1)In order to control variables for the same model,this thesis designed and assembled a large seagull-like flapping wing aircraft.The four-link flapping wing is designed to switch modes,so that the wing can switch between single and double freedom gull wings on the same large gull wing flapping aircraft.The outfield experiment verifies that the flapping wing aircraft can adapt to different environments well.(2)For the lack of experimental platform,in this thesis,a wind tunnel simulation platform ANIPRO RL4 was built.An experimental platform,ANIPRO RL4,which can simulate the flow state and sense the instantaneous moment of the ornithopter,was used to measure the experimental data under different ornithopter modes.Through the calibration and calibration of the sensor and the configuration of the data acquisition system,the lift,thrust and other aerodynamic characteristics measured under the same conditions of wind tunnel test can be achieved.The data accuracy is improved,and the wind tunnel test platform required by the traditional large ornithopter aircraft is solved,which has a series of problems such as large area and high cost.(3)For the lack of physical data,after completing the construction of the multi-degree of freedom flapping wing aircraft experimental prototype and simulated wind tunnel test platform,this thesis carries out the aerodynamic characteristics test of the flapping wing aircraft under two flapping wing modes,single segment and double segment,including lift test and thrust test.According to the test results,the performance of the two flapping wing modes is compared and analyzed.At the same time,the conjectures of single-segment wing and double-segment wing theoretical models will be verified by experiments.It provides a theoretical basis for the study of aerodynamic characteristics of multidegree of freedom ornithopter.This research can also provide the basis of strategy selection for the future bionic robots with automatic flight control.The results show that the thrust-to-weight ratio of the double wing ornithopter can not exceed that of the single wing ornithopter.But it has certain advantages in terms of lift.Taking into account lift and thrust during cruising,the single-segment wing appears to exhibit better aerodynamic characteristics than the two-segment wing.Therefore,this thesis guessed that this two-segment wing structure does not have significant advantages,which is inconsistent with the superb flight ability of birds in nature,indicating that the current twosegment wing model technology is not mature,and the body technology itself needs to be further improved.