Aerodynamic Layout Optimization Design And Interference Characteristics Analysis Of Tilt-rotor Aircraft

The cruise speed of the helicopter of conventional configuration is greatly limited because of the forward blade shock and the backward blade stall when the helicopter works at high speed.As a new concept,the tilt-rotor aircraft can break through the limitation of helicopter flight speed and has the advantages of vertical take-off and high-speed cruise,so it can perform a variety of flight missions.However,there are some unique aerodynamic interference problems.Whether it is in the hovering mode,cruising mode or conversion mode,there are strong aerodynamic interference phenomena between rotor and fuselage.And it will greatly affect the aerodynamic characteristics of the fuselage and flight performance.So it has important academic significance and engineering application value to analyze the unsteady aerodynamic interference flow field and aerodynamic characteristics of the tilt-rotor aircraft in various flight modes and design the aerodynamic layout of the tilt-rotor aircraft based on the results of this analysis.In this paper,a new type of tilt-rotor aircraft was designed in detail,and its aerodynamic layout was studied in depth.At the same time,a momentum source correction method based on the dynamic airfoil database was proposed,and a set of numerical simulations methods for the calculation of the interference flow field and aerodynamic characteristics of the tilt-rotor aircraft in various flight modes were established in combination with the grid generation technology used for whole aircraft.Based on the established methods,the interference flow fields between rotor and fuselage in different flight modes were simulated,the aerodynamic interference laws were studied,the influences of the aerodynamic layout parameters were analyzed,and aerodynamic layout with high efficiency and low interference was designed.The research contents of this paper are as follows:In Chapter 1,the research background and significance of the paper were expounded,and the difficulties in the aerodynamic layout design of the tilt-rotor aircraft were analyzed.The research status of domestic and foreign researches on the analysis of the aerodynamic characteristics and the optimization of the aerodynamic layout of the tilt-rotor aircraft are described,and the difficulties and deficiencies are pointed out.The main research methods and technical approaches used in this paper were described.In Chapter 2,based on the unstructured grid hybrid technology,a set of high-precision numerical methods for the simulation of the interference flow field and the aerodynamic characteristics of the tiltrotor aircraft were established.In order to improve the simulation efficiency and simulation accuracy,a momentum source correction method based on dynamic airfoil database was proposed.The surface dynamic pressure of the ROBIN fuselage in forward flight and the normal force coefficient of the AH-1G rotor in forward flight were numerically simulated and compared with the experimental values,which verified the numerical simulation established in this paper was effective.In Chapter 3,according to the performance requirements,the design of the tilt rotor aircraft's configuration and aerodynamic layout were carried out.The wing,tail,control surface,hub and rotor were designed in detail,and the preliminary scheme for the aerodynamic layout of a new type of tilt rotor aircraft was completed.Finally,the weight distribution,component layout and 3D modeling of the aircraft were completed.In Chapter 4,based on the numerical simulation method of the whole aircraft interference flow field of tilt-rotor aircraft established in chapter 2 and the aerodynamic analysis method,the aerodynamic characteristics of the tilt-rotor aircraft designed in Chapter 3 in typical flight modes were calculated and compared with the characteristics of the isolated fuselage.The mechanisms of aerodynamic interference between tilt-rotor aircraft in typical flight modes were initially revealed.In Chapter 5,the interference flow fields of the tilt-rotor aircraft with different aerodynamic layout were simulated and analyzed.The influences of different aerodynamic layout parameters on the aerodynamic characteristics of the tilt-rotor aircraft were summarized.Then based on the optimization design method established in this paper,the aerodynamic performance of tilt-rotor aircraft with high efficiency and low interference was taken as the optimization target,and the rotor wing distance and wing sweep angle were selected as optimization variables.The aerodynamic layout was optimized and compared with the original aerodynamic characteristics of the tilt-rotor aircraft.The superiority of the optimized aerodynamic layout of the tilt-rotor aircraft was verified.In Chapter 6,the work of this paper was summarized.the characteristics and innovations of this article's research methods and research work were summarized.And the follow-up research work were explained.