Numerical Research Of Ship Airwake Flow Control And The Effect On Helicopter Shipboard Operations

The control of ship airwake and the effect on the helicopter shipboard landing are of great importance for improving the overall performance and expanding the scope of application of shipboard helicopters.A numerical methodology for the helicopter/ship coupling flowfield is established in this paper,studies the characteristics of the coupling flowfield above the flight deck and the aerodynamic characteristics of the rotor,and analyses the influences of different flow control methods on the shipboard flight.The main work is as follows:As the background of the work,the objective of the thesis and the current researches of the domestic and overseas about the helicopter/ship coupling flowfield and the flow control for ship airwake are firstly described,and then the shortcomings and difficulties in the current researches are pointed out.It also puts forward the research technical approach to be adopted in this paper.In the second chapter,based on the virtual rotor model(momentum source approach)and the real rotor model(moving overset mesh method),this paper develops two methods for numerical calculation of the helicopter/ship coupling flowfield,and selects the SFS2 ship model and the Georgia Tech rotor/fuselage interference model as the verification examples for the analysis of grid independence,isolated ship airwake and rotor aerodynamic interference.Applying the developed method,thia paper chooses the non-aviation ship(LPD-17)and the aviation ship(LHA)as the research objectives,analyzes the characteristics of the coupling flowfield above the flight deck of different types of ships,and conducts the qualitative and quantitative comparison of two numerical calculation methods.Furthermore,using the LPD-17 ship with more serious interference,the unsteady state characteristics of the ship airwake and the influence of that on the the aerodynamic characteristics of the rotor during the helicopter shipboard landing are carried out.In the fourth chapter,based on the aerodynamic modification of the ship superstructure,the research of the passive flow control for the ship airwake is carried out in this paper,and the influence of the spatial and temporal characteristics of the ship airwake on the overall performance and the unsteady disturbance of the rotor during the helicopter shipboard landing is analyzed for the understand of the flow control mechanism.Moreover,this paper also compares the the control effect of the flow control method on the coupled flowfield under the condition of different wind-over-deck(WOD).On the basis of the numerical results of the helicopter/ship coupling flowfield,a rotor trim method is introduced and analyzes the variation trend of rotor control quantities during the helicopter shipboard landing in the condition of different flight environment,different flight height and different WOD.Then,combined with flow control method,the velocity distribution at the plane of the rotor during the flight path is studied,and the effect of flow control method on the rotor performance and flight safety is analyzed.Finally,the main research work and innovation points of the thesis are summarized,and the outlook of further study is presented.