Numerical Study Of Coupled Flowfield And Flight Envelop For Shipborne Helicopters

The analyses of flowfield and dynamic interface for the shipborne helicopter landing and the computation of Ship Helicopter Operational Limitation(SHOL) are challenging subjects in the field of helicopter aerodynamics and flight dynamics. On the one hand, a computational fluid dynamics(CFD) method for aerodynamic analysis of shipborne helicopter flowfield has been investigated in this paper. In order to simulate the flowfield of helicopter landing dynamic process, a new model, the so-called “Combination of Overset Mesh and Actuator Method”(COMAM), is also developed. On the other hand, a trim calculation model for shipborne helicopter which coupled with CFD method is established, and on the basis, the analysis of SHOL is carried out. The main research work is as followsAs precondition and background, the research purpose of this paper is described, and the research status of shipborne helicopter landing flowfield and SHOL is summarized. Besides, the difficulties and shortcomings in the current research are pointed out. In addition, the methods used in this paper are briefly presented.Firstly, two numerical methods based on actuator method and overset mesh method for predicting aerodynamic flow around ship have been developed, respectively. which take the flowfield characters of both ship and rotor, and several numerical examples are carried out to validate the two methods.Then, by applying the established flowfield prediction method, the deep research on ship flowfield is performed. The influences of upper structure and wind direction on the ship flowfield are emphatically analyzed. Meanwhile, calculations of the interface characteristics for shipborne helicopter coupled flowfield are carried out. Through comparing results of the two methods, some practical conclusions suitable for helicopterist are obtained.In order to achieve a continuous flowfield simulation for the helicopter dynamically landing on a ship, a new CFD model combining actuator method with overset mesh method is developed. By the method, several examples are calculated, and the effects focus on the hangar door opening or not and different landing manner on dynamic landing flowfield are analysis.In Chapter 5, a trim method for shipborne helicopter couples actuator technology with helicopter flight dynamics is established in this paper. On the basis, through introducing helicopter landing security criterion, a model that can be used to calculate the SHOL is developed, and by the model a SHOL for specific combination of ship and helicopter is calculated.Finally, the main work and innovation points of this thesis were summarized and the outlook of further study was presented.