The Study Of Composite Flow Field Of The Helicopter Rotor And Ship Deck

Helicopters are increasingly loaded on the non-aviation ship to perform the tasks of transportation,supply,search and rescue because of their super low flight,unique hovering feature and efficient and flexible characteristic.Ship air wake flow field is the main zone for the helicopter landing on the ship.Ship air wake flow field has complex structure and large range of influence under the influence of the superstructure and the change of the wind direction.Previous theoretical analysis and practice flight shows the flow field structure above the deck has a great influence on the helicopter’s landing process.However,the existing literatures mostly study the deck flow field and helicopter flow field separately,and then analyze each flow field comprehensively, ignoring the interaction between them. This paper uses numerical simulation method to establish composite mode of the ship and rotor. The ship flow field, composite flow field with single rotor and multiple rotors are calculated numerically by using FLUENT software to study the composite flow field structure, turbulent kinetic energy distribution and aerodynamic characteristics of the rotor with different wind directions,rotor hovering position and rotor number.The numerical simulation method and solving scheme are introduced in this paper, and the rationality of the calculation model is discussed. The rationality of the calculation model and solving method are verifird by contrasting with the scaled-down ship model test results. On this basis,the flow field with different wind directions are solved(the wind against the bow, from fifteen degree to the starboard and from fifteen degree to the larboard). The composite model with single rotor is the rotor hovering separately on the deck apron A\B\C. The composite model with multiple rotors is the rotors hovering together on the deck apron A\B\C.The results show that: The ship flow field structure is different with different wind directions.When there are rotors hovering on the deck, the rotor blade tip vortexes mix with the ship deck vortexes,resulting in more complicated vortex structures in the deck flow field.The turbulence degree of the flow field behind the rotor increases due to the influence of vortex wake.The more front the position of the rotor,the greater the degree of mixing between the blade tip vortex and superstructure trailing vortex.As a kind of decision criteria, turbulent kinetic energy distribution can characterize the disorder degree of the flow field well.Mixings among vortexes intensify,high turbulent area increases and the rotors’lift capacities reduce with multiple rotors hovering together on the deck. Especially with cross wind directions,the lift capacities of the rear rotors decrease obviously. The results can provide theoretical support and reference for the helicopter’s safety when operating on the deck of the ship under different working conditions.