Study On Airflow Field Characteristic Of Helicopter Deck Of The Littoral Combat Ship

In order to study the characteristics of flow field on the helicopter deck for the littoral combat ship(LCS),the FLUENT software was used to conduct numerical simulation of the "independent class" littoral combat ship(LCS-2).For analyzing the characteristics of the flow field of the helicopter deck of the LCS-2,the calculated results were compared with the numerical simulation results and wind tunnel data of the isolated simplified frigate ship SFS2?The calculation results show that the airflow field of the helicopter landing platform of the LCS-2 changing with the wind speed to meet Renault autocollimation principle,and the the most suitable wind direction Angle for the aircraft of the LCS-2 take-off and landing mission of the range is 0° and 30°,the flow field of the LCS-2 is more suitable for helicopter landing than SFS2 in most areas of the deck.Large-sized flight deck and inclined hangar door have obvious influence on the flow field,and the research results can provide important reference for relevant studies of littoral combat ships.Firstly,the geometric model of “Independence Class” Littoral combat ship was created,then determine the grid type which was used for the subsequent calculations by comparing the tetrahedral and polyhedral meshes.And based on CFD theory,the steady-state and transient simulation of simplified frigate ship SFS2 was compared with wind tunnel test to verify the effectiveness of the mathematical model and research method used in the numerical calculation of ship flow field,then determine the turbulence model used in the subsequent calculation of this paper,and the independence of the grid is verified.Then get a different calculation conditions by changing the wind speed and wind direction angle,and the airflow field data of littoral combat ship and simplified frigate ship under the same calculation condition were compared and analyzed,this paper shows that under the condition of different wind speed,the law of ship air flow field changing with deck wind speed meet Renault autocollimation principle,It is concluded that the the most suitable wind direction angels for landing are 0° and 30° through analyzing the characteristics of air flow field under different wind direction angles.Finally,the calculation results of three-way velocity,length of reflux zone and streamline distribution of ship flow field of LCS-2 and SFS2 under the same condition are compared and analyzed,the research shows that,the length of downwash airflow area of both ship types decreases with the increase of wind direction angle,hull trailing vortex has more influence on the wake field than island building shedding vortex at 120°;the maximum of upwash speed keeps increasing during the change in wind direction from 60° to 120°,The increment of SFS2 was 114.3%,which was significantly larger than that of LCS-2(55.6%);the most suitable wind direction angle for helicopter landing of two ship types is 0°,but under this condition,The LCS-2 has a maximum washing speed 20% lower than SFS2 within the range of 0.3 to 0.55 times deck length behind the hangar door,considering that the standard take-off and landing point set by LCS-2 is located at the midpoint of the deck length,the air wake field of LCS-2 is more suitable for the take-off and landing of shipborne aircraft than SFS2.