| Under the requirements of future naval missions,the role of amphibious attack ships that can complete large-scale transportation,armed attacks and other tasks is becoming more and more important.However,there are few studies on amphibious attack ships in China.The study of amphibious attack ships will contribute to China's coastal defense construction.The take-off and landing of amphibious attack ship helicopter has been a prominent problem since its existence.The time-varying sea surface will cause the ship to roll and pitch,which will lead to the unsteady effect of the dynamic surface flow field and the instability of the helicopter's take-off and landing flow field.Compared with the static state,the dynamic flow field of the ship is more in line with the real sea conditions,which has important reference significance for the actual take-off and landing of helicopters,and also provides a reference for the construction of amphibious attack ships in ChinaIn this paper,wind tunnel experiment model,water tunnel experiment model,helicopter rotor model and dynamic mechanism capable of rolling or pitching motion in wind tunnel or water tunnel are designed.Using flow visualization technology and PIV flow field measurement technology,the static surface flow field structure was studied,and the regions with great influence and drastic change in the flow field under different wind directions were found.The variation characteristics of surface flow field and downwash flow at helicopter take-off and landing positions under different pitching motions were studied.The variation of surface flow field under the condition of aircraft-ship coupling was studied.Finally,the preliminary study of flow control is carried out.The results show that under the condition of pitching motion,the variation law of flow field is different from that of static state,even the opposite situation exists. |
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