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摘要:
针对飞机在波浪水面迫降过程中机身所受的极限冲击载荷大小及其物理成因问题，采用数值模拟方法展开研究，结合有限体积法和流体体积（VOF）法捕捉自由面，采用六自由度（6DOF）模型和整体运动网格（GMM）处理水面与飞机之间的相对运动，模拟飞机的迫降过程。通过选择飞机相对水面下沉速度最大的波面相位作为迫降触水位置，预报机身所受的极限冲击载荷大小。结果表明：在波浪水面迫降的触水阶段中，机身遭遇了平静水面未预见的冲击峰，同时冲击峰值大小与飞机相对水面的下沉速度有关。此外，对比了在5种不同波高海况下飞机迫降的运动姿态和过载变化历程，给出了波高对极限冲击载荷和其余各参数峰值的影响规律，为飞机载荷分布设计提供参考依据。
Abstract:This paper uses numerical methods to study the magnitude of the maximum impact load on the fuselage and its physical cause during the compulsory landing of the wave. In the numerical calculation, the finite volume method and Volume of Fluid (VOF) method are used to capture the free surface. The Six-Degree-of-Freedom (6DOF) model and the Global Motion Mesh (GMM) are used to process the relative motion between water and the aircraft, and simulate the forced landing process of the aircraft. By selecting the wavefront phase of the aircraft that has the maximum sinking speed relative to the water surface as the position of the forced landing water contact, the ultimate impact load on the fuselage is predicted. The results show that during the water-impacting stage of the wavy surface, the fuselage encounters an unforeseen impact peak on a calm water surface, and the magnitude of the impact peak is related to the sinking speed of the aircraft relative to the water surface. This paper also compares the movement attitude and overload change history of aircraft forced landing under five different wave height sea conditions, and gives the influence rules of wave height on the maximum impact load and the peak values of other parameters, which provides a reference for the design of aircraft load distribution.
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Key words:
- aircraft ditching /
- wave surface /
- impact load /
- computational fluid dynamics /
- Volume of Fluid (VOF)
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图 2 模型F的实验结果和数值模拟结果对比
Figure 2. Comparison between experimental and numerical simulation results for model F
图 4 波浪水面形状与垂向速度分布
Figure 4. Wavy water surface shape and vertical velocity distribution
图 5 π相位触水平静与波浪水面迫降过载综合曲线
Figure 5. Overload history of ditching on calm and wavy watersurface with water contact at π phase
图 6 平静与波浪水面飞机触水部位(π相位)
Figure 6. Water contact position of aircraft on calm and wavy water surface (π phase)
图 7 触水阶段飞机姿态与水面形态(π相位)
Figure 7. Aircraft attitude and water surface morphology during water contact stage (π phase)
图 9 冲击峰值时刻机身触水部位压力系数云图(π相位)
Figure 9. Pressure coefficient contours on water contact area of fuselage at the moment of impact peak (π phase)
图 10 冲击阶段飞机姿态与水面形态(π相位)
Figure 10. Aircraft attitude and water surface morphologyduring impact stage (π phase)
图 11 冲击阶段运动状态与过载变化历程(π相位)
Figure 11. Motion state and overload history during impact stage (π phase)
图 12 俯仰力矩峰值时刻入水部位的压力系数云图(π相位)
Figure 12. Pressure coefficient contours on water contact area at the moment of pitch moment peak (π phase)
图 13 π/2相位触水平静与波浪水面迫降过载综合曲线
Figure 13. Overload history of ditching on calm and wavywater surface with π/2 phase
图 14 平静与波浪水面飞机触水部位π/2相位
Figure 14. Water contact position of aircraft on calm and wavy water surface (π/2 phase)
图 15 触水阶段飞机姿态与水面形态(π/2相位)
Figure 15. Aircraft attitude and water surface morphologyduring water contact stage (π/2 phase)
图 16 触水阶段运动状态和过载变化历程(π/2相位)
Figure 16. Motion state and overload history duringwater contact stage (π/2 phase)
图 17 0.18 s时刻机身触水部位压力系数云图(π/2相位)
Figure 17. Pressure coefficient contours on water contact area of fuselage at 0.18 s (π/2 phase)
图 18 冲击阶段飞机姿态与水面形态(π/2相位)
Figure 18. Aircraft attitude and water surface morphologyduring impact stage (π/2 phase)
图 19 冲击阶段运动状态与过载变化历程(π/2相位)
Figure 19. Movement state and overload history during impact stage (π/2 phase)
图 20 波浪环境入水部位的压力系数云图(π/2相位)
Figure 20. Pressure coefficient contours on wavy water contact area (π/2 phase)
图 21 不同波高的水面形态和速度分布(π相位)
Figure 21. Water surface morphology and velocity distribution with different wave heights (π phase)
图 24 第1个冲击峰值时刻触水部位压力分布(π相位)
Figure 24. Pressure distribution on water contact area at the moment of the 1st impact peak (π phase)
图 25 不同波高的水面形态和速度分布(π/2相位)
Figure 25. Water surface morphology and velocity distributionwith different wave heights (π/2 phase)
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