航空消防大飞机灭火任务顶层指标分解分配方法及应用

Top-level metrics decomposition and allocation method for large firefighting aircraft fireGextinguishing missions and its application

投放有效利用率、投放均匀度等是评估航空消防大飞机灭火任务系统性能的顶层指标。该文建立了航空消防大飞机灭火任务顶层指标半物理半经验模型,明确了顶层指标与灭火任务系统设计阶段参数(包括水箱平均排放流量、投放液体总量等),以及灭火任务规划阶段参数(包括投放液体黏度、投放液体密度、飞行速度、投放高度等)间的量化关系;以既定投放效能要求为目标,逆向应用顶层指标半物理半经验模型,提出了顶层指标分解分配方法。以某典型固定翼航空消防大飞机为例,进行灭火任务顶层指标分解分配,计算得到了应用于灭火任务系统设计阶段的“水箱舱门面积”取值范围,以及应用于灭火任务规划阶段的“灭火剂黏度”和“投放高度-飞行速度”辅助决策平面。结果表明,所提出的分解分配方法可为已有机型的迭代设计和灭火任务规划提供理论依据。

[Objective]The top-level metrics for evaluating the performance of an aircraft fire-extinguishing mission system include effective drop utilization rate and uniformity.The former refers to the ratio of the liquid collected on the ground within the effective coverage area to the dropped liquid;this ensures that sufficient liquid falls to the effective coverage area on the ground.The latter refers to the average thickness of ground coverage within the effective coverage area;this ensures that the thickness of liquid coverage falling to the effective coverage area on the ground meets the requirements of the firefighting task.However,physical modeling and the top-level metrics decomposition and allocation for fire-extinguishing mission systems have not yet been documented.The current work aims to address a semiphysical and semiempirical model for the top-level metrics decomposition and allocation of large firefighting aircraft fire-extinguishing missions.[Methods]Based on the ground pattern and fraction models by Legendre et al.and Gu et al.,respectively,we establish a semiphysical and semiempirical model for the top-level metrics of aircraft fire-extinguishing missions by coupling logical reasoning and theoretical derivation methods.Further,we clarify the quantitative relationship between the top-level metrics and parameters at the design stage(such as the average flow rate and the total amount of liquid dropped)and the planning stage(such as the viscosity of the released liquid,the density of the released liquid,flight velocity,and flight altitude)of the fire-extinguishing mission system.Moreover,the top-level metric decomposition and allocation method is proposed by reversely applying the semiphysical and semiempirical model with a predetermined liquid release performance requirement as the goal.This enables rapid calculation of the range of relevant parameter values at the design and planning stages of the fire-extinguishing mission system,providing a theoretical basis for the iterative upgrade design of existing aircraft models and mission planning.[Results]To validate the effectiveness of the top-level metrics decomposition and allocation method for aircraft fire-extinguishing missions,this study decomposes and allocates the top-level metrics for a typical fixed-wing large firefighting aircraft fire-extinguishing mission system,obtaining the“hatch area”range for the design stage and the“fire-retardant viscosity”and“flight altitude–flight velocity”decision-making planes for the planning stage of the fire-extinguishing mission.[Conclusions]The results indicate that the proposed decomposition and allocation method can,to some extent,guide the optimization design and fire-extinguishing mission planning of the fixed-wing aircraft fire-extinguishing mission system.