基于能量平衡的太阳能飞机可持续高度分析

An Effective Theoretical Analysis of Persistent Flight Altitudes of Solar-Powered Airplanes

相对于常规动力型式的长航时飞机,尽量提高太阳能飞机的最大持续任务高度,更能体现其在工程应用中的显著优势。基于能量平衡,采用敏度分析的方法,着重分析了各总体参数对太阳能飞机可持续高度的影响及约束程度。参与分析的总体参数有各系统部件的"效率特性"参数、"重量特性"参数和设计指标中的飞行季节等。研究结果表明:主要有光伏组件效率及其面密度、结构面密度和二次电池比能量共同约束着可持续高度的上限;要实现跨季节或数年飞行时,飞行季节也约束着可持续高度的上限;另外,仅从能量采集与能量消耗之间的差值来看,太阳能飞机"有利"巡航高度约为10 km。所研究的结果能为太阳能飞机方案设计阶段中的总体参数选型提供指导。

Based on the coupling effects among persistent flight altitudes and conceptual parameters of solar pow- ered airplanes under the constraint of energy balance, we investigated the ways how ＂efficiency parameters＂ and ＂weight parameters＂ of every component and the flight seasons of design parameters constrain and influence persis- tent flight altitudes. Sections 1 through 3 explain the theoretical analysis mentioned in the title, which we believe is effective. Sections 1,2 and 3 are entitled respectively： （1） ＂Persistent Altitudes under constraint of Energy Bal- ance＂, （2） ＂Characteristics of Wing Loading and Various Parameters of Every Component＂, （ 3 ） ＂Effect of Each Parameter on Persistent Altitude＂. For convenience, section 2 is divided into four subsections （2. 1, 2. 2, 2.3, and2.4） ; Fig. 1 is the schematic diagram showing the relationship between wing loading on the one hand and vari- ous parameters of every component on the other. The calculated results, presented in Figs. 2 through 8, show pre- liminarily that ： （ 1 ） it is mainly absorption efficiency and area density of photovohaic panels, area density of struc- ture and energy density of battery that constrain the upper limits of persistent flight altitudes ; （2） if a solar powered airplane is required to maintain flight for several seasons or several years, different seasons correspond to different upper limits of persistent flight altitudes ; （3） only from the point of view of remaining energy, which is equal to ab- sorption energy minus consumed energy, the persistent flight altitudes around 10 km enjoy higher advantages. All the research results we believe can guide the effective selection of conceptual parameters to meet design require- ments at the phase of conceptual design of solar powered airplanes.