Performance analysis of rotatable energy system of high-altitude airships in real wind field

Abstract

Energy output and consumption play a decisive role in the endurance of high-altitude airships. Although rotatable energy system (RES) based on the sun tracker is beneficial to the improvement of output performance of high-altitude airships, the effects of wind velocity and airship attitude angles on energy consumption are often ignored. The aims of this paper are to analyze the performance of RES of high-altitude airships and to obtain a favorable operating strategy in real wind field. The energy output models of high-altitude airships using RES and fixed energy system (FES) are presented to study the effect of yaw angle on the output performance. Based on the energy consumption model, the energy consumption of high-altitude airships with the change of wind velocity is calculated. The optimization model and operation strategy to obtain the maximum difference between energy output and consumption are also proposed, and a case study of real wind field is conducted to verify the strategy. The results show that the effects of yaw angle on power output and rotation angle of RES of high-altitude airships are remarkable especially at high latitudes. Moreover, considering the energy consumption from wind resistance, the optimal operating yaw angle of high-altitude airships using FES is to keep upwind angle 0°, and for high-altitude airships using RES, it is feasible to maximize the difference between energy output and consumption by increasing upwind angle of airships, especially when the wind speed is less than 6 m/s.