基于绿色能源的分布式混合电推进系统性能分析

Performance analysis of distributed hybrid electric propulsion systems based on green energy sources

关键词:  绿色能源  混合电推进  分布式电推进  边界层吸入风扇  能量分配

Key words:  Green energy  Hybrid electric propulsion  Distributed electric propulsion  Boundary layer ingestion fan  Energy split

摘要:

基于绿色能源的电推进飞行器是是航空运输业实现碳中和的重要技术途径。本文旨在利用理论分析和数值计算的手段，研究基于绿色能源的分布式混合电推进系统的性能，重点关注锂电池和固体氧化物燃料电池（SOFC）在航程和载荷方面的影响。本研究构建了一个包含多种能源形式的混合电推进系统架构，并基于能量流建立了功率传递模型，推导出综合考虑部件特征参数、能量分配参数、飞行气动参数的电推进系统航程方程和载荷方程。研究结果显示，在航程方面，锂电池的能量分配系数和能量密度对飞机航程有显著影响，特别是在能量密度阈值之上，增加锂电池的能量分配系数对提升航程有正收益。此外，SOFC的能量分配系数和效率的增加也提高了飞机航程，特别是在其高值区域。在载荷方面，上述锂电池和SOFC参数对飞机零燃料质量（M_ZF）和有效载荷具有重要影响，尤其在高能量密度、高效率和高能量分配系数的情况下飞机的载荷性能改善最佳。参数敏感性分析揭示了升阻比、边界层吸入（BLI）风扇效率、锂电池荷电状态（α_soc）和氢燃料剩余状态（α_soh）对航程的显著影响，其中在以往研究中较少出现的α_soc和α_soh的敏感性分析不容忽视，对其进行更为精确和可靠的状态估计有助于优化航程和载荷的性能表现。

Abstract:

Electric propulsion aircraft utilizing clean energy sources are regarded as a vital means for the aviation industry to achieve carbon neutrality. This study combines theoretical analysis and numerical computations to investigate the performance of distributed hybrid electric propulsion systems based on green energy sources. The primary focus lies in assessing the influence of lithium-ion batteries and solid oxide fuel cells （SOFCs） on aircraft range and payload capacity. This research establishes a comprehensive architecture for a hybrid electric propulsion system， integrating various forms of energy sources. Through energy flow analysis， power transmission models are developed， leading to the derivation of holistic equations that consider component characteristics， energy split factor， and aerodynamic parameters of the electric propulsion system， addressing both aircraft range and payload capacity. The study reveals that lithium-ion batteries have a substantial impact on aircraft range， especially when their energy split factors and energy density exceed certain thresholds. Increasing the energy split factor of lithium-ion batteries beyond these thresholds positively contributes to enhanced aircraft range. Furthermore， an increase in the energy split factor and efficiency of SOFCs also leads to extended aircraft range， particularly in high-value regions. In terms of payload capacity， the parameters of lithium-ion batteries and SOFCs significantly influence both the zero-fuel mass （M_ZF） and effective payload， with the most notable improvements observed in high-energy density， high-efficiency， and high- energy split factor scenarios. Parameter sensitivity analysis underscores the significance of factors such as lift-to-drag ratio， boundary layer ingestion （BLI） fan efficiency， state of charge （α_soc） of lithium-ion batteries， and state of health （α_soh） of hydrogen fuel cells in impacting aircraft range. It's worth noting that α_soc and α_soh sensitivity analyses， which have received comparatively less attention in previous studies， underscore the importance of precise and reliable state estimation for optimizing aircraft range and payload performance.