固定翼民机的新能源关键技术研发现状与展望

Research and Development Status and Prospect of the Alternative Energy Key Technologies for the Fixed-wing Civil Aircraft

新型能源的存储、运输及转化是制约新能源固定翼民机发展的主要“瓶颈”和关键技术,如动力电池的质量能量密度过低导致储能重量过大是制约全电新能源民机发展的“瓶颈”,氢气的体积能量密度过低导致的储能容积过大以及运输困难问题是制约氢能新能源飞机发展的“瓶颈”;可持续航空燃料(SAF)民机的应用则主要受到SAF的转化成本制约。能源到推进的转化(如纯电能推进、氢燃料电池电机推进及油电混动推进)存在的主要问题是高功率密度与大功率电机的研制,使用分布式电推进技术可以部分地解决这类电机问题,但氢燃料电池的质量与体积功率密度仍然是阻碍其在大型飞机上推广应用的主要制约因素,使用氢气作为航空发动机的燃料则不仅存在高压或低温燃料运输及在飞机上存储的技术问题,氢燃料的特殊理化性质也会带来有别于液体碳氢燃料的特殊安全性问题。本文对比和归纳了几种替代能源在民用航空器上应用的可能性,推论得到绿色SAF或液化天然气(LNG)类碳氢燃料,相对直接使用液氢燃料更具可行性,即绿氢与直接大气捕获二氧化碳的化工或生物合成燃料更具可行性,可作为新能源航空器发展的参考和指导。

The storage,transportation and transformation of the alternative energy are the bottlenecks and key technologies that restrict the development of the alternative energy fixed-wing civil aircraft.For example,the low mass energy density of the power batteries leads to the excessive weight of energy storage,which is the bottleneck of the development of the all-electric civil aircraft,and the low volume energy density of the hydrogen leads to the excessive volume of the energy storage and transportation difficulties,which are the bottlenecks of the development of the hydrogen civil aircraft.The application of the SAF fuel in civil aircraft is mainly restricted by the production cost of the SAF fuel.The main problem for the transformation from energy to propulsion,such as the all-electric propulsion,the hydrogen fuel cell propulsion and fuel-electric hybrid propulsion,is the development of high power density and high power motors,which can be partially solved by using distributed electric propulsion technology,but the mass and volume power density of the hydrogen fuel cells are still the main restrictions for its promotion and application in large aircraft.Using hydrogen as fuel for air-breath engines not only has technical problems of high-pressure or lowtemperature fuel transportation and storage on aircraft,but also the special physical and chemical properties of the hydrogen fuel will bring special safety problems being different from the liquid hydrocarbon fuels.The comparison and induction for the application of the alternative energies in civil aircraft are presented,and the conclusion is that the SAF or green LNG fuels may be the most attractive choice for the civil aircraft compared with the direct using of the liquid hydrogen as aeronautical fuel.Or the green hydrogen must be used to synthesize SAF or LNG with the carbon dioxide from the atmosphere.And these can be the references or guidance for the alternative fueled civil aircraft.