Hydrogen Optimized multi-fuel Propulsion system for clean and silEnt aircraft

国际民航组织在新冠肺炎疫情后的预测估计，低至高收入的旅客公里增长率将增长2.4%-4.1%。空中交通的增长不可避免地增加了航空的燃烧和声排放，从而加剧了航空对当地和全球的环境影响。HOPE将提供一个集成的飞机推进系统，包括两个多燃料超高涵道比（UHBR）涡轮风扇发动机，一个基于燃料电池的辅助推进和动力单元（FC-APPU），驱动一个基于管翼飞机结构的后边界层进气（BLI）推进器。HOPE系统：1)在着陆和起飞（LTO）期间最大限度地减少燃烧和噪音排放，从而影响机场附近的空气质量和噪音烦恼，而不会权衡巡航排放；2)对现有飞机结构进行改造，在短时间内实现大幅减排；3)降低仅在现有管翼飞机结构中使用氢气的风险；4)通过评估和开发几种不同成熟度的绿色推进技术，使航空能源转型更加顺利。HOPE的排放目标包括：与2020年最先进的技术（A320neo）相比，LTO NOx: -50%, CO: -50%，烟尘：-80%，感知噪声：-20%（每次运行约3 dB），气候影响：-30%。为此，HOPE将：1)设计一个集成的飞机推进系统，可容纳多燃料（煤油/可持续航空燃料+氢）UHBR涡扇发动机，FC-APPU和后部BLI推进器；2)探索BLI推进器与FC-APPU相结合的零排放滑行新思路；3)首次对未来超高压沸水涡轮风扇发动机采用H2+煤油/SAF低排放多燃料燃烧技术进行建模、试验和论证；4)评估HOPE技术降低噪音和排放的社会影响、环境负担和成本效益；5)制定政策和建议，引进HOPE技术。

The ICAO Post-COVID forecasts estimate a 2.4%-4.1% increase for a low to high revenue passenger-kilometres growth rate. Air traffic growth inevitably increases aviation's combustion and acoustic emissions, hence aggravating aviation's environmental impact locally and globally. HOPE will deliver an integrated aircraft propulsion system comprising two multi-fuel ultra-high bypass ratio (UHBR) turbofan engines, a fuel cell based auxiliary propulsion and power unit (FC-APPU) driving an aft boundary layer ingestion (BLI) propulsor based on tube-wing aircraft configuration. The HOPE system: 1)minimises the combustion and noise emissions during landing and takeoff (LTO), hence the impact on air quality and noise annoyance near airports, without the trade-off of cruise emissions; 2)retrofitsthe existing aircraft configuration, allowing the substantial emission reduction to be achieved within a short time; 3)de-risks the use of hydrogen solely in existing tube-wing aircraft configurations; 4)smoothens aviation’s energy transition through assessment and exploitation of several greener propulsion technologies at different maturity level. HOPE emission goals consist of LTO NOx: -50%, CO: -50%, soot: -80%, perceived noise: -20% (~3 dB per operation), and climate impact: -30%, compared to state-of-the-art technology in 2020 (A320neo). To this end, HOPE will: 1)Design an integrated aircraft propulsion system accommodating multi-fuel (kerosene/sustainable aviation fuel +hydrogen) UHBR turbofan engines, FC-APPU, and an aft BLI propulsor; 2)Explore the novel idea of combining a BLI propulsor with FC-APPU for zero-emission taxiing; 3)Model, experiment, and demonstrate for the first time a low emission multi-fuel combustion technology burning H2+kerosene/SAF for future UHBR turbofan engine; 4)Assess societal impact, environmental burden, and cost benefits of the reduced noise and emissions by HOPE technology; 5)Formulate policy and recommendations to introduce HOPE technology.