OPEN FAN VALIDATION FOR CARBON-FREE AIRCRAFTS (PANDORA)

开放式风扇的概念已经存在了几十年。它的高推进效率与消除机舱阻力和重量相结合，一直以来都是人们希望取代高旁路比的导流扇，减少二氧化碳和氮氧化物排放的理想选择。CS1和CS2计划也做出了相关努力，以追求对转开式转子(CROR)的概念。尽管CROR尚未投放市场，但已经取得了进展，将噪音水平降低到了导管风扇的水平。开放式风扇与管道风扇有几个不同之处，到今天，管道风扇是经过数十年研究积累起来的高度复杂的部件。OP概念及其产品之间的鸿沟太大，一个示例者无法覆盖，因为错误地实现这一概念可能会产生误导性的结论。叶轮机械模拟已经完善了几十年，对于缩小概念和产品详细实施之间的差距至关重要。然而，开放的转子加剧了现有的问题(例如，叶片对叶片的变化，即使是小攻角，二氧化碳和噪声排放之间的强烈耦合，等等)。此外，公开的粉丝缺乏公开可用的数据或测试案例，阻止研究人员验证他们的想法。CS2的第一次全球评估报告称，与上一代管道风扇相比，创新的TP 130 PAX项目的预期噪音降低了-9DB，尽管飞行马赫数较低。本项目的目的是获得中短程飞机非导管单扇的相关噪声和性能实验数据。首先，确认可以以稍微降低风扇效率为代价来实现大约5-10分贝的降噪；其次，验证和扩大数值工具的范围。将建立一个包含项目关键结果的实验数据库，以解锁美国联邦在SAF、氢气、混合动力发动机和飞机配置方面的应用。

The open fan concept has been around for decades. Its high propulsive efficiency combined with the elimination of the nacelle drag and weight has been always appealing to replace high by-pass ratio ducted fans and reduce CO2 and NOx emissions. The CS1 and CS2 programs have made relevant efforts to pursue the contra-rotating open rotor (CROR) concept as well. Though CROR has not made it to market, progress has been done reducing noise levels to that of ducted fans. Open fans exhibit several differences with respect to ducted fans which by today are highly sophisticated components accumulating decades of research. The chasm between the OP concept and its product is too big to be covered by a single demonstrator since a wrong materialization of the idea can give rise to misleading conclusions. Turbomachinery simulations have been perfected for decades and are essential to close the gap between the concept and the detailed implementation of the product. However, open rotors exacerbate existing problems (e.g., blade-to-blade variations even for small angles of attack, strong coupling between CO2 and noise emissions, etc.). Moreover, open fans lack publicly available data or test cases preventing researchers from validating their ideas. The first global assessment of CS2 reported an expected noise reduction of -9dB in the innovative TP 130 pax project with respect to the last generation of ducted fans though at a lower flight Mach number. This project aims to obtain relevant noise and performance experimental data of an unducted single fan (USF) for the short/medium-range aircraft with two objectives. Firstly, confirm that about 5-10 dB noise reduction is achievable at the expense of a slight penalty in fan efficiency, and secondly, validate and expand the scope of numerical tools. An experimental database with the key results of the projects will be built to unlock the application of the USF for SAF, Hydrogen, and Hybrid-electric engine and aircraft configurations.