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短舱阻力和重量相结合，一直吸引着取代高旁通比涵道风扇并减少CO2和NOx排放。CS 1和CS2计划也做出了相关的努力来追求对转开式转子（CROR）概念。虽然CROR还没有进入市场，但已经取得了进展，将噪音水平降低到管道风扇的水平。开放式风扇与管道式风扇有几个不同之处，管道式风扇是经过几十年研究积累的高度复杂的部件。OP概念与其产品之间的鸿沟太大，无法由一个单一的演示者来覆盖，因为错误的概念实体化可能会导致误导性的结论。涡轮机模拟已经完善了几十年，对于缩小产品概念和具体实施之间的差距至关重要。然而，开放式转子加剧了现有的问题（例如，即使对于小迎角，叶片与叶片之间的变化，CO2与噪声排放之间的强耦合等）。此外，开放的粉丝缺乏公开的数据或测试案例，这阻止了研究人员验证他们的想法。CS2的第一次全球评估报告说，尽管飞行马赫数较低，但与上一代涵道风扇相比，创新的TP 130 pax项目的预期噪音降低了-9dB。本计画旨在取得中短程飞机无涵道单风扇之相关噪声与性能实验资料，有两个目的。首先，确认在风扇效率略有下降的情况下可以实现约5-10 dB的降噪，其次，验证并扩展数值工具的范围。将建立一个包含项目关键结果的实验数据库，以解锁USF在SAF、氢和混合动力发动机和飞机配置中的应用。

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.