现代航空的飞速发展对飞行器的安全性、可靠性、环保性和经济性提出了更高的要求。对于传统的涡扇发动机，这就要求更高的涡轮前温度、更大的压气机增压比，更大的涵道比等，由于材料、风扇尺寸等的限制，传统推进系统提升空间有限。分布式推力作为一种可行的解决方案，成为了当下一个重要的研究方向。推力矩阵是实验室提出的一种新型分布式推力方案，通过将传统大发动机替换为许多微型发动机，每个微型发动机只需要在设计点工作。通过数目众多的微型发动机不同的开闭状态来实现飞行器力和力矩的输出。在该方案下，飞行器可以有效降低噪声、耗油率和飞行阻力，从而大幅度提升飞行器的载重能力和续航能力。微型发动机尺寸较小，内嵌入翼身融合飞行器当中，发动机进排气会影响飞行器周围的流场分布，引起翼型环量的变化，进而影响机翼的升阻特性。为了方便研究，本文将推力矩阵方案简化为带有边界层抽吸和尾缘射流的二维翼型，采用实验室程序，通过数值分析的方法，分别以对称翼型NACA0012和非对称翼型NACA4412为例来研究不同来流攻角和不同抽吸位置下机翼的升阻特性，为推力矩阵中微型发动机的布置和优化提供初步建议。对于对称翼型和非对称翼型，本文分别计算了來流攻角在-4°到8°之间变化时，0.1C到0.8C八个位置抽吸的具体情况。同时为了更接近实际情况，文中还进行了多段抽吸的计算，针对两种翼型进行了不同的抽吸段组合，并进行比较分析。计算结果表明，单位置抽吸时，在0.5C和0.6C附近抽吸，翼型能够获得更好的升阻特性，发动机进气管路应优先布置在相应位置。同时边界层抽吸对升阻比的提升在不同攻角下效果差别较大，可以通过设置翼型的安装角或者控制飞行器的飞行姿态使得翼型來流攻角主要在高效范围内工作。此外，对称翼型和非对称翼型多段抽吸的不同组合在不同攻角下效果也有所不同，对升阻特性和压力分布影响着较大的差异，需要根据实际情况进行选择。
Modern aviation will require revolutionary solutions to meet public demand for improving safety, reliability, environmental compatibility, and affordability. NASA’s vision for 21st century aircraft is to develop propulsion systems which are intelligent, highly efficient, virtually inaudible, and have near zero harmful emissions. Given the limitations of conventional propulsion systems, distributed propulsion systems have drawn worldwide attention and become one of the most written topics. Propulsion matrix system is a new distributed propulsion system which is come up with by Professor Zhou. By replacing the conventional aero engines with numerous micro engines, every micro just need to operate at the design point. Specific force and moment can be produced by allocating the on and off state of the micro engines. In this system, noise, and fuel consumption rate can be effectively reduced, thus improving the loading compacity and cruising ability.Considering the size of the micro engines, they are embedded inside airfoils, so the intake and exhaust of the engines will affect the flow field distribution, changing the airfoil circulation and aerodynamic characteristics. In my research, the propulsion matrix system is simplified into a two-dimensional airfoil with surface injection and trailing edge jet. A CFD program developed by my lab is used to study the influence of intake and exhaust at different incoming attacking angles and ingestion positions.Symmetric airfoil NACA 0012 and asymmetric airfoil NACA 4412 are chosen in my research based on their rich experimental results. According to the results, when talking about single ingestion position, better performance can be achieved with ingestion around 0.5C and 0.6C. The degree of the improvement varies along with the attacking angle, so an initial incidence angle can be set to make the airfoil work at a more effective range. Multi-ingestion combinations are also studied at different attacking angle. Final selection will based on the real necessity and operation range of the aircraft.
