Experimental research on aero-propulsion coupling characteristics of a distributed electric propulsion aircraft

Distributed Electric Propulsion (DEP) aircraft use multiple electric motors to drive the propulsors, which gives potential benefits to aerodynamic-propulsion interaction. To investigate and quantify the aerodynamic-propulsion interaction effect of the wing section, we built a DEP demonstrator with 24 “high-lift” Electric Ducted Fans (EDFs) distributed along the wing’s trailing edge. This paper explores and compares the aero-propulsion coupling characteristics under various upstream speed, throttle, and EDF mounting surface deflection angles using a series of wind tunnel tests. We compare various lift-augmentation power conditions to the clean configuration without propulsion unit under the experiment condition of 15–25 m/s freestream flow and angles of attack from ?4° to 16°. The comparison of computational results to the experimental results verifies the effectiveness of the computational fluid dynamic analysis method and the modeling method for the DEP configuration. The results show that the EDFs can produce significant lift increment and drag reduction simultaneously, which is accordant with the potential benefit of Boundary Layer Ingestion (BLI) at low airspeed.     

短切碳纤维增强环氧树脂形状记忆复合材料的制备与性能研究

为实现形状驱动能耗与复合材料力学性能的最佳配合，本文在热致环氧形状记忆聚合物基体中提高增韧剂新戊二醇二缩水醚（NGDE）含量来降低其玻璃化转变温度，同时添加短切碳纤维（SCF）来抵消由增韧剂引起的刚度降低负面效果。通过实验研究了不同NGDE、SCF含量对复合材料形状记忆转变温度、形状记忆性能和力学性能的影响。结果表明，增加NGDE含量可将环氧聚合物基体的形状记忆转变温度从90 ℃降至43 ℃，其储能模量和弯曲模量也随之降低。在11wt%NGDE上添加SCF后，复合材料的玻璃态储能模量、橡胶态储能模量、弯曲模量最高可提高至原始试样的1.9倍、7倍和2.4倍。     

短碳纤维增强聚醚醚酮注塑成型进气道的性能北大核心CSCD

以含20%的短碳纤维增强聚醚醚酮树脂为主要原料,采用注塑成型的方法制备了进气道及试片。通过对材料力学性能、微观形貌、进气道CT无损检测、内型面三坐标进行分析,结果表明:按照给定的工艺参数注塑成型,复合材料的抗拉强度达208 MPa、拉伸模量16.7 GPa、冲压式剪切强度100 MPa,碳纤维在树脂基体中分布均匀,进气道本体材料内部缺陷较少,进气道内外型面光滑、尺寸精度较高。