60335 - A Study on the Aerodynamic Characteristics of a Blended-Wing-Body Aircraft With a Serpentine Inlet Using Flow Control Techniques 

Demands of a modern aircraft regarding its aerodynamic performance and high efficiency are ever-growing. An S-shaped inlet, referred to as a serpentine inlet, plays a significant role in increasing fuel efficiency. Recently, the serpentine inlet is commonly employed for Boundary layer ingestion (BLI) propulsion which reduces about 3 to 4 % of total aircraft fuel. However, delivering a non-uniformly distorted flow to the engine face (Aerodynamic interface plane, AIP) from a serpentine inlet is inevitable due to the existence of flow separations and swirl flow in the duct. The effect of distortion is to cause the engine compressor to surge; thus, it may impact on the life-cycle of aircraft engine. In this study, aerodynamic characteristics of a serpentine inlet with a blended-wing-body (BWB) aircraft was thoroughly investigated to determine where and how the vortex flow was generated. In particular, a combination of passive and active flow control was implemented at a place where the flow separation was occurred to minimize the flow distortion rate in the duct. The passive and active flow control system were used with vortex generator (VG) vanes and air suctions, respectively. Design parameter of the VG vane is its slit angle from the streamline direction. For the active flow control, the angle of air suctions, arrangement and shape of suction holes have been selected. To evaluate the performance of flow control system, it is necessary to quantify the flow uniformity at the AIP. Therefore, distortion coefficient (DC60) was used as the quantitative measure of distortion. Since the value of DC60 must be less than 20% as a manufacturing requirement, the main objective of this research aimed to keep the DC60 under the requirement with any given condition.