Deployable Engine Air-Brake for Drag Management Applications

The most immediate opportunity for this system is to assist NASA in the development of next generation quiet aircraft, including tube and wing (current generation +1) and integrated airframe propulsion system configurations (current generation +2). On approach, these aircraft are likely to have airframe noise levels that are comparable to or in excess of the engines. A quiet air brake device will allow noise reduction by creating drag without the associated unsteady flow structures of devices such as flaps, slats, and undercarriage. In addition, these devices will enable steep approaches, thereby locating the noise source further from the affected communities. Further development of the technology could lead to advanced thrust reverser applications whereby the deployable exit guide vanes can actuate to a closed position to function as thrust reverser blocker doors. An additional application for swirling exhaust flows is in the area of wake vortex avoidance and induced drag management. For example, swirling outflow devices placed on wing tips could be used to counter- or co-swirl relative to the bound vortex that is shed by a finite wing, resulting in potential induced drag reduction or increase (possibly of value in a quiet drag sense). This may prove to have applications in designing more fuel efficient and quiet aircraft in the future.

The commercial potential for this system extends beyond NASA's development programs related to next-generation quiet aircraft. Two complementary potential commercial markets exist for the technology: (1) implementation as a complementary technology in retrofit (ejector) hush kits on older aircraft engines in order to meet current and future noise requirements, and (2) implementation in future jet engines as an integral part of the engine design; i.e., modifying traditional engine exit guide vanes or bypass nozzles with a variable mechanism that generates a swirling outflow in drag management mode. The first market has immediate potential (within the next five to seven years), while the second market, although potentially much larger from a quantity standpoint, is a longer-term endeavor (likely seven to ten years before practical implementation in a new engine that would be part of the first N+2 prototypes). The retrofit market provides a simpler and faster implementation and is an opportunity to demonstrate the effectiveness of the technology to the community before upselling the technology or its derivatives to the engine Original Equipment Manufacturers (OEMs). Another potential application is integration of the technology into tactical UAV and cruise missile platforms that demand high levels of power generation while simultaneously requiring maneuverability and thrust control. More »