NASA tests unique embedded jet engine design

The “double bubble” D8 Series is one aircraft design concept that uses boundary layer ingestion. Photo courtesy of NASA/MIT/Aurora Flight Sciences.

The global trend to make cars, trains and aircraft more fuel efficient is becoming more of a reality. NASA is testing a new engine design that will help the aircraft industry reduce its fuel consumption, which will translate to consumer savings and lower emissions.

Engineers at NASA’s Glenn Research Center in Cleveland are testing a new fan and inlet design, commonly called a propulsor.

This new design could help increase fuel efficiency by up to 8 percent more than the engine designs currently being used by airlines.

What makes this new design unique? For the most part, today’s jet engines are located away from the aircraft body. This is done to prevent the engine from ingesting the layer of slow flowing air that develops along the aircraft’s surface, the boundary layer.

Aerospace engineers have modified the traditional design and are hoping that by embedding the aircraft’s engine into these surfaces, they can reduce fuel burn and ingest the boundary layer air flow to propel the aircraft through its mission.

This design change has been somewhat of a challenge for engineers as boundary layer air flow is highly distorted, which affects the way the fan performs and operates. These new designs require a stronger fan.

Extensive testing is required to ensure that the engine design features meets specifications. NASA Glenn is using an 8’ x 6’  Wind Tunnel designed by United Technologies Research Center to test the new propulsor. This rugged boundary layer ingesting (BLI) inlet-fan combination is the first of its kind ever to be tested.

“Studies backed by more detailed analyses have shown that boundary layer ingesting propulsors have the potential to significantly improve aircraft fuel efficiency,” said David Arend, a BLI propulsion expert at NASA Glenn. “If this new design and its enabling technologies can be made to work, the BLI propulsor will produce the required thrust with less propulsive power input.”

Arend also notes that the new design also includes aircraft drag and weight reduction benefits.

Throughout testing, the team will change the wind speed and vary the boundary layer thickness and fan operation to see how these changes affect the propulsor’s performance, operability and structure. Results of the tests will be applicable to multiple cutting-edge aircraft designs being pursued by NASA as well as by its academic and private industry partners.