Mechanical Components

Film Cooling Using Pulsed Coolant

Turbine engine designers routinely use film cooling to cool engine components in the hot-gas flowpath. Film cooling is the process of injecting coolant fluid at one or more discrete locations along a surface exposed to a harsh, high-temperature environment. The film cools and thus protects turbine engine components, enabling the engine's operation at higher turbine inlet temperatures and increasing its thermal efficiency. Current turbine engine designs employ a continuous coolant flow, typically diverting 20%- 25% of the compressor's high-pressure air to cool turbine airfoils. By reducing the volume of high-pressure air needed for turbine blade cooling, designers can proportionately increase the flow available for combustion and thus increase thrust. Therefore, coolant flow reduction is an important design goal in the development of advanced turbine engines.

Posted in: Briefs, Mechanical Components
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AFRL Finding Ways to Decrease Unmanned Air Vehicle Costs

In support of the Aeronautical Systems Center's (ASC) Global Hawk Systems Group, AFRL has undertaken a program to study manufacturing tolerances for laminar flow on aircraft wings. On the drawing board, air vehicle designs have perfectly smooth aerodynamic surfaces, yet it is nearly impossible for manufacturers to fabricate those surfaces without some imperfections. Any surface imperfection, no matter how slight, can affect the properties of the boundary layer— the air flowing nearest an air vehicle's body during flight. In turn, this airflow dramatically impacts the amount of drag an air vehicle experiences. When the boundary layer is smooth, or laminar, drag is minimal; as the boundary layer becomes more turbulent, drag increases. Nonetheless, decreasing the amount of surface imperfection is not always a practical solution, because as the manufacturing processes become more stringent, they also become increasingly expensive and time-consuming endeavors. It is therefore vitally important to determine the relationship between the height, shape, and location of surface imperfections and the resulting performance degradation.

Posted in: Briefs, Mechanical Components
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AFRL Supports Desert Hawk Program

AFRL aeronautical engineers collaborated with the Electronic Systems Center's (ESC) Force Protection Program Office, Hanscom Air Force Base (AFB), Massachusetts, to conduct an in-house effort assessing the Desert Hawk small unmanned air vehicle's (SUAV) performance and exploring potential improvements to that performance. Desert Hawk, also known as the Force Protection Airborne Surveillance System (FPASS), performs air base perimeter defense and other intelligence, surveillance, and reconnaissance tasks.

Posted in: Briefs, Mechanical Components
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Microelectromechanical Systems Inertial Measurement Unit Flight Test

AFRL and Boeing engineers conducted successful flight tests of microelectromechanical systems (MEMS) inertial measurement units (IMU) on the Joint Direct Attack Munition (JDAM). They collected flight data and validated the MEMS IMU technology's capability to provide stable navigation performance and accurate weapon guidance, both with and without Global Positioning System (GPS) updates. Researchers will use this flight data to further refine MEMS IMU technology to enhance future capabilities of air-launched munitions.

Posted in: Briefs, Mechanical Components, Microelectricmechanical device, Navigation and guidance systems, Flight tests
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Fruit Flies

He refers to them as "nature's fighter jets" and has devoted his life's work and an entire lab to monitor their every move. Thus is the relationship existing between Dr. Michael Dickinson and the objects of his attention—fruit flies. Career pursuits aside, Dr. Dickinson's connection to the insects is one he predicts will eventually lead to the development of flying robots capable of performing various covert tasks, such as spying and surveillance.

Posted in: Briefs, Mechanical Components, Surveillance, Biological sciences, Robotics
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Active Flow Control Demonstrated on “Airborne Wind Tunnel”

AFRL engineers, collaborating with aerospace manufacturers and other Air Force groups, recently demonstrated the first-ever airborne active flow control system when they manipulated the airflow behind an F-16 external pod. They significantly altered the turbulent wake using small, electrically controlled, piezoelectric synthetic jet (PESJ) actuators. This demonstration is just one part of AFRL's multiphase Aeroelastic Load Control program aimed at reducing the weight, complexity, and signature of air vehicles through the introduction of active control technologies.

Posted in: Briefs, Mechanical Components, Aerodynamics
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Total In-Flight Simulator 50th Anniversary

AFRL's Total In-Flight Simulator (TIFS), a Convair C-131 Samaritan aircraft, entered service on March 22, 1955. The C-131 aircraft had performed various transport operations for approximately a decade up to that point, and the Air Force (AF) Flight Dynamics Laboratory—now AFRL— subsequently chose it for a very special mission: developing next-generation air vehicles.

Posted in: Briefs, Mechanical Components
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A New Method for Determining Aeroballistic Parameters From Flight Data

Dr. Gregg Abate, an AFRL exchange engineer, developed a new method for determining aeroballistic parameters from projectile flight data. Assigned to the Fraunhofer Institute for High-Speed Dynamics (commonly known as the Ernst-Mach Institute), Freiburg, Germany, Dr. Abate was a participant in the AFRL-managed Engineer and Scientist Exchange Program, a Department of Defense effort to promote international cooperation in military research, development, and acquisition through the exchange of defense engineers and scientists.

Posted in: Briefs, Mechanical Components
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