Defense

March 3, 2014

AEDC team supports new measurement capability for turbine blades and vanes

Tags:
Dr. Robert Howard and Martha Simmons
Arnold AFB, Tenn.

This photo of a phosphor-coated dual vane section of a gas turbine engine, is positioned downstream of the AEDC J85 engine at the University of Tennessee Space Institute Propulsion Research Facility. The luminescence produced by the green laser beam and projected onto the phosphor-coated surface (left) is used to measure surface temperature.

The Air Force requires a new measurement capability to monitor the surface temperature of thermally-barrier-coated blades and vanes on the first turbine stage of military fighter engines. Accurate quantification of temperature will allow increased performance of military fighter aircraft.

A method for measuring the surface temperature of blades and vanes in the hot section of turbine engines using a thermographic phosphor technique is being developed by NASA Glenn Research Center, Cleveland, Ohio in collaboration with AEDC and the Propulsion Instrumentation Working Group.

The measurement technique requires coating the blade and vane surfaces with a phosphor material appropriate for the targeted temperature range. The phosphor material is excited by a pulsed laser beam and the temperature determined from the time-rate-of-decay of the luminescence signal.

During a week of testing, NASA demonstrated the TGP measurement technique on a phosphor-coated engine vane section mounted in the exhaust flow field of an AEDC J85 engine at the University of Tennessee Space Institute Propulsion Research Facility. The J85 afterburner exhaust was used to simulate the temperatures experienced by the first stage turbine.

The test program was conducted in two phases; the first phase demonstrated an imaging TGP technique in which the laser and detection camera were mounted off to the side of the exhaust flow. The laser beam was directed to the test article mounted on a water-cooled stand. The camera viewed the surface of the coated vane and recorded two images of luminescence decay at different times after each laser pulse.

Thermographic phosphor techniques were demonstrated in the exhaust flow of an AEDC J85 afterburning engine at the University of Tennessee Space Institute Propulsion Research Facility. This photo shows the test article mounted behind the J85 engine.

The second phase demonstrated an optical-probe that was inserted into the water-cooled mount to within an inch of the vane surface. This approach simulated insertion of the probe into the turbine section of an engine. The laser beam was transmitted through an optical fiber into the probe and focused onto a single spot on the vane surface. Optical fibers mounted around the laser fiber collected and transmitted the thermographic luminescence radiation to a photomultiplier detector located in the control room about 50 feet away from the engine. The fast response silicon detector recorded the temporal luminescence decay for each laser pulse. For both imaging and point measurement techniques, the temperature was deduced from the temporal decay; two images displaced in time for the imaging technique, and the continuous decay signal recorded for the single point probe technique. An eight micron-wavelength pyrometer system was used to independently monitor the temperature of the vane surface during both phases of testing.

Jeff Eldridge, the NASA Glenn Research Center project manager for the test, expressed appreciation for the excellent support provided by the ATA Technology staff and praised the J85 PRF as a great environment for research, particularly for transitioning laboratory technology to engine test maturity.

NASA successfully demonstrated the TGP temperature imaging technique under pseudo realistic engine conditions as well as a fast response, engine-insertable temperature probe that may be suitable for direct measurement of rotating blades’ temperatures.
Eldridge stated, “The combination of a unique test facility with excellent support makes testing at the Propulsion Research Facility a great value. Based on our experience, I hope we have an opportunity to test again in the future.”




All of this week's top headlines to your email every Friday.


 
 

 
Air Force photograph by SrA. Divine Cox

Kunsan AB hosts Exercise Max Thunder 14-2

Air Force photograph by SrA. Divine Cox A South Korean air force F-15 Strike Eagle lands Nov. 17, 2014, during Max Thunder 14-2 at Kunsan Air Base, South Korea. U.S. Air Force, Army, Marine Corps and Navy personnel and aircraft...
 
 

Three bases identified as F-16 aggressor candidate bases

U.S. Air Force photo by Tech. Sgt. Joseph Swafford Jr. A U.S. Air Force F-16 Fighting Falcon fighter aircraft assigned to the 18th Aggressor Squadron lands at Eielson Air Force Base, Alaska, Oct. 6 during RED FLAG-Alaska 15-1. RF-A is a series of Pacific Air Forces commander-directed field training exercises for U.S. and partner nation...
 
 
Air Force photograph

Arc-heated facilities at AEDC offer unique test capabilities for hypersonic programs

Air Force photograph This photo shows the arc heater H3 being test fired prior to the installation of a model injection system. The AEDC High Temperature Materials Characterization and Evaluation is unique in capability and is ...
 

 
Navy photograph

U.S. Navy commemorates C-2 Greyhound’s 50th anniversary of first flight

Navy photograph Nov. 18 marked the 50th anniversary of the first flight of the Navy’s C-2A Greyhound. The “workhorse” of the fleet took to the skies Nov. 18, 1964, from Bethpage, N.Y.   For nearly 50 years, the C-2A ...
 
 

Air Force announces criteria for KC-46A Reserve basing

After extensive internal review, the Air Force on Nov. 9, released the basing criteria that will be used to select candidate bases for the first Reserve-led KC-46A main operating base. The KC-46As will begin arriving at the first Air Force Reserve-led global mobility wing in fiscal year 2019. The basing criteria under consideration include mission...
 
 
Air Force photograph by A1C Erin R. Babis

The footprint of the Jolly Green Giant

Air Force photograph by A1C Erin R. Babis Airmen from the 56th Rescue Squadron tackle Capt. Robert Smith, 56th Rescue Squadron executive officer, after his fini-flight, or final flight, at Royal Air Force Lakenheath, England, N...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>