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.


 
 

 

President proclaims Memorial Day as ‘Day of Prayer’

President Barack Obama May 22 saluted the service and sacrifices of America’s military members–past and present–and proclaimed Memorial Day, May 25, 2015, “as a day of prayer for permanent peace, and I designate the hour beginning in each locality at 11 a.m. of that day as a time during which people may unite in prayer....
 
 

Air Force leaders’ Memorial Day message

Secretary of the Air Force Deborah Lee James and Air Force Chief of Staff Gen. Mark A. Welsh III send the following Memorial Day message to the Airmen of the Air Force and their families: To the Airmen of the United States Air Force and their Families: On Memorial Day, Americans pause in solemn remembrance...
 
 

Headlines May 22, 2015

News: Second Marine killed in Hawaii Osprey crash identified - Marine Corps officials have identified the second Marine to die as a result of the May 17 MV-22B Osprey crash as Lance Cpl. Matthew J. Determan of Maricopa, Ariz.   Business: Israel defense exports plunge to seven-year low - Israeli defense sales last year plunged to their...
 

 

News Briefs May 22, 2015

Ukrainian officer hit with third charge in Russia A third charge has been filed against a Ukrainian military officer who has been behind bars in Moscow for nearly a year over the deaths of two Russian journalists in Ukraine. Nadezhda Savchenko, who worked as a spotter for Ukrainian troops fighting separatist rebels in eastern Ukraine,...
 
 
Army photograph by C. Todd Lopez

Smart-mortar will help Soldiers more effectively hit targets

Army photograph by C. Todd Lopez Nick Baldwin and Evan Young, researchers with the Armament Research Development and Engineering Center at Picatinny Arsenal, Pennsylvania, discuss the 120mm Guided Enhanced Fragmentation Mortar ...
 
 

Air Force assigns new chief scientist

The Air Force announced the service’s new chief scientist to serve as a science and technology adviser to the secretary of the Air Force and the chief of staff of the Air Force, May 21. Dr. Greg Zacharias will be the 35th chief scientist and is ready to “dive in” to his new role. “I...
 




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>