AEDC is location of choice for Small Business Innovation Research test

  • Published
  • By Philip Lorenz III
  • AEDC/PA
ARNOLD AIR FORCE BASE, Tenn. --  When a small business has the opportunity to demonstrate and evaluate one of the latest technological innovations at the world's largest and most advanced ground test complex, the results can be very impressive, said Tyler Neale, a Small Business Innovation Research (SBIR) test manager at AEDC.

This was the situation recently when Dr. Todd Lowe, the vice president for research and development with Applied University Research (AUR) Inc., was on hand for a test of a sub-miniature laser Doppler velocimetry (SM LDV) system sponsored by the Air Force in a small wind tunnel at Arnold.

So, what is an SM LDV and what is it used for?

"It's a measurement system that can get velocity profiles of near-field regions, so we're talking extremely close to the surface of an object, within the boundary layer flow," Neale said. "It's often extremely difficult to get experimental data close to the wall (surface) just because it's either not accessible or you're going to disrupt the flow with whatever measurement techniques you're trying to use there."

By 'object,' Neale is talking about an aircraft, spacecraft or bomb model that is being subjected to flight conditions, which could be smooth or turbulent air flow or a combination in a wind tunnel.

"This system has a probe that will be integrated into the model that's in the wind tunnel," he said. "So, it's inside the model, and it will use an array of lasers to gather flow velocity information, getting flow field data that was previously unattainable. Often times there are some highly complex flow features within boundary layers, particularly when turbulent, that are difficult to characterize using traditional techniques. These complex features can dramatically affect the aerodynamics of a body. With the SM3 LDV system, we are hoping to gain a better understanding of the flow in these regions of high complexity to improve designs and potentially use the data to compare with and validate computational solutions."

According to Dr. Lowe, this region close to aerodynamic bodies such as aircraft, missiles and rockets is critically important to the performance of the entire vehicle.

"The capability to make three-dimensional velocity measurements in the near-field region of models in AEDC's unparalleled facilities will help engineers improve a variety of cutting-edge aerospace technologies," he said. "Data may be used for understanding issues with configurations under test in addition to providing detailed information to validate flow calculations, which are being used increasingly to make important design decisions."

Neale said the data, which would have contributed to previous programs, is still needed for ongoing and future work.

"In the past there have been tests where it would have been very useful to have some sort of measuring technique for near the surface of a model," he said. "I know with the space shuttle return to service studies, there's been a need for that. The JDAM (Joint Direct Attack Munition) had a flow anomaly on its surface that would have benefitted from this sort of technique - there would be applications for tests where we need to characterize the flow along the surface of a model.

"There has been a demand for it, not just here at AEDC, [but] this would be applicable to other wind tunnels and [test] jet engines. You could put this system inside a jet engine and see the flow that's going into the engine, into the compressor. It will give you high resolution, three-component boundary layer velocity profiles which we previously wouldn't be able to do. It will just complement some of the other measuring techniques that we have in there like BOS (Background Oriented Schlieren) and PIV (Particle Image Velocimetry) and whatever other technology we utilize for the tunnels."

Neale said the SM LDV system is a smart investment.

"I guess another thing I would say with AUR, Inc., the SBIR program is really important and it's a really good thing; it's both beneficial for the government and for small businesses in the nation," he said. "AUR is an example of the success that the government can realize through this program - they've (AUR) listened to our advice and our inputs on questions they've asked in developing the system. And I'm confident that they're going to give us a pretty robust and useful system that will help compliment our already pretty wide array of flow visualization technologies. They're one of the success stories from the SBIR program that justifies spending the money on this."

Dr. Lowe said ground test applications for the SM LDV, which is suited for "16T in particular" would include "new missiles, airframes and store separations" and be useful for testing "particularly [in the] Mach 2 to Mach 4 regimes."