Applied Research translates the advanced concepts and ideas from Basic Research into solutions to specific problems. NCPA’s Aeroacoustics Research program is concerned with noise and vibration from aircraft and missiles. The motivation is to reduce the impact of environmental noise and the degradation of aircraft or missiles due to vibration and noise. Our Insect Acoustics research seeks to use acoustics to detect insects and/or modify their behavior. The primary efforts have been directed towards termites and fire ants, which cause large economic losses in the Southeastern US. The Applied Acoustics research program includes the design and testing of ultrasonic instruments to count and size catfish in commercial ponds and to assess sediment content in water streams. Altogether, NCPA’s Applied Research effort provides numerous opportunities for technology transfer and the formation of new businesses.

Major Accomplishments

The largest thrust in Applied Acoustics is the aeroacoustics activity. Research is aided by a supersonic nozzle to test designs and a 12 by 12 inch hypersonic wind tunnel with the most advanced optical flow diagnostics available is scheduled for completion in late 2005. Laboratory tests are supplemented by engine test stand tests and full flight tests. A recent change to an F-18 engine has shown to produce a noise reduction of 3 dB while improving fuel efficiency. The innovative approaches to engine noise reduction and improved efficiency has led to the establishment of the FAA/NASA Center of Excellence in Aircraft Source Noise Mitigation.

Insects use acoustics to communicate and produce sound during their normal activities. Early research at NCPA led to the use of synthesized sound to cause female crickets to enter a funnel and water trap eliminating this pest from golf courses without insecticides. A more recent research program devoted to acoustic detection of termites led to the formation of a very successful company in the region to exploit this technology. By using acoustics to carefully localize infestations, the area of treatment can be identified so that the volume of chemicals used can be reduced.

Ultrasonics provides an effective imaging tool in murky or muddy water. The Aquascanner© developed at NCPA to count catfish in commercial ponds is an excellent example of the potential of ultrasonics. The scanner is sonar that receives a return from each fish in the pond and sums over all directions to get a total inventory of the pond. The counting version is ready for market. Similar technology is being used in local creeks and rivers to evaluate the number of sediment particles being carried by the fluid flow. Such knowledge is important in evaluating soil loss and erosion control strategies.

Future Goals  

With the establishment of the FAA/NASA Center of Excellence, opportunities for growth and innovative new research directions are numerous. Present plans include the design of an advanced airframe and engine to guide the design of future commercial aircraft and airports. Radical changes in airframe and engine designs will allow future aircraft to be more environmentally friendly and much less expensive to operate. Concepts for air service transform the current fast bus model to “trains in the sky."

Use of acoustics to modify insect behavior requires a more complete knowledge of insect communications. An instinctive activity learned at NCPA and elsewhere is that any insect that flies at night must have a means to survive or avoid attacks by bats. In many cases, flying insects just fold up their wings and fall when exposed to bat ultrasound. Such insects also cease moving when exposed to synthetic acoustic signals providing a means to stop the insects at a selected location. This and other approaches require detailed knowledge of insect behavior and could provide insect control without chemicals.

NCPA is currently expanding the ultrasonic system for counting catfish to include sizing the fish and the sediment particle system to include three-dimensional imaging of fluid flow. An additional area of applied acoustics to be pursued in the future is the use of berms and barriers to control traffic noise. Current noise control barriers often ignore meteorological conditions, which can result in poor or negative performance. By including winds and turbulence in the noise predictions, these natural environmental factors might well enhance other noise control strategies.