General Information:
AHRTA is a research and technology partnership, based in Pebble Beach, California, founded for the purpose of performing research and analysis in the fields of aeronautical and hydronautical engineering and for the purpose of developing, fabricating and marketing new products in the fields of aeronautical and hydronautical engineering.
Objectives of AHRTA:
- Conduct research studies in the fields of aeronautical and hydronautical engineering using the partners’ knowledge and expertise in the fields of aerodynamics, hydrodynamics aeroelasticity, and hydroelasticity.
- Develop, market, and sell computer programs in the fields of aeronautical and hydronautical engineering.
- Develop, market, and sell air and water vehicles where the partners have developed unique capabilities.
- Develop, market, and sell unique hydro- and wind power generators where the partners have developed unique capabilities.
Who We Are:
AHRTA’s two principal partners are Dr. Max Platzer and Dr. John Ekaterinaris.
Max Platzer has over forty years of aerospace engineering experience. He was a member of the Saturn space launch vehicle development team at the NASA Marshall Space Flight Center, chief of the aeromechanics research group at the Lockheed-Georgia Research Center and professor of aeronautics and astronautics at the Naval Postgraduate School and the Air Force Institute of Technology. He is the author or co-author of seventy journal articles and book chapters on various topics in aerodynamics and aeroelasticity, holder of three U.S. patents, editor/ co-editor of five books and conference proceedings and he served as associate editor of the American Institute of Aeronautics and Astronautics Journal. He is also co-author of a book on unsteady airfoil aerodynamics. He lectured and presented papers at numerous conferences, institutions and universities in the United States and overseas. He is a Fellow of the American Institute of Aeronautics and Astronautics and of the American Society of Mechanical Engineers.
John Ekaterinaris received his PHD from Georgia Tech in 1987. He then joined the Joint Institute of Aeronautics established by the Naval Postgraduate School and the NASA Ames Research Center where he worked with Max Platzer for the following seven years on various steady and unsteady aerodynamic problems. In his follow-on positions as senior research scientist at RISOE National Laboratory in Denmark, Nielsen Engineering & Research in Mountain View, California, director of research at the Institute of Applied and Computational Mathematics in Heraklion, Greece and professor of mechanical & aerospace engineering in Patras, Greece, he expanded his research activities to the development and evaluation of computational fluid dynamics (CFD) for incompressible and compressible flows with applications to unsteady aerodynamics, turbomachinery, hydrodynamics and biofluids, computational investigation of time-dependent flows with application in aeroelasticity, helicopter aerodynamics, and wind turbines, prediction and investigation of unsteady separation, dynamic stall, and flow control mechanisms. He has published thirty seven journal publications and conference papers on these problems.
Products and Services:
The current major business objective is the development and commercial implementation of a new renewable power generation concept first proposed by Max Platzer and Nesrin Sarigul-Klijn at the ASME Energy Sustainability Conference in San Francisco, July 19-23, 2009 (ASME-ES2009-90146). This concept originated from the recognition that only a small part of the renewable power sources available on our planet are presently being exploited because it is generally assumed that only land or off-shore based renewable power sources are exploitable. Yet, seventy percent of the globe’s surface is covered by oceans and vast ocean areas are exposed to strong persistent winds. Therefore we argue that sailing ships equipped with hydrokinetic turbines can convert the ocean wind power into electrical power which, in turn, can be converted into hydrogen and oxygen by means of on-board electrolysers. The hydrogen then is compressed and the pressurized hydrogen tanks are transported back to shore for reconversion into electrical power or for direct use as transportation fuel, heating and cooking.
A second major business objective is the development of a new type of hydropower generator which uses oscillating wings to convert the flow energy of rivers and tidal streams into electrical energy. The basic physical principle underlying this generator is well known in aeronautical engineering. An airfoil which is allowed to oscillate in both plunge (pure translation) and pitch (rotation about some axis on the airfoil chord line) can extract energy from the air or water flow if the phase angle between the pitch and plunge oscillations is close to 90 degrees. We built an experimental model which enforces the plunge and pitch oscillation with the proper phasing between the two motions, as shown in the figure. It has two wings arranged in a tandem configuration so that the two wings also operate with a 90 degree phasing. This model operated quite satisfactorily. AHRTA is now in the process of developing a new model with a simpler mechanism to enforce the phasing between the pitch and plunge motion.
Another objective is the development of unconventional propulsion systems for air and water vehicles. Oscillating wings can again be used for this purpose. They offer certain advantages over conventional propellers in certain applications, such as micro air vehicles (MAVs), like the palm-size MAV shown. Note the two wings arranged as a biplane behind the forewing. The biplane wings can be driven into a flapping motion for thrust generation, while the stationary forewing provides sufficient lift to counteract the vehicle weight. The interesting aerodynamics come about from the interaction between the three wings. The flapping-wing pair actually act to prevent flow separation and stall on the forewing, making the MAV virtually stall-proof, even at flight speeds as low as 2 m/s, and as a propulsion device, the flapping-wing design is about 60 percent more efficient than rotory-wing designs of the same size. We are now developing a vehicle which is also capable of pure hovering flight, similar to the flight capability of a dragonfly or a hummingbird.
AHRTA’s additional business objective is the provision of computational analysis capabilities for various aerodynamic and hydrodynamic phenomena and problems. These capabilities range from potential flow and boundary layer analysis tools to complete Navier-Stokes computations with various turbulence and transition models. We are recognized experts in the analysis of various unsteady flow phenomena, such as dynamic airfoil stall, flows over oscillating airfoils and wings ranging from low speeds to transonic flight speeds, analysis of airfoil flutter and limit cycle phenomena, flows in turbomachines etc. Please refer to our publication list for further information.