Geder J.D.,U.S. Navy |
Geder J.D.,Laboratory for Computational Physics and Fluid Dynamics |
Ramamurti R.,U.S. Navy |
Ramamurti R.,Laboratory for Computational Physics and Fluid Dynamics |
And 3 more authors.
AIAA Guidance, Navigation, and Control Conference | Year: 2010
A full six-degree-of-freedom vehicle model is constructed for a flapping-wing nano air vehicle (NAV) which includes components for the body, wings, sensors, and unique shape memory alloy (SMA) driven actuator mechanisms. The design of these actuator mechanisms and the link between the SMAs and wing kinematics is described. Algorithms for sensory feedback control of the vehicle dynamics are designed and implemented in simulation. The outputs of four control modules command changes in the wing stroke amplitude, mean position, and plane angle. An extended Kalman filter is developed to improve attitude estimation and stabilize the NAV. Vehicle responses to hover, forward flight and turning commands are assessed and desirable performance is achieved.
Ramamurti R.,U.S. Navy |
Ramamurti R.,Laboratory for Computational Physics and Fluid Dynamics |
Geder J.,U.S. Navy |
Geder J.,Laboratory for Computational Physics and Fluid Dynamics |
And 5 more authors.
AIAA Journal | Year: 2010
Three-dimensional unsteady computations of the flow past a flapping and deforming fin are performed. The computed unsteady lift and thrust force-time histories are validated with experimental data and are in good agreement. Several fin parametric studies are performed for a notional unmanned underwater vehicle. The parametric studies investigated the force production of the fin as a function of varying the flexibility, the bulk amplitude of fin rotation, the vehicle speed, and the fin stroke bias angle. The results of these simulations are used to evaluate the hydrodynamic performance of the vehicle and to support controller development. Computations are also performed to map out the hydrodynamic characteristics of a new test vehicle, designed and built at Naval Research Laboratory to demonstrate the hovering and low-speed maneuvering performance of a set of actively controlled curvature fins.
The U.S. Naval Research Laboratory (NRL), in collaboration with numerous universities and government laboratories studying the effects of dusty plasmas — charged dust particles that can occur naturally in the mesosphere — generated an artificial plasma cloud in the upper-atmosphere to validate the theory of 'dressed particle scattering' caused by this phenomenon. Named the Charged Aerosol Release Experiment (CARE II), an instrumented rocket was launched Sept. 16, at 19:06 GMT, from Andoya, Norway, utilizing a NASA Black Brant XI sounding rocket. After entering the ionosphere, 37 small rockets were fired simultaneously to inject 68 kilograms (kg) of dust comprised of aluminum oxide particulates, accompanied by 133 kg of molecules such as carbon dioxide, water vapor, and hydrogen. The launch occurred just after sunset placing the dust particles in sunlight for easy viewing by cameras in darkness on the ground and with an airborne platform. The large concentration of dust and exhaust material interacted with the ionosphere to produce a so-called 'dirty plasma' with high-speed pickup ions. Visibly seen from the ground, the released dust produces an optical cloud, and, by attaching the electrons in the ionosphere, forms charged particulates. This plasma then generates waves that scatter radar signals used for remote sensing. "The CARE launch was fully successful," says Dr. Paul A. Bernhardt, CARE principal investigator. "Ground-based radars tracked the effects on the ionosphere for twenty minutes, providing valuable data on how rocket motors affect ionospheric densities. The data will be used to validate simulations of natural disturbances in the upper atmosphere." The NRL Plasma Physics Division's (PPD) Charged Particle Physics Branch and the University of Washington made measurements with plasma probes and electric field booms on a deployable instrument payload. Ionospheric disturbances were monitored with multi-frequency beacon transmissions from the rocket payload that were detected by a network of ground receivers from the Finnish Meteorological Institute (FMI), Sodankylä Geophysical Observatory (SGO), and NRL PPD. Ground radars and optical instruments that recorded the dust release were provided by the European Incoherent Scatter Scientific Association (EISCAT); Institute of Atmospheric Physics (Germany); Institute of Space Physics, (Sweden); and others. The CARE theory effort was based in PPD and the Laboratory for Computational Physics and Fluid Dynamics (LCPFD) at NRL, as well as the Center for Space Science and Engineering Research at Virginia Tech. High frequency receivers were fielded by QinetiQ (UK) and by NRL PPD with stations in Oslo, Tromsö, and the University Center in Svalbard (UNIS). A CARE data review is scheduled for December 2015 in San Francisco. During this review, Bernhardt says, the scientific results from the experiment will be compared with artificial and natural scatter processes to better understand the physics. Also, a follow-on CARE III experiment will be planned. The Department of Defense (DoD) Space Test Program sponsored the launch and payload integration for the NRL CARE II mission. The rocket launch, and payload development was provided by the NASA Sounding Rocket Program. The CARE experiments were designed to test the theory of dusty plasma scatter developed by scientists at the University of Tromsö in Norway and NRL PPD. About the U.S. Naval Research Laboratory The U.S. Naval Research Laboratory provides the advanced scientific capabilities required to bolster our country's position of global naval leadership. The Laboratory, with a total complement of approximately 2,500 personnel, is located in southwest Washington, D.C., with other major sites at the Stennis Space Center, Miss., and Monterey, Calif. NRL has served the Navy and the nation for over 90 years and continues to advance research further than you can imagine. For more information, visit the NRL website or join the conversation on Twitter, Facebook, and YouTube.
Kaplan C.R.,U.S. Navy |
Kaplan C.R.,Laboratory for Computational Physics and Fluid Dynamics |
Bernhardt P.A.,U.S. Navy
Journal of Spacecraft and Rockets | Year: 2010
The direct simulation Monte-Carlo (DSMC) method was used to simulate the shuttle burn and to study the interaction between the shuttle exhaust and the neutral species of the background atmosphere. The simulations were carried out with a two-dimensional, time-dependent DSMC code, that uses variable hard sphere (VHS) particles with the modified no-time-counter scheme to select collision pairs, and includes translational-rotational energy exchange based on the Larsen-Borgnakke model. The calculations show that when the altitude-dependence of the background atmosphere is included in the simulation initial conditions, the shape of the shuttle exhaust plume is skewed. This is because the greater atmospheric density and pressure at the lower altitudes creates more drag on the lower part of the plume.
Dr. Jay Boris, Chief Scientist for Computational Physics, working in the Laboratories for Computational Physics and Fluid Dynamics at the U.S. Naval Research Laboratory (NRL), has received the Numa Manson Medal for distinguished contributions to the dynamics of explosions and reactive systems. Established in 1975 by the Institute for the Dynamics of Explosions and Reactive Systems, the award recognizes mature scientists whom are distinguished by lifelong accomplishments elucidating the prominent features of the dynamics of explosions and reactive systems. Dr. Boris was recognized for Flux-Corrected Transport (FCT) and Monotone Integrated Large Eddy Simulation (MILES), theoretical and numerical techniques that he developed at NRL. These reactive flow techniques have been instrumental in uncovering key aspects of the dynamics of explosions and reactive systems over the past three decades by scientists at NRL and around the World and have also allowed NRL to develop the instant-response CT-Analyst model for urban defense against airborne weapons mass destruction. Dr. Boris plans and leads research on advanced analytical and numerical capabilities and their engineering applications to solve problems vital to the Department of Navy (DoN), the Department of Defense (DoD), and the nation. His responsibilities include the development of advanced computing architectures for parallel processing and the applied mathematics relevant to creating unique new solution methods. A Charter Member of the Senior Executive Service (SES) since 1979, Dr. Boris has been a member of the civil service for 44 years. He was Director of the Laboratory for Computational Physics and Fluid Dynamics, from 1978 to 2011 when he converted to a Scientific and Technical (ST) position and then attached as NRL Chief Scientist, to the Laboratories for Computational Physics and Fluid Dynamics (LCP&FD). Boris joined the NRL in 1971 as a senior consultant in the Plasma Physics Division. From 1975 to 1978 he was head of NRL's Plasma Dynamics Branch. He received the bachelor's degree in physics (1964) and master's and Ph.D. degrees in astrophysical sciences (1968) from Princeton University. He then joined Princeton's Plasma Physics Laboratory before coming to NRL. About the U.S. Naval Research Laboratory The U.S. Naval Research Laboratory provides the advanced scientific capabilities required to bolster our country's position of global naval leadership. The Laboratory, with a total complement of approximately 2,500 personnel, is located in southwest Washington, D.C., with other major sites at the Stennis Space Center, Miss., and Monterey, Calif. NRL has served the Navy and the nation for over 90 years and continues to advance research further than you can imagine. For more information, visit the NRL website or join the conversation on Twitter, Facebook, and YouTube.