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Digital Virtual Aerodynamics Range Highlights Advances in Aerodynamics Research
Virtual fly-out of a spinning projectile through DVAR.
Supercomputers at APG are producing big savings in the development and testing of next-generation precision munitions. An even bigger payoff will come from the recent advances made in time-accurate modeling of unsteady aerodynamics. This will have significant effect in the design of future precision munitions required for battlefield operations in the coming years. Digital Virtual Aerodynamics Range (DVAR) is an example of such advances.
DVAR is a conglomeration of technologies that, for the first time, have resulted in modeling and simulation of "virtual fly-outs" of munitions similar to actual free-flight tests in aerodynamic experimental facilities. A developing technology, DVAR was initiated as a Department of Defense Grand Challenge Project in 2006. Researchers expect its findings to benefit Soldiers on the battlefield within the next decade.
According to Dr. Jubaraj Sahu, an aerospace engineer who serves as team leader of the Advanced Computational Aerodynamics team in WMRD, the goal of the computationally-based research is the ability to perform time-accurate, multidisciplinary, coupled computational fluid dynamic (CFD) and rigid body dynamic (RBD) computations for the flight trajectory of a complex guided projectile, and fly it through the virtual environment the same as it would through a traditional flight test environment.
CFD simulates the flow of fluids, such as air or water around solid objects like planes, missiles and ships. Through work in this area, ARL experts can simulate the flow of air around flying objects such as projectiles, missiles and parachutes and can compute the forces exerted by the air pressure on those bodies. As a result, experts can determine the flight path of projectiles and guide the design of control systems to divert the path of projectiles during its flight when needed.
Unsteady flow computations show the wake region flow resulting from microjet interaction.
The project has the potential of cutting down on the number of tests that are traditionally needed early in the development stages. "The project looks at the development of munitions, particularly precision-guided munitions," said Sahu, who is also deputy chief of the Flight Sciences Branch. "We're seeking the best design in terms of aerodynamic characteristics and how quickly we can optimize designs for best flight performance."
The traditional way of doing these types of tests, Sahu said, was based on experimental testing. "We built a model and that took a lot of time," he noted. "We were unable to see the details of the flow field and detailed insight as to what happens during a flight maneuver, for example. It used to take us weeks, even months from research to actual testing."
"With DVAR, we have unlimited visualization," he added. "Downside, it now takes three days, running 24 hours each day to perform a DVAR test on a 100-meter virtual range. Eventually, we will be able to test that in two hours on a computer workstation. But with DVAR, the test range is not limited to caliber (size) or speed."
This kind of research was impossible 10 years ago, primarily because of the limitations on computer technology. But with access to the high-performance computers at the DSRC, Sahu is able to compute the unsteady aerodynamic forces and moments and the flight trajectories of projectiles in an integrated way.
DVAR has been successfully demonstrated on a number of spinning and finned projectiles, most notably the 40-mm grenade for the M203 launcher, which is a separate Grand Challenge Project, the Self-Correcting Projectile for Infantry Operation (SCORPION).
The SCORPION program used successfully-applied advanced state-of-the-art, time-accurate CFD techniques developed and applied in the DVAR program and Micro Adaptive Flow Control (MAFC). The research showed that MAFC with tiny synthetic jets provides an affordable route to lethal precision-guided infantry weapons.
"We're currently ahead of the rest of the world in projectile aerodynamics research technology and the supporting computerassets of the Department of Defense Supercomputing Resource Center provides that edge," said Sahu. "These capabilities allow our team to perform aerodynamics research faster than others. Also, our totally physics-based, high fidelity computing modeling capabilities have isolated that core advantage."