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iSGTW Feature - NYSGrid and the Lord of the Wings

Feature - NYSGrid and the Lord of the Wings

This illustrates the pressure contour plot of the air flow field around a rotator wing that is at the highest angle of attack over 50% and 99% position of span. (Top is 3-D representation, bottom is 2D.)

Image courtesy of Ercan Dumlupinar.

British actor Sean Bean won't fly. On at least one occasion during filming of The Lord of the Rings, he forced the air-lifted cast to wait on a snowy mountaintop while he ascended on foot to join them. He just didn't trust the helicopter. Bean (and his future colleagues) might be happy to know that somebody's working to make helicopters safer.

A research team, led by Vadrevu Murthy from the department of Mechanical and Aerospace Engineering at Syracuse University, studies aerodynamic loads on helicopter rotors that transfer directly to the vehicle's control system. The team's numerical simulations of air flow are expected to advance helicopter rotor technology and lead to designs that avoid instability (and nervous would-be passengers).

Helicopter rotor flow is unsteady even for steady flight. The pitch of the blade must vary to offset the different lifts felt by the advancing and retreating blades. On the retreating side, the angle of attack is larger, and the flow sometimes stalls. Stalling on a helicopter rotor at high speed or in maneuvering flight causes pitching forces on the blade and loads on the control system that in turn cause fatigue problems for critical helicopter rotor components.

To model the air flow, team member Ercan Dumlupinar uses the commercial version of the Cobalt application developed by Cobalt Solution, LLC to solve a set of equations that describe fluid flow and similar phenomena. The MPI (Message Passing Interface) Cobalt jobs communicate with each other during execution and require significant computing resources.

Top picture shows a schematic representation of fundamental research areas. Bottom picture illustrates air velocity on advancing and retreating sides.

Image courtesy of Ercan Dumlupinar.

Dumlupinar needed more CPUs than were available at SU. Steve Gallo of the Center for Computational Research (CCR) in Buffalo, a NYSGrid site, and Jorge Gonzalez-Outeirino, of ITS-Syracuse University, helped him move the processing to the CCR. They used Globus tools to push the files required by Cobalt to this site, and Dumlupinar ran the simulations there through NYSGrid. He's run six sets of simulations, each taking 78 CPU hours on 16 nodes.

The researchers have validated the computed flow field against the experimental flow visualization performed by Piziali (NASA TM-4632) and they plan to submit it to the AIAA Fluid Dynamics Conference in June 2009.

"The success of our results applied to one rotor wing will help us to understand the next step of our approach to the entire four-bladed rotor in forward fight conditions," says Dumlupinar. "Our ultimate goal is predicting an entire flow field of a helicopter in forward flight."

-Ercan Dumlupinar, Syracuse University, with Anne Heavey, iSGTW

NYSGrid uses the Open Science Grid middleware, and all its sites are available to the OSG Engagement VO; some are available to other VOs as well. The nodes at its CCR site in Buffalo are available to all OSG users.

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