Phase II Final Report - NASA's Institute for Advanced Concepts
Phase II Final Report - NASA's Institute for Advanced Concepts
Phase II Final Report - NASA's Institute for Advanced Concepts
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Planetary Exploration Using Biomimetics<br />
An Entomopter <strong>for</strong> Flight on Mars<br />
expensive to simulate on Earth. Additionally, the fundamental basis of the Navier-Stokes equations<br />
(Reynolds-averaged) tightly couples CFD to physics.<br />
The ability to acquire the data from the time history of unsteady <strong>for</strong>ces and vortex <strong>for</strong>mation on<br />
the wing is extremely important and has been demonstrated in this report. The Entomopter vehicle<br />
design hinges on whether or not the wings can generate sufficient lift and have an acceptable<br />
lift-to-drag ratio.<br />
This section will address computations with the CFD codes WIND and FLUENT, as well as<br />
codes from Metacomp Technologies, Inc., presented in chronological order. Three-dimensional<br />
cases with blowing were simulated initially using WIND to determine if aerodynamic per<strong>for</strong>mance<br />
can be enhanced by surface blowing. Cases showing the effect of blowing tangential to<br />
the trailing edge surface are presented. Animations of the resulting flow fields show the effect of<br />
blowing. A major part of the ef<strong>for</strong>t at the University of Missouri-Rolla (UMR) with FLUENT<br />
has been to design the airfoil section and the 3D plan<strong>for</strong>m to mimic the aerodynamic attributes<br />
of a typical insect wing. A cicada wing was analyzed <strong>for</strong> its aerodynamic parameters, such as<br />
camber, thickness, plan<strong>for</strong>m, structural attributes, and role of the hind wing. Extensive literature<br />
review was conducted on the aerodynamic aspects of insect flight and the current status of<br />
insect-derived MAV design. A series of two-dimensional studies was conducted using FLUENT<br />
to optimize airfoil section parameters, such as thickness and camber, and to establish leading<br />
edge vortex (LEV) behavior. Reynolds number was varied by a factor of 10, and the resulting<br />
flow fields have been analyzed. A small thickness, cambered three-dimensional wing was<br />
designed <strong>for</strong> the work in progress on flapping wing simulations. Understanding low Reynolds<br />
unsteady aerodynamics and controlling wing kinematics during the stroke cycle have been identified<br />
as key topics <strong>for</strong> the continuing Entomopter CFD work.<br />
3.3.1.2 Entomopter Wing CFD Analysis: WIND<br />
Preliminary CFD calculations were conducted with WIND Version 3 Code [283], a product of<br />
the NPARC Alliance, a partnership between NASA Glenn Research Center (GRC) and Arnold<br />
Engineering Development Center (AEDC) dedicated to the establishment of a national, applications-oriented<br />
flow-simulation capability. WIND solves the Reynolds-averaged Navier-Stokes<br />
equations, along with supporting equation sets governing turbulent and chemically reactive<br />
flows.<br />
Calculations with WIND were completed early in the project to get some idea of the complexity<br />
and physics associated with a sinusoidally oscillating airfoil with tangential blowing. Although<br />
the sinusoidal flapping motion did not physically represent the actual motion of the Entomopter<br />
wing, purely sinusoidal flapping runs were important in understanding basic vortex creation and<br />
convection over the airfoil, which ultimately drives the aerodynamics and wing lift.<br />
Both steady and unsteady computations with an oscillating inflow and blowing (mass ejection at<br />
the wing tips) were completed to assess the code's ability to handle this very demanding flow<br />
field, which includes a very low Mach number inflow, with sinusoidal oscillation to simulate<br />
flapping motion, and mass ejection on the outer wing panels to simulate blowing. Blowing is<br />
used to entrain lower energy boundary-layer air and reenergize it with higher energy air,<br />
decreasing the tendency <strong>for</strong> the flow to separate and thereby increasing circulation. This, along<br />
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<strong>Phase</strong> <strong>II</strong> <strong>Final</strong> <strong>Report</strong>