Applications
Applications
Principal Investigator: Yehia M. Rizk (NASA Ames Research Center)
Co-Investigators: Ken Gee (MCAT), Ferhat Hatay(MCAT), Jahed Djomehri(CALSPAN)
The objective of this work is to integrate an overset Navier-Stokes flow solver with a modal structural code to computationally determine the effects of aeroelasticity on the aerodynamic characteristics of aircraft using massively parallel computers.
A modal structural code was integrated into the OVERFLOW code, which solves the Navier-Stokes flow equations using overset grids to model the geometry. The initial development centered on the PVM version of the parallel OVERFLOW code. With the development of an MPI version of OVERFLOW, an MPI version of the aeroelastic code was developed as well.
Arrow-wing-body tip deflection convergence history.
A new MPI version of a parallel, overset, aeroelastic code (OVERAERO) was developed based on the OVERFLOW and modal structures codes. The OVERAERO code can compute the aeroelastic deformation of a surface due to the aerodynamic loads generated by the surface. Multiple structural surfaces can be computed for a given geometry, each with its own modal data set. Rigid structures attached to a flexible surface, such as a nacelle attached to a wing, are moved according to the deflection of the attachment region on the flexible surface. Flexible surfaces, for which no modal data are available, such as a slat or flap attached to a wing, can be deflected by assuming the deformation mirrors the wing deformation.
Both coupled and uncoupled versions of OVERAERO were developed. In the coupled version, the surface deflection is computed after every flow iteration. In the uncoupled version, the OVERFLOW code is used to compute a flow solution, the flow solution is used as input into a standalone structures code, and the new deflected geometry is fed back into OVERFLOW for further flow computation. The newly developed codes were tested using an arrow-wing-body geometry and compared with results from the ENSAERO patched aeroelastic code. The results, shown in Fig. 1, indicated all versions of the OVERAERO code produced similar results as the patched code.
Development of the OVERAERO code will allow airframe designers to predict the effects of aeroelastic deformation on current and new aircraft designs using overset grids. The use of overset grids reduces the amount of time required to generate a grid system to model a complex geometry, such as a full aircraft with high-lift surfaces. This will serve to reduce development costs and lead to more efficient and safer aircraft.
The MPI version of OVERAERO will be used to compute the static aeroelastic solution of a high-wing transport aircraft on the new HPCC testbed. The computation will showcase the new code and the ability of current massively parallel computers to handle a large-scale aircraft computation.
Gee, K., and Rizk, Y., "OVERAERO-MPI: Parallel Overset Aeroelasticity Code," HPCC/CAS Workshop, NASA Ames Research Center, Moffett Field, CA, August 25-27, 1998.
Hatay, F. F., Jespersen, D. C., Guruswamy, G. P., Rizk, Y. M., Byun, C., and Gee, K., "A Multi-level Parallelization Concept for High-fidelity Multi-block Solvers," SC97: High Performance Networking and Computing, San Jose, CA, November, 1997.
Yehia M. Rizk
NASA Ames Research Center
rizk@nas.nasa.gov
650-604 4466