NASA SBIR 2005 Solicitation


SUBTOPIC TITLE:Aircraft Systems Noise Prediction and Reduction
PROPOSAL TITLE:Computational Aeroacoustics Using the Generalized Lattice Boltzmann Equation

SMALL BUSINESS CONCERN (Firm Name, Mail Address, City/State/Zip, Phone)
209 W. Alamar Ave, Suite A
Santa Barbara, CA 93105-3701
(805) 682-5766

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
Kannan N Premnath
209 W. Alamar Ave, Suite A
Santa Barbara, CA  93105-3701
(805) 682-5766

TECHNICAL ABSTRACT (Limit 2000 characters, approximately 200 words)
The research proposed targets airframe noise (AFN) prediction and reduction. AFN originates from complex interactions of turbulent flow with airframe components that are extremely difficult to compute efficiently and accurately. In Phase I the feasibility of an innovative generalized lattice Boltzmann equation (GLBE) approach as a computational aeroacoustics (CAA) tool was evaluated. A subgrid scale (SGS) with wall damping was introduced into the GLBE to enable large eddy simulations. GLBE results on wall turbulence statistics compared well with direct numerical simulations and experiments. The GLBE approach, which uses multiple relaxation times, was significantly more stable than, and as computationally efficient as, the more common single-relaxation time LBE at high Reynolds numbers. It was also computationally competitive with finite-difference methods on single processors, but GLBE had the major advantage of scaling near-linearly on large parallel computers. GLBE computations also accurately reproduced the tonal frequencies for cross-flow over a single, and a pair of cylinders, and feedback-generated tonal frequencies for flow over cavities, which are CAA benchmarks for AFN. With feasibility demonstrated in Phase I, further developments of GLBE, including innovative use of wall-layer models, dynamic SGS models, improved boundary condition implementation and grid refinement strategies in Phase II would enable simulations of very high Reynolds number CAA problems of complex geometry with high fidelity. The GLBE approach developed will then be interfaced to an existing far-field acoustics prediction code to efficiently address AFN in configurations of interest, including high-lift systems and landing gear.

POTENTIAL NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
The proposed GLBE approach for computational aeroacoustics will be applicable for high Reynolds number flows over structures with complex geometrical shapes. These include noise prediction from airframe structures such as landing gear, flaps and slats during take-off and landing. The approach is also well suited for acoustic analysis of aircraft internal systems. In addition to prediction of noise, the computational package would also be applicable to computational fluid dynamics of low Mach number flows in aircraft systems.

POTENTIAL NON-NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
The potential applications include prediction of noise from a variety of transportation systems, e.g. automobiles and trains, and HVAC systems. For accurate prediction of noise generation in such systems due to turbulence-structure interactions, the same technology as that for AFN is required. Current commercial packages cannot adequately handle the unsteady turbulence field which requires a high degree of parallelizability and capability to represent turbulence by dynamic models in complex geometries. The extended GLBE approach would be developed to handle these issues and could penetrate this market rapidly.

NASA's technology taxonomy has been developed by the SBIR-STTR program to disseminate awareness of proposed and awarded R/R&D in the agency. It is a listing of over 100 technologies, sorted into broad categories, of interest to NASA.

Structural Modeling and Tools

Form Printed on 07-25-06 17:04