PROJECT TITLE: A Nonlinear Volterra Kernel Identification System for Aeroelastic Applications
TECHNICAL ABSTRACT (LIMIT 200 WORDS)
Nielsen Engineering & Research (NEAR) is proposing to develop an innovative Volterra kernel identification tool suitable for aeroelastic analysis from wind-tunnel or flight test data. Aeroelastic studies play a critical role in aircraft safety and design and, to accelerate the design process and reduce life cycle costs, nonlinear aerodynamic effects must be considered from the onset. The Volterra theory of nonlinear systems provides a mathematically rigorous approximation technique to describe these unsteady aerodynamic effects. A critical problem, however, is the difficulty of identifying the Volterra kernels. The proposed innovation is a time-domain Volterra kernel identification method which uses physically realizable inputs, is robust with respect to noise, and minimizes or eliminates the need for analytical assumptions. During the Phase I program, NEAR will implement the second-order version of the method and demonstrate its accuracy, robustness, and extendibility to higher-order kernels. Successful completion of the Phase I objectives will lead, in Phase II, to the development of an operational Volterra series identification and prediction tool. The resulting technology will provide a rational means of simulating nonlinear aerodynamic behavior in multidisciplinary analyses and will facilitate the incorporation of high fidelity tools into the preliminary design phase of aerospace vehicles.
POTENTIAL COMMERCIAL APPLICATIONS
The proposed nonlinear identification system provides a unique capability that will extend the usefulness of wind-tunnel and flight test data by producing compact, reduced order models of unsteady nonlinear aerodynamic effects in aeroelastic analyses. The formulation of reduced order models in aeroelasticity is important for several reasons: (1) cost reduction and speed up of preliminary design cycles, (2) understanding of nonlinear behavior and elimination of later "surprises," and (3) real-time aeroservoelastic control applications. In addition, the market for efficient aeroelastic analysis tools in the next few years is expected to become significant because: (a) aeroelastic analyses are needed for every aerospace vehicle (aircraft, missile, or reusable launch vehicle), (b) as a consequence of aircraft modifications and expanded/changing missions, aging aircraft fleets throughout the world will require not one, but multiple aeroelastic analyses over time, and (c) small and mid-size companies will, increasingly, be required to perform such analyses on a routine basis for aircraft retrofits. These facts (necessity of aeroelastic analyses, multiplicity of such analyses over time, and anticipated "decentralization") all converge towards the establishment of a sizeable market for efficient analysis tools, of which NEAR's offering is a good example.
NAME AND ADDRESS OF PRINCIPAL INVESTIGATOR
Patrick H. Reisenthel
Nielsen Engineering & Research, Inc.
526 Clyde Avenue
Mountain View , CA 94043-2212
NAME AND ADDRESS OF OFFEROR
Nielsen Engineering & Research, Inc.
526 Clyde Avenue
Mountain View , CA 94043-2212