The overall technical objective of the Phase II effort is to make OVERFUN as a fully multi-functional aeroelastic software system that can establish either the discrete time state-space plant model or the frequency-domain aeroelastic equation of motion with three embedded unsteady aerodynamic sub-systems; due to the structural deformation, the control surface deflection and the discrete gust excitation, respectively. All three unsteady aerodynamic sub-systems can be obtained by applying the extended complex variable differentiation (CVD) technique to the complex version of FUN3D, referred to as FUN3D-CVD, to generate the numerically exact linearized unsteady aerodynamic forces. As a wrapper around the steady Navier-Stokes (N-S) solver of FUN3D for trim analysis with static aeroelastic effects as well as a wrapper around the complex unsteady N-S solver of FUN3D-CVD for generating the three unsteady aerodynamic sub-systems, OVERFUN can establish a very accurate time-domain plant model or frequency-domain aeroelastic equation of motion that can capture all essential flow physics on a statically deformed aeroelastic model.
To showcase that the OVERFUN generated plant model can be directly adopted by the modern control law design schemes for control system design, a classical and a robust flutter suppression and gust load alleviation control systems will be generated for the Benchmark Active Controls Technology wing with trailing edge flap as input as well as with the upper spoiler as input. A twin-engine transport flutter model (TETFM) that was tested by the Boeing engineers in the Transonic Dynamics Tunnel (TDT) will be selected as the test case to demonstrate the accuracy of the OVERFUN predicted aeroelastic solution for complex configuration by the validation with the TDT measured flutter boundary of the TETFM.
The outcome of the Phase II effort will be a production-ready OVERFUN software system for commercialization in Phase III.
The proposed effort is highly relevant to on-going and future NASA fixed wing projects, which involve innovative design concepts such as the Truss-Braced Wing, Blended Wing Body, and Supersonic Business Jet. The proposed work will offer a computational tool to the NASA designers for early exploration of design concepts that exploit the trade-off between the passive and active approaches for mitigating the potential aeroelastic problems associated with those configurations.
The proposed discrete time state-space plant model generation can be applied to various flight vehicles including blended wing-bodies, joined wings, sub/supersonic transports, morphing aircraft, and similar revolutionary concepts being pursued. The proposed research will be needed for designing the next generation of civil and military aircraft to meet the stringent future performance goals.