Efficient Supersonic Air Vehicle Preliminary Conceptual Multi-Disciplinary Design Optimization Results

Multidisciplinary Design Optimization of Aerial Vehicles: A Review of Recent Advancements

“…In the conceptual design stage, it is common to use simple and fast aerodynamic predictions which can be provided by empirical equations [24,28] or panel methods [33,34]; however, in cases where more detailed insights into the design are required, it is often shown that computational fluid dynamics (CFD) codes can be a more accurate and hence suitable alternative [35,36]. Similarly, in the initial design phases, the weight and balance are estimated by using empirical equations [24,37] as well as statistical data [38,39], while for additional fidelity, it is also possible to augment the calculations by using the results of simplified [40][41][42] or full [33,43] structural analyses. In this respect, the assessment of the structures is typically relevant only in detailed design applications where increased fidelity is required [32,44], and for that reason, the models are built by using advanced computational structural mechanics (CSM) simulations and by considering an extensive list of structural elements and parameters [35,[45][46][47].…”

“…To this date, the structural analyses are solely focused on the wing [27,36], and their main advantage within a MDO framework is that they can be used either to directly calculate the strength [27,44] or to provide additional data for further static as well as dynamic aeroelastic computations [48,49]. Finally, the propulsion specifications can be expressed in high-fidelity applications through a dedicated simulation model that considers the entire [12,17,26,[50][51][52][53] or an isolated part [38,54,55] of the engine's operation, but for faster optimizations, it is also efficient to use statistical approximations [43,45] or "rubberized" engines by means of scaling factors [16,32,56].…”

“…On the downside, such complex integration can pose a number of challenges for the MDO process, and in fact, it can be seen that there is no obvious figure of merit that can be used as an objective, while at the same time, it is often necessary to perform numerous, and possibly unaffordable, analyses in order to cover the entire flight envelope [28]. To this end, the coupling between aerodynamics, structures, and flight mechanics has shown very promising results for the overall design quality [29,33,36,76,77], and the most notable methods of integration include the decomposition of the mission into different segments [28], the alleviation of loads through aeroservoelastic optimization [51,75], the exploration of innovative control configurations [43,78], and the assessment of handling qualities through the incorporation of military standards [28,67,78].…”

“…A common application of metamodels is to substitute the high-fidelity models and therefore increase the speed of the optimization while allowing for a larger set of design points to be considered in the process [30]. In total, metamodels have typically been used to replace complex aerodynamic [31,37,41,46,90,91,94,95,114], as well as structural [31,32,43,51,90,91,95] analyses such as CFD and CSM codes, and it has been shown that this approach can generally be a viable alternative at a minimum loss of accuracy. Similarly, metamodels can also effectively represent other complex elements of the framework, and in fact, they have been successfully implemented to estimate the dynamics of the aircraft systems [83,84], the performance of the engine and the exhaust [12,13,17,51], the noise and the ground boom…”

“…In general, the medium-fidelity tools are solutions which aim to provide sufficiently accurate results at a reasonable computational expense, and to this end, the main trend here is to either implement more refined low-fidelity simulations or to rely on a simplified highfidelity analysis. This can be clearly seen in the case of aerodynamics as well as structural analysis, where a common approach is to use Euler solvers [43,63], higher-order panel codes [12,59], or coarse CFD simulations [97] in the first and global CSM analyses [43] or simplified geometries [40,45] in the second. For this phase of the development process, the estimation of the weight and the mission analysis are also based on more advanced computational tool packages which offer a number of sizing alternatives [12,61], while the engine performance is calculated by means of simple one-dimensional simulations that can evaluate the thrust and the consumption at a variety of flight conditions [20,38].…”