Geometry definition and grid generation for a complete fighter aircraft

Recent advances in computing power and numerical solution procedures have enabled computational fluid dynamicists to attempt increasingly difficult problems. In particular, efforts are focusing on computations of complex three-dimensional flow fields about realistic aerodynamic bodies. To perform such computations, a very accurate and detailed description of the surface geometry must be provided, and a three-dimensional grid must be generated in the space around the body. The geometry must be supplied in a format compatible with the grid generation requirements, and must be verified to be free of inconsistencies. This paper presents a procedure for performing the geometry definition of a fighter aircraft that makes use of a commercial computer-aided design/computer-aided manufacturing system. Furthermore, visual representations of the geometry are generated using a computer graphics system for verification of the body definition. Finally, the three-dimensional grids for fighter-like aircraft are generated by means of an efficient new parabolic grid generation method. This method exhibits good control of grid quality

Experimental testing of tape springs folded in three dimensions

One of the main drivers in satellite design is the minimization of mass, in the attempt to reduce the large costs involved in the launch of the spacecraft. However, the recent advances in micro electro mechanical systems (MEMS) have allowed a further reduction in the mass of on-board equipment. With advances in micro ion propulsion systems for attitude control, and the miniaturisation of ground based mobile communications, the satellite power requirement does not reduce linearly with mass. This creates the need for photovoltaic cell areas larger than the surface area of the satellite bus. Therefore small satellite deployable structures become increasingly important. The major design requirements for such systems are reliability and low cost. The simpler the components of the system are (i.e. the minimum number of moving parts, lubrication etc), the more chance of the system meeting the design requirements. For this reason, there has been significant investigation into the deployment dynamics of tape springs folded in two dimensions, to form simple hinges which do not require lubrication and automatically locks in the deployed configuration. The present work focuses on using tapes springs to support a new conceptual area deployment design for nano/micro satellites. The deployment of this design incorporates bi-axial folding, which requires the tape springs to unfold in three dimensions. Little research has been carried out in this area. The design of a test rig to determine the properties of this three dimensional deployment is presented in detail. This rig measures both the bending and twisting moments produced from the three- dimensional fold. The combination of these two moments defines the main deployment properties of the tape springs and hence the final array. The experimental results will be compared to theoretical results produced using shell theory and non- linear, finite element analysis

Development of an explicit multigrid algorithm for quasi-three-dimensional viscous flows in turbo-machinery

A rapid quasi three-dimensional analysis was developed for blade-to-blade flows in turbomachinery. The analysis solves the unsteady Euler or thin layer Navier-Stokes equations in a body-fitted coordinate system. It accounts for the effects of rotation, radius change, and stream-surface thickness. The Baldwin-Lomax eddy-viscosity model is used for turbulent flows. The equations which are solved by a two-stage Runge-Kutta scheme made efficient by use of vectorization, a variable time-step, and a flux-based multigrid scheme, are described. A stability analysis is presented for the two-stage scheme. Results for a flat-plate model problem show the applicability of the method to axial, radial, and rotating geometries. Results for a centrifugal impeller and a radial diffuser show that the quasi three-dimensional viscous analysis can be a practical design tool

Three-dimensional aerodynamic shape optimization using discrete sensitivity analysis

An aerodynamic shape optimization procedure based on discrete sensitivity analysis is extended to treat three-dimensional geometries. The function of sensitivity analysis is to directly couple computational fluid dynamics (CFD) with numerical optimization techniques, which facilitates the construction of efficient direct-design methods. The development of a practical three-dimensional design procedures entails many challenges, such as: (1) the demand for significant efficiency improvements over current design methods; (2) a general and flexible three-dimensional surface representation; and (3) the efficient solution of very large systems of linear algebraic equations. It is demonstrated that each of these challenges is overcome by: (1) employing fully implicit (Newton) methods for the CFD analyses; (2) adopting a Bezier-Bernstein polynomial parameterization of two- and three-dimensional surfaces; and (3) using preconditioned conjugate gradient-like linear system solvers. Whereas each of these extensions independently yields an improvement in computational efficiency, the combined effect of implementing all the extensions simultaneously results in a significant factor of 50 decrease in computational time and a factor of eight reduction in memory over the most efficient design strategies in current use. The new aerodynamic shape optimization procedure is demonstrated in the design of both two- and three-dimensional inviscid aerodynamic problems including a two-dimensional supersonic internal/external nozzle, two-dimensional transonic airfoils (resulting in supercritical shapes), three-dimensional transport wings, and three-dimensional supersonic delta wings. Each design application results in realistic and useful optimized shapes

Insight into High-quality Aerodynamic Design Spaces through Multi-objective Optimization

An approach to support the computational aerodynamic design process is presented and demonstrated through the application of a novel multi-objective variant of the Tabu Search optimization algorithm for continuous problems to the aerodynamic design optimization of turbomachinery blades. The aim is to improve the performance of a specific stage and ultimately of the whole engine. The integrated system developed for this purpose is described. This combines the optimizer with an existing geometry parameterization scheme and a well- established CFD package. The system’s performance is illustrated through case studies – one two-dimensional, one three-dimensional – in which flow characteristics important to the overall performance of turbomachinery blades are optimized. By showing the designer the trade-off surfaces between the competing objectives, this approach provides considerable insight into the design space under consideration and presents the designer with a range of different Pareto-optimal designs for further consideration. Special emphasis is given to the dimensionality in objective function space of the optimization problem, which seeks designs that perform well for a range of flow performance metrics. The resulting compressor blades achieve their high performance by exploiting complicated physical mechanisms successfully identified through the design process. The system can readily be run on parallel computers, substantially reducing wall-clock run times – a significant benefit when tackling computationally demanding design problems. Overall optimal performance is offered by compromise designs on the Pareto trade-off surface revealed through a true multi-objective design optimization test case. Bearing in mind the continuing rapid advances in computing power and the benefits discussed, this approach brings the adoption of such techniques in real-world engineering design practice a ste

A storied surface

A Storied Surface is an exploration of narrative based graphic design engineered for textile surfaces. Beginning with an experiment involving the characters of the novel Matilda, I developed a design system. My process involves creating narratives and illustrating the characters. Then the illustration is abstracted. The abstraction is used to create prints. Finally, all of the elements including the original illustration, abstraction, and print are used to create engineered designs for three-dimensional surfaces. Advances in digital textile printing and the increasing implementation of graphic textiles in the fashion industry led me to experiment with applying my own design to textiles surfaces. Through the creation of my own narratives, I refined my design system and reached a solution for three-dimensional application involving digital textile printing. The conclusion resulted in the creation of engineered prints applied to textile surfaces, which express my own narratives about the people and places of Provence, Côte d\u27Azur, and Toscana