Computer-aided method for a cost-optimized calculation of aerodynamic forces on an aircraft
View Patent ↗A computer-aided method suitable for assisting in the design of an aircraft by providing the values of dimensional variables, dependant of a predefined set of parameters, for the complete aircraft or an aircraft component, comprising the following steps: a) Defining a parametric space grid; b) Obtaining a suitable Reduced Order Model (ROM) model, particularly a Proper Orthogonal Decomposition (POD) model, for calculating said variables for whatever point over the parametric space through an iterative process. Computer Fluid Dynamics (CFD) is used to calculate said variables for an appropriately selected set of points over the parametric space, which are used to approximate, via ROM and ad hoc interpolation, the variables in any other point over the parametric space. The method minimizes the required number of CFD calculations (to minimize the computational cost, which dramatically depends on this number) for a given level of error.
1. A computer-aided method for assisting in the design of an aircraft by providing the values of one or more dimensional variables for the complete aircraft or an aircraft component, said one or more variables being dependant on a predefined set of parameters, said method comprising the following steps at least one of which is carried out on a computer processor:
a) Defining a parametric space grid setting predetermined distances between its values;
b) Obtaining a model for calculating said one or more dimensional variables for whatever point over the parametric space grid through an iterative process with respect to a reduced group of points, of increasing number of points in each iteration, comprising the following sub-steps:
bl) Calculating the values of said one or more dimensional variables for an initial group of points using a CFD model;
b2) Obtaining an initial ROM model from said CFD computations and calculating the values of said one or more dimensional variables for said initial group of points using the initial ROM model;
b3) Establishing a group with the largest deviation ε between the results provided by the CFD and the ROM models, selecting the e-point thereof and finishing the iterative process if ε is less than a predefined value ε 0 ;
b4) Selecting new points over the parametric space grid to be added to the group of points established in step b3) as those points placed inside the parametric space grid at a predefined distance from said e-point;
b5) Calculating the values of said one or more dimensional variables for the new points using the CFD and the ROM models and going back to sub-step b3).
2. A computer-aided method according to claim 1 , wherein said complete aircraft or an aircraft component is divided into blocks and said CFD and ROM models are applied block by block.
3. A computer-aided method according to claim 1 , wherein said one or more dimensional variables includes one or more of the following: aerodynamic forces, skin values, and values distribution around the complete aircraft or aircraft component.
4. A computer-aided method according to claim 1 , wherein said predefined set of parameters includes one or more of the following: angle of attack, and Mach number.
5. A computer-aided method according to claim 1 , wherein said aircraft component is one of the following: a wing, a horizontal tail plane, and a vertical tail plane.
6. A computer-aided method according to claim 1 , wherein said ROM model is a POD model.
7. A computer-aided method according to claim 6 wherein the deviation ε between the results provided by the CFD and the POD models is obtained as the root mean square error between said results.
8. A computer-aided method according to claim 6 , wherein the POD model used is obtained by eliminating the less relevant modes of the group of points.