Maneuver Simulation of a Flexible Transport Aircraft with HiFi-Methods and Comparison to Experimental Data

Abstract

A crucial issue in the development process of a modern jet transport aircraft is the comprehensive evaluation of its flight characteristics. Traditionally this requires extensive and costly flight tests including dedicated maneuvers for the development of a mathematical model via system identification. However, future aircraft designs must be characterized by increased time and cost reductions. Approaches for the replacement of flight tests therefore are of paramount importance in current research activities of aeronautical academia and industry. With the advent of sophisticated methods (CFD and CSM) for the detailed multidisciplinary simulation of complex aircraft configurations even in flight regimes characterized by compressible and viscous effects, the virtual flight test can be expected to yield results with accuracies close to the real flight test. This approach is currently followed in work package 3 of the DLR project VicToria. The goal is to establish the virtual flight test in order to significantly reduce development costs by decreasing the number of actual flight tests. Furthermore, the system identification process can already be started in the preliminary design process of the aircraft and enables its characterization at an early stage of the design. The virtual flight test proposed in this work corresponds to a multidisciplinary simulation based on high-fidelity methods for the involved disciplines. Aerodynamic forces are calculated in the time domain by CFD to account for nonlinearities; as for the flight dynamics, the governing equations of nonlinear rigid-body motions are applied. The structural flexibility of the airframe plays a decisive role for the flight dynamics, especially in maneuvers with higher loadings (e.g. 2.5 g load factor in pull-up) and is thus considered in the simulation approach. To ensure acceptable computing times, the simulations are performed massively parallel using a proper framework, where the multidisciplinary methods and processes developed in the predecessor project Digital-X are employed and extended. The test case of this work is the Airbus A320. A number of simulation models for the involved disciplines were either build from scratch (e.g. a CAD geometry representing the outer shape and the computational grid for the CFD simulations) or provided by the manufacturer (finite element model). Results of unsteady symmetric tail input maneuvers are presented for different levels of excitation. Selected results will be compared with data from flight tests.