Numerical Simulation of Aircraft Ditching of a Generic Transport Aircraft: Implementation of an Aerodynamic Model

Abstract

Aircraft certification requires the analysis of water emergency landing (ditching) with respect to passenger safety. In order to support the design and certification processes, models for numerical simulation of aircraft ditching are being developed. Following the work developed in the SMAES project (SMart Aircraft in Emergency Situations, 2011-2014), which consisted in the enhancing of simulation capabilities for aircraft ditching analysis, DLR is transferring the acquired knowledge to full-scale aircraft ditching. Due to the complexity involved in fullscale modeling, a pre-processing tool is currently under development for an automatic model generation of full-scale aircraft ditching models for the explicit solver Virtual Performance Solution (VPS). The overall goal of this work is to implement and validate an aerodynamic model in the numerical simulation to allow an improvement in the state of the art of full-scale aircraft ditching. The developed model physically calculates the loads with proper aerodynamic equations and strongly improves the predictability of loads occurring during a ditching simulation. For the implementation of the aerodynamic model in the numerical simulation, the creation of a new module in the pre-processing tool is proposed. The aerodynamic calculation of lift, drag and pitch moment, based on the evolution of the angle of attack and ight velocity, is accomplished with the implementation of an external user subroutine within the numerical simulation. The superiority of the developed aerodynamic model over the state of the art is demonstrated based on comparison of results of sensitivity and parameter studies.