Numerical Investigation On Aircraft Ditching's Characteristic Of Motion By FVM

As the widespread application of large aircrafts, the extended overwater operation of the aircraft becomes more and more frequent, hence raising the risk and the possibility of crash during the ditching process. Recent years, there are more and more reports about the aircraft ditching and plane crash happening all around the world, which makes the aircraft ditching problems become an active and important issue, again. The safety performance of aircraft ditching has been not only treated as a key criterion when awarding airworthiness certificate by domestic and oversea aerospace department, and also performed as an important position in air worthiness regulation of Europe and United States. In order to ensure the success of aircraft ditching, we need to comprehend the motion details of the aircraft by analyzing the dates, including the attitude, speed, water impact load, and the water pressure, so as to provide guidance for aircraft design taking account of ditching.Numerical simulation method is a practical and widely recognized approach to simulate the aircraft ditching, since it has been utilized by many investigators in their researches, yet also been well developed. To simulate the aircraft ditching, we can get the change of attitude angle and speed of the plane, water impact load and the distribution of the bottom pressure. Through the analyses of those data, we can give some guidance on the aircraft ditching.In this work, the numerical simulation based on Finite Volume Method (FVM) has been carried out to investigate the mechanical properties of the aircraft while ditching. Considering problems involved by free water surface, Volume of fluid (VOF) method is introduced to cope with two phase flow between the air and the water, thus the air damping could be represented and taken account in our observation. The main content is as follows:1. Consulting the relevant literature, numerical calculus model is constructed, including fuselage and fluid domain one. The latter one is consisted of air and water.2. VOF method is used to dispose the two-phase flow problem between air and water, so as to present the state of the airplane wrapped in water and air during the aircraft ditching. Dynamic mesh method is used to deal with the remesh, while six DOF method to control the fuselage, so external force and moment can be adequate considered during the simulation process.3. Numerical simulation is carried out using commercial software FLUENT, to investigate the motion behavior of the aircraft A320in ditching process. Data including the attitude, speed, water impact load, and the distribution of the water pressure is derived and analyzed accounting of the state variation of motion and stress.4. Results of different cases are analyzed and compared, varied by the initial attitude before ditching. Our focus concentrates on the influence on the maximum of the water pressure and attitude angle affected by the entry attitude, which demonstrate the fact that the numerical simulation of aircraft ditching by FVM can be good reference to the aircraft ditching.