Development of a smoothed particle hydrodynamics method and its application to aircraft ditching simulations

Abstract

The present study addresses the development and validation of a smoothed particle hydrodynamics (SPH) method, particularly to examine its feasibility and capability in hydrodynamics and dynamics of aircraft during ditching. The developed method solves the weakly compressible Navier-Stokes equations coupled with six-degree of freedom dynamics to achieve an accurate prediction of the interaction between the aircraft and the fluid. In this SPH method, a dummy particle wall-boundary condition is automatically implemented to meet the requirement of application on geometrically complex engineering problems. An efficient particle search strategy merging the ideal of Cell-linked list with Vertlet list is proposed to speed up the neighbor particles search process. The present SPH method uses an OpenMP memory-shared parallelization in conjunction with Z-curve reordering to accelerate the computation. Validations have been performed on several classic hydrodynamic problems, where good agreements were achieved via comparing with documented experimental results. The developed SPH method is applied to predict the ditching event of a complex helicopter model. Results demonstrate the ditching process, indicating that the method can be potentially used in aircraft ditching applications.

Simulations of helicopter ditching using smoothed particle hydrodynamics

“…This finally results in an opposite momentum, leading to a strong increase of the pitch angle in phase 3. This nose-down nose-up pitching motion was already observed in the simulations of Xiao et al [9] .…”

“…A numerical study is performed with the SPH method, a good candidate for such complex numerical simulations thanks to its meshless and Lagrangian features and its ability to deal with complex geometries and large body motions in interaction with a free surface submitted to strong deformations [4][5] . Some simulations of helicopter ditching using the smoothed particle hydrodynamics (SPH) method have already been performed in the past [6][7][8][9] . Among these works, Xiao et al [9] investigated the ditching in calm water of an helicopter impacting with three different pitch angles highlighting a nose-down nose-up pitching motion.…”

“…Some simulations of helicopter ditching using the smoothed particle hydrodynamics (SPH) method have already been performed in the past [6][7][8][9] . Among these works, Xiao et al [9] investigated the ditching in calm water of an helicopter impacting with three different pitch angles highlighting a nose-down nose-up pitching motion. The present paper covers also this aspect, investigating the pitch angle evolution in time and its effects on the resulting flow, hydrodynamic forces and helicopter behavior, with and without waves.…”

Crashworthy design and energy absorption mechanisms for helicopter structures: A systematic literature review

“…Xiao et al [250] developed a weakly compressible SPH method coupled with six-degree-of-freedom dynamics to investigate the hydrodynamic and dynamic behavior of a helicopter ditching. A simple dummy particle wall boundary treatment method was used to address the geometrically complex engineering problems, and an OpenMP memory-shared parallelization integrated with Z-curve particle reordering was implemented to accelerate the computation.…”

Unsteady Detached-Eddy Simulation (DES) of the Jetstream 31 aircraft in One Engine Inoperative (OEI) condition with propeller modelling

“…Since, unsteady flow problems are in the centre of research interest for aerospace applications, see, e.g., in the works of Jacquin et al [22], Huang and Ekici [23], Ghoreyshi et al [24], and Ghoreyshi and Cummings [25], therefore, the concept of the DES approach offers a potential possibility to investigate unsteady flow around an aircraft. Further CFD investigations in conjunction with the DES technique were carried out recently by Bunge et al (2007) [26] Aircraft simulations and flight testing are playing a key role to support our understanding of flight physics and aerodynamics [11,[35][36][37][38][39][40]. Therefore, several experimental and computational aerodynamics studies on the Jetstream 31 aircraft (see Figure 1) have been carried out in the National Flying Laboratory Centre (NFLC) at Cranfield University in the last decade.…”