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Computational fluid dynamics (CFD)/computational structural dynamics (CSD) coupling analysis is an important method in the research of helicopter aeroelasticity due to its high precision. However, this method still suffers from some problems, such as wake dissipation and large computational cost. In this study, a new coupling method and a new air load correction method that combine the free wake model with the CFD/CSD method are proposed to maintain computational efficiency whilst solving the wake dissipation problem of the prior coupling methods.

A new coupling method and a new air load correction method that combine the free wake model with the CFD/CSD method are proposed. With the introduction of the free wake model, the CFD solver can adopt two-order accuracy schemes and fewer aerodynamic grids, thus maintaining computational efficiency whilst solving the wake dissipation problem of the prior coupling methods.

Compared with the predictions of the prior methods and flight test data, those of the proposed method are more accurate and closer to the test data. The difference between the two methods in high-speed forward flight is minimal.

Because of the chosen research approach, the research results may lack generalisability. Therefore, researchers are encouraged to test the proposed method further.

In this paper, a CFD/CSD/free wake coupling method is proposed to improve the computational accuracy of the traditional CFD/CSD coupled method and ensure the computational efficiency.

The purpose of this paper is to introduce a novel method to study the flutter coupling mechanism of the twin-fuselage aircraft, which is becoming a popular transportation vehicle recently.

A new method of flutter mode indicator is proposed based on the principle of work and power, which is realized through energy accumulation of generalized force work on generalized coordinates, based on which flutter coupling mechanism of the twin-fuselage aircraft is studied using ground vibration test and computational fluid dynamics/computational solid dynamics method.

Verification of the proposed flutter mode indicator is provided, by which the flutter mechanism of the twin fuselage is found as the horizontal tail’s torsion coupled with its bending effect and the “frequency drifting” phenomenon of twin-fuselage aircraft is explained logically, highlighting the proposed method in this paper.

This paper proposed a new method of flutter mode indicator, which has advantages in flutter modes indexes reliability, clear physical meaning and results normalization. This study found the flutter coupling mechanism of twin-fuselage aircraft, which has important guiding significance to the development of twin-fuselage aircraft.

The purpose of this paper is to advance the multiphysics analysis of helicopter rotors under icing conditions by coupling the iced rotor’s aerodynamics, analyzed by CFD, with the rotor’s structural characteristics, analyzed by CSD.

The current work introduces supercomputer-based computational approaches capable of assessing the impact of ice accretion on the aerodynamics, blade dynamics, vibrations and loading of a rotorcraft. The rigid and elastic motions of the blades are accounted for through a loose coupling of the flow solver to a multibody dynamics solver. The coupling framework allows for comprehensive aeroelastic simulations of iced rotors in hover and in forward flight.

The flow and structural modules were validated on a full helicopter configuration in forward flight using the ROBIN experimental model. The tip structural deflections were in very close agreement with the experimental measurements.

The results of the CFD analyses are limited by the available experimental results they can be compared to. In dry air CFD, three-dimensional (3D) experiments occur first and CFD is then compared to them; in icing, the opposite is true: 3D experiments (if they are ever done, as they are very expensive) chase CFD and sometimes never occur.

This paper presents an outline of how CFD and computational stress dynamics (CSD) analyses can be linked and provides a toolbox for deeper investigation of the complex flows over helicopters operating under difficult in-flight icing conditions.

More and more helicopters are designed to be able to operate in hostile environments such as rescuing and saving lives over the oceans or mountains, conditions under which icing encounters cannot be avoided.

A loosely coupled CFD/CSD framework that accounts for the rotor blades structural response to aerodynamic loading and ice accretion in hover and forward flight has been presented. This versatile and cost-effective framework provides a more accurate estimation of the helicopter rotor performance and its degradation due to icing encounters during the early design stages than traditional CFD tools.

This study aims to evaluate blast loads on and the response of submerged structures.

An arbitrary Lagrangian–Eulerian method is developed to model fluid–structure interaction (FSI) problems of close-in underwater explosions (UNDEX). The “fluid” part provides the loads for the structure considers air, water and high explosive materials. The spatial discretization for the fluid domain is performed with a second-order vertex-based finite volume scheme with a tangent of hyperbola interface capturing technique. The temporal discretization is based on explicit Runge–Kutta methods. The structure is described by a large-deformation Lagrangian formulation and discretized via finite elements. First, one-dimensional test cases are given to show that the numerical method is free of mesh movement effects. Thereafter, three-dimensional FSI problems of close-in UNDEX are studied. Finally, the computation of UNDEX near a ship compartment is performed.

The difference in the flow mechanisms between rigid targets and deforming targets is quantified and evaluated.

Cavitation is modeled only approximately and may require further refinement/modeling.

The results demonstrate that the proposed numerical method is accurate, robust and versatile for practical use.

Better design of naval infrastructure [such as bridges, ports, etc.].

To the best of the authors’ knowledge, this study has been conducted for the first time.

The purpose of this paper is to determine the reason for the discrepancy in estimated and observed damage caused by fragmenting charges in closed environments.

A series of carefully conducted physical and numerical experiments was conducted. The results were analyzed and compared.

The analysis shows that for fragmenting charges in closed environments, dust plays a far larger role than previously thought, leading to much lower pressures and damage.

In light of these findings, many assumptions and results for fragmenting charges in closed environments need to be reconsidered.

This implies that for a far larger class of problems than previously estimated it is imperative to take into consideration dust production and its effect on the resulting pressures.

This is the first time such a finding has been reported in this context.

The purpose of this paper is to evaluate the prediction capability of comprehensive structural dynamics (CSD) analysis codes for the higher harmonic control aeroacoustic rotor test (HART) II data.

A nonlinear flexible multibody dynamics analysis code DYMORE, as well as the comprehensive analytical model of rotorcraft aerodynamics and dynamics (CAMRAD) II, are used to perform the task. The predicted results on rotating free vibration analysis, airloads, blade elastic motions, and structural moments are correlated with the measured data for the baseline, minimum noise, and minimum vibration cases.

The DYMORE analysis results with a free wake model show a good performance in capturing blade vortex interaction peaks in the prediction of section normal forces but apparently with a phase shift problem. The high‐frequency behavior in the airloads signal does not affect much on the aeroelastic response and structural moments of the rotor.

The present approach uses two separate CSD codes to systematically validate the HART II data. The accuracy of each code on structural dynamic aspects of HART II rotor is assessed using a consistent set of inputs. The effects of blade tip deflections on the interaction of blades and their trailed vortices leading to a reduced noise emission are also investigated.

Responsible for lift generation, the helicopter rotor is an essential component to protect against ice accretion. As rotorcraft present a smaller wing cross-section and a lower available onboard power compared to aircraft, electro-thermal heating pads are favored as they conform to the blades’ slender profile and limited volume. Their optimization is carried out here taking into account, for the first time, the highly three-dimensional (3D) nature of the flow and ice accretion, in contrast to the current state-of-the-art that is limited to two-dimensional (2D) airfoils.

Conjugate heat transfer simulation results are provided by the truly 3D finite element Navier–Stokes analysis package-ICE code, embedded in a proprietary rotorcraft simulation toolkit, with reduced-order modeling providing a time-efficient evaluation of the objective and constraint functions at every iteration. The proposed methodology optimizes heating pads extent and power usage and is versatile enough to address in a computationally efficient manner a wide variety of optimization formulations.

Low-error reduced-order modeling strategies are introduced to make the tackling of complex 3D geometries feasible in todays’ computers, with the developed framework applied to four problem formulations, demonstrating marked reductions to power consumption along with improved aerodynamics.

The present paper proposes a 3D framework for the optimization of electro-thermal rotorcraft ice protection systems, in hover and forward flight. The current state-of-the-art is limited to 2D airfoils.

Limitations in space and city planning constraints have led to the search for alternative shock mitigation devices that are architecturally appealing. The purpose of this paper is to consider a compromise solution which consists of partially open, thick, bending-resistant shapes made of acrylic material that may be Kevlar- or steel-reinforced. Seven different configurations were analyzed numerically.

For the flow solver, the FEM-FCT scheme as implemented in FEFLO is used. The flowfields are initialized from the output of highly detailed 1-D (spherically symmetric) runs. Peak pressure and impulse are stored and compared. In total, seven different configurations were analyzed numerically.

It is found that for some of these, the maximum pressure is comparable to usual, closed walls, and the maximum impulse approximately 50 percent higher. This would indicate that such designs offer a blast mitigation device eminently suitable for built-up city environments.

Future work will consider fully coupled fluid-structure runs for the more appealing designs, in order to assess whether such devices can be manufactured from commonly available materials such as acrylics or other poly-carbonates.

This would indicate that such designs offer a blast mitigation device eminently suitable for built-up city environments.

This is the first time such a semi-open blastwall approach has been tried and analyzed.

The purpose of this paper is to investigate the numerical fluid-structure interaction (FSI) framework for the simulations of mechanical behavior of new vortex generators (VGs) in smooth wavy fin-and-elliptical tube (SWFET) heat exchanger using the ANSYS MFX Multi-field® solver.

A three-dimensional FSI approach is proposed in this paper to provide better understanding of the performance of the VG structures in SWFET heat exchangers associated with the alloy material properties and geometric factors. The Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model are applied for modeling of the turbulent flow in SWFET heat exchanger and the linear elastic Cauchy-Navier model is solved for the structural von Mises stress and elastic strain analysis in the VGs region.

Parametric studies conducted in the course of this research successfully identified illustrate that the maximum magnitude of von Mises stress and elastic strain occurs at the root of the VGs and depends on geometrical parameters and material types. These results reveal that the titanium alloy VGs shows a slightly higher strength and lower elastic strain compared to the aluminum alloy VGs.

This paper is one of the first in the literature that provides original information mechanical behavior of a SWFET heat exchanger model with new VGs in the field of FSI coupling technique.

The purpose of this paper is to investigate the mechanism of sheets ply separation induced by air flow through numerical simulation with two-way FSI (fluid-structure interaction) simulation using ANSYS and theoretical speculation.

The paper primarily establishes a simplified physical model of the sheets ply separation induced by air flow. Then, the force of the air flow acting on the sheet has been analyzed based on the model, and the main factor leading to separation was obtained. Furthermore, the parameter analysis was investigated based on linear stability analysis, from which the factors that affect stable separation are obtained. Finally, a series of numerical simulations are performed to verify the conclusions.

This study shows that the main separation factor is the variable air pressure in the gap between the sheets caused by the dynamic pressure air flow. Increasing the inlet velocity of the flow field will increase the separation distance but excessive velocity will lead to instability. The viscous resistance acting on the sheet and the bending stiffness of the sheet are factors that stabilize the system, and the sheet density and the restoring force can lead to instability.

The paper is one of the first in the literature that investigates the problem of sheets ply separation induced by air flow, which is the primary method for multi-layer separation in sheets de-stacking operations, especially for the high-speed occasion.