Reengineering of the aircraft structural life prediction process to fully exploit advances in very high performance digital computing is proposed. The proposed process utilizes an ultrahigh fidelity model of individual aircraft by tail number, a Digital Twin, to integrate computation of structural deflections and temperatures in response to flight conditions, with resulting local damage and material state evolution. A conceptual model of how the Digital Twin can be used for predicting the life of aircraft structure and assuring its structural integrity is presented. The technical challenges to developing and deploying a Digital Twin are discussed in detail.

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Reengineering Aircraft Structural Life Prediction Using a Digital Twin

Full-scale unsteady RANS CFD simulations of ship behaviour and performance in head seas due to slow steaming

Ship motions using single-phase level set with dynamic overset grids

Grid generation for overset grids on complex geometry can be divided into four main steps: geometry processing, surface grid generation, volume grid generation and domain connectivity. For each of these steps, the procedures currently practiced by experienced users are described. Typical problems encountered are also highlighted and discussed. Most of the guidelines are derived from experience on a variety of problems including space launch and return vehicles, subsonic transports with propulsion and high lift devices, supersonic vehicles, rotorcraft vehicles, and turbomachinery.

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Best Practices in Overset Grid Generation

SUGGAR: A General Capability for Moving Body Overset Grid Assembly

In this paper we investigate phenomena associated with particle impingement on dynamic airfoils. Using an Eulerian based solver, a droplet velocity field is computed throughout the computational domain. This solver is used to scrutinize particular concepts, with the intent to save computation time, listed as follows: (i) The applicability of different time-averaging techniques to calculate an average local collection efficiency for dynamic simulations. (ii) Comparison between static and dynamic bodies undergoing particle surface interactions. (iii) The use of a numerically viscous solution to the Euler equations instead of a fully viscous solution to predict proper particle trajectories on dynamic airfoils. Guidance is provided herein, for the applicability of solution methods to reduce computational costs.

A numerical investigation of droplet/particle impingement on a dynamic airfoil

A CFD Approach for Predicting 3D Ice Accretion on Aircraft

The simulation of physical processes using numerical models typically requires the execution of a number of tools. A significant amount of user time is required to simply manage this simulation process. This paper describes an integrated simulation environment infrastructure that has been developed to assist the user in managing the simulation process. The environment can provide graphical user interfaces (GUI) to non-GUI tools, manage the flow of data and execution among the tools, and reduce the learning curve for the tools by removing mundane details that are managed by the environment. A sample simulation environment has been developed and is presented for overset computational fluid dynamics simulations.

An integrated simulation environment for cfd and other computational disciplines

This paper describes the addition of an overset grid capability to the DPLR flow solver for hypersonic flow in thermochemical nonequilibrium. Modifications to the preexisting flow solver were simplified through the use of DiRTlib, a “solver neutral” library of overset utilities. The new capability is demonstrated on a series of examples, including the Orion Crew Module and other reentry vehicles. For the overset grids used in these examples, the hole cutting and interpolation stencils were determined using SUGGAR, a generalized grid assembly code that can naturally accommodate both the three-dimensional and true two-dimensional cell-centered discretization schemes in DPLR. First a series of building-block examples are presented which highlight aspects of the new capability and assess the technique with comparisons to baseline, block-structured discretizations. The new capability is then exercised for the specific case of a tension tie geometry protruding from the Orion heatshield at both wind tunnel and flight conditions. The addition of overset capability to the DPLR flow solver is seen to be an essential feature for analyzing increasingly complex geometries in thermochemical nonequilibrium.

Overset Grid Applications in Hypersonic Flow Using the DPLR Flow Solver

A computational fluid dynamics (CFD) method is adapted, validated and applied to spinning gear systems with emphasis on predicting windage losses. Several spur gears and a disc are studied. The CFD simulations return good agreement with measured windage power loss. Turbulence modeling choices, the relative importance of viscous and pressure torques with gear speed and the physics of the complex 3-D unsteady flow field in the vicinity of the gear teeth are studied.

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Ralph W. Noack

Papers

A numerical investigation of droplet/particle impingement on a dynamic airfoil

A CFD Approach for Predicting 3D Ice Accretion on Aircraft

An integrated simulation environment for cfd and other computational disciplines

Overset Grid Applications in Hypersonic Flow Using the DPLR Flow Solver

CFD Technology for Rotorcraft Gearbox Windage Aerodynamics Simulation