Patrick Hu

Material Point Method Applied to Fluid-Structure Interaction (FSI)/Aeroelasticity Problems

The material point method (MPM) combined with adaptive mesh refinement (AMR) technique is applied to investigate complicated fluid-structure interactions (FSI) such as aircraft wing flutter and other aeroelastic problems. The advantage of MPM over traditional fluid-structure interaction (FSI) methods is its computational efficiency, accuracy and robustness. MPM avoids explicit discretization of convection terms in momentum equations and the fluid-structure interaction is realized by coupling the fluid and solid stress at the interface. The states of material points are updated through the solution on background Cartesian grid node which is fixed during the calculation, thus no mesh distortion problem needs to be dealing with in the case of large deformation. The dynamic AMR can effectively decrease the total number of background mesh nodes and material points for complicated FSI problems. Preliminary results indicate that MPM with dynamic AMR can be a powerful tool to simulate FSI/aeroelastic problems for aerial vehicles. A 3D MPM code (a part of ASTE-P toolset) has been developed at Advanced Dynamics Inc. (ADI) with the ability to model complex fluid-structure interaction (FSI) problems.

Modeling and Simulation of a Jet Impingement on Aircraft Structure

The unsteady aerodynamic loading and noise generated by the high-speed jet exiting from aircraft engine is of paramount importance in the design and analysis of aircraft, particularly for the STOVL aircraft. A numerical study based on Large Eddy Simulation (LES) of a supersonic jet impinging on a flat plate and reflected on a “lift” plate which mimics the aircraft structure is presented in this paper. A high-fidelity LES solver was employed for this study to accurately capture the shock-turbulence interaction occurring in this flow. Experiments conducted for a supersonic jet at a Mach number of 1.5 and Reynolds number of 7x10 5 was considered for code validation. Preliminary results are in qualitatively good agreement with the experimental results. Results related to quantitative comparison with experimental measurement will be presented in a later paper. The pressure loading on the aircraft structure and the aeroacoustics computed using LES results can be used for structural analysis of the aircraft to be studied.

ASTE-P: Software Package for Multidisciplinary, Multiphysics, Multiscale and Multifidelity Analysis and Design (4MAO) of Aerospace Vehicles

Advanced Dynamics has developed an Integrated Variable-Fidelity Tool Set – ASTE-P for Modeling and Simulation of Aero-Servo-Thermo-Elasticity and Propulsion (ASTE-P) of Aerospace Vehicles Ranging from Subsonic to Hypersonic Flights. The ASTE-P software tool set is developed in the state-of-the-art and commercial standard and enables accurate integration and tight/loose coupling of the fluid, structural and control field simulation with variable fidelity options available. The ASTE-P software tool can be applicable to modeling and simulation of aerodynamics, structural dynamics, flight control and propulsion dynamics as well as more important interactions of these dynamics. All flight regimes from subsonic to hypersonic are covered. The interface of structural/control surface motion and vibration modes with fluid flows is modeled using either unified particle-based methods (MPM/PPM) or FVM/FEM based tight/loose coupled fluid/structure solving algorithms. The Euler and RANS based solvers enable the accurate prediction of nonlinear coupled fluid-structure problems in aeroelasticity and the embedded fluid and structural dynamics solvers make the software self-contained and not require the integration of two separate third-party fluid and structure solvers for aeroelastic modeling and simulation. Three levels of simulation environments are included in ASTE-P tool set: (1) the bottom level of high-fidelity and full-order simulation environment, (2) middle level of fast analysis and evaluation environment which is based upon reduced order models (ROM) and provides fast turn-around time, and (3) top level of rapid design and optimization environment. The test cases presented in this paper indicate that the functionalities of ASTE-P are compatible or even more efficient than the similar software that is currently available.

Modeling and Simulation of Multi-fidelity AE/ASE Dynamics with the Integrated and Variable-Fidelity Toolset - "ASTE-P"

Advanced Dynamics Inc. has developed an Integrated Variable-fidelity Toolset, “ASTEP”, for Modeling and Simulation of Aeroservothermoelasticity-Propulsion (ASTE-P) Effects of Aerospace Vehicles Ranging from Subsonic to Hypersonic Flight. “ASTE-P” was developed in the state-of-the-art and commercial standard and enables accurate integration and tight/loose coupling of the fluid, structural and control field simulation with variable fidelity options available. The ASE module of ASTE-P toolset has a comprehensive capability for modeling and simulation of multi-fidelity Aeroservoeastic (ASE) Dynamics of aerospace vehicles. The Multi-fidelity AE/ASE dynamics modeling and simulation environments in ASTE-P toolset include: (1) the high-fidelity and full-order AE/ASE dynamics modeling and simulation environment, (2) fast AE/ASE dynamics modeling and simulation environment that is based upon reduced order models (i.e., POD-ROM, VolterraROM, etc.). In ASTE-P, the CFD reduced order model (ROM) is coupled with flight dynamics and structural dynamics models to build the mathematical system model, which is in-turn imported into Matlab/Simulink to conduct various dynamic analyses, including stability, flutter/LCO, maneuver, ejection and gust. In this paper, several cases of AE/ASE dynamics modeling will be presented to illustrate the numerical procedure for multi-fidelity AE/ASE dynamics modeling and simulation, and the computational capability of ASTE-P for AE/ASE dynamics modeling and simulation will be demonstrated. Finally, the computational efficiency with the optional variable-fidelity will be discussed.

Integrated and Multi-fidelity Software Package for Aero- Servo-Thermo-Elasticity and Propulsion (ASTE-P) of Aero- space Vehicles from Subsonic to Hypersonic Flight

Advanced Dynamics has developed an Integrated Variable-Fidelity Tool Set - ASTE-P for Modeling and Simulation of Aero-Servo-Thermo-Elasticity and Propulsion (ASTE-P) of Aerospace Vehicles Ranging from Subsonic to Hypersonic Flights. The ASTE-P software tool set is developed in the state-of-the-art and commercial standard and enables accurate integration and tight/loose coupling of the fluid, structural and control field simulation with variable fidelity options available. The ASTE-P software tool can be applicable to modeling and simulation of aerodynamics, structural dynamics, flight control and propulsion dynamics as well as more important interactions of these dynamics. All flight regimes from subsonic to hypersonic are covered. The interface of structural/control surface motion and vibration modes with fluid flows is modeled using either unified particle-based methods (MPM/PPM) or FVM/FEM based tight/loose coupled fluid/structure solving algorithms. The Euler/RANS/LES/DES solvers enable the accurate prediction of nonlinear coupled fluidstructure problems in aeroelasticity and the embedded fluid and structural dynamics solvers make the software self-contained and not require the integration of two separate third-party fluid and structure solvers for aeroelastic modeling and simulation. Three levels of simulation environments are included in ASTE-P tool set: (1) the bottom level of high-fidelity and full-order simulation environment, (2) middle level of fast analysis and evaluation environment which is based upon reduced order models (ROM) and provides fast turn around time, and (3) top level of rapid design and optimization environment. In several our previous AIAA papers we have reported the integrated framework of ASTE-P and some validation cases, and in this paper we will update the status and enhancement of the ASTE-P recently, and present some new cases we have run to demonstrate that the functionalities of ASTE-P are compatible or even more efficient than the similar software that is currently available.

Rapid Solution and Variable-fidelity Modeling of Aeroelasticity(AE) /Aeroservoelasticity (ASE) Using ASTE-P Toolset

Advanced Dynamics Inc. (ADI) has developed an integrated variable-fidelity toolset, “ASTE-P”, for modeling and simulation of aeroservothermoelasticity-propulsion (ASTE-P) effects of aerospace vehicles ranging from subsonic to hypersonic flights, which enables the accurate integration and tight/loose coupling of the fluid, structural and control field simulation with variable fidelity options available. The AE and ASE modules of ASTE-P toolset have comprehensive capability for modeling and simulation of multi-fidelity Aeroelastic (AE) / Aeroservoeastic (ASE) Dynamics of aerospace vehicles. The multi-fidelity AE/ASE dynamic modeling and simulation environments in ASTE-P toolset include: (1) the high-fidelity and full-order AE/ASE dynamics modeling and simulation environment, (2) fast AE/ASE dynamics modeling and simulation environment that is based upon reduced order models (i.e., POD/ROM, Volterra-ROM, etc.). Recently, the AE and ASE modules of ASTE-P have been succesfully integrated with Matlab/Simulink to enable various AE/ASE dynamic analyses and control system designs, including prediction of flutter/LCO and its suppression. In several of our previous papers, we have reported the rapid modeling and simulation environment in ASTE-P, including ROM models of POD, Volterra series, HDHB, and MSM-MPM aproaches, etc. In this paper, we will present the detailed theory and numerical procedure for coupling LES approach with structural dynamics model for AE modeling of an aerospace vehicle and its components/subcomponents. The improvement of the accuracy for LES over Euler/RANS is clearly demonstrated in present study by using benchmark AGARD 445.6 wing and Mavric wing test cases. I. Introduction eroelastic(AE)/Aeroservoelastic(ASE) dynamics of an aircraft involves aerodynamics and structure dynamics, therefore is a comprehensive and multidisciplinary research area. The analysis and evaluation of the aeroelastic /aeroservoelastic dynamics for aircraft is very important for performance, control and stability analysis of aircraft. Many of the methods that have been developed over the years for simpler AE/ASE models that use, for example, doublet lattice aerodynamics can be adopted for this purpose. However, these models are based on potential flow theory and cannot capture the nonlinear system dynamics in transonic flight regime. High-fidelity model do exist, but if high-fidelity computational fluid dynamics (CFD) and computational structure dynamics (CSD) approaches are used, the large degree-of-freedom, nonlinear fluid and structural system may take days to weeks to finish the computation and, thus are cost prohibitive. Advanced Dynamics Inc. (ADI) has developed an integrated multi-fidelity toolset, “ASTE-P” [1-3], for modeling and simulation of AE/ASE dynamics of aerospace vehicles ranging from subsonic to hypersonic flights, which enables the accurate integration and tight/loose coupling of the fluid, structural and control

Computational Aeroacoustics of Turbulent Jets Using Large Eddy Simulation and Acoustic Intensity Based Method of the ASTE-P Toolset

Suppressing noise generated by airplanes continues to gather more and more interest towards future development of aviation. First step in doing so is accurately predicting jet noise. Turbulence models play a key role in accurately predicting such noise. A non-eddyviscosity-based large-eddy simulation subgrid-scale model, namely the approximate deconvolution model, will be used with high-order numerics and accurate boundary conditions to predict supersonic noise generated by free jets. A hybrid approach for jet noise prediction wherein the near-field sources are computed using LES and the far-field sound results are predicted using an efficient method called Acoustic Intensity Based Method (AIBM) is also considered. Results obtained using AIBM are compared with LES results for validation.

Reduced Order Model Based Simulation of Aeroelastic(AE) Aeroservoelastic (ASE) Dynamics Using ASTE-P Toolset

Advanced Dynamics Inc. (ADI) has developed an integrated variable-fidelity toolset, “ASTE-P”, for modeling and simulation of aeroservothermoelasticity-propulsion (ASTE-P) effects of aerospace vehicles ranging from subsonic to hypersonic flights, which enables the accurate integration and tight/loose coupling of the fluid, structural and control field simulation with variable fidelity options available. The ASE module of ASTE-P toolset has comprehensive capability for modeling and simulation of multi-fidelity Aeroelastic (AE) / Aeroservoeastic (ASE) Dynamics of aerospace vehicles. The multi-fidelity ASE dynamic modeling and simulation environments in ASTE-P toolset include: (1) the high-fidelity and full-order AE/ASE dynamics modeling and simulation environment, (2) fast ASE dynamics modeling and simulation environment that is based upon reduced order models (i.e., POD-ROM, Volterra-ROM, etc.). Recently, the ASE module of ASTE-P has been successfully integrated with Matlab/Simulink to enable various AE/ASE dynamic analyses and control system design, including prediction of flutter/LCO and suppression. In this paper, we will present the detailed theory and numerical procedure for (1) how to construct the ROM models in ASTE-P and (2) how to perform various AE/ASE modeling and simulation in ASTE-P running environment with Matlab scripts. Two examples will be presented to illustrate the numerical procedure and demonstrate the capability of the user-friendly platform built upon the integrated ASTE-P and Matlab/Simulink environment.

Numerical Simulations of Supersonic Jet Impinging on a Flat Plate

A high-order accurate, robust, and efficient Large Eddy Simulation (LES) technique is employed to study the complex flow and acoustics of high-speed jet impingement. This solver is developed using innovative stateof-the-art numerics to improve stability and efficiency without sacrificing accuracy. The solver is based on multiblock, body-fitted grid and can be extended to complex geometries. The solver features an innovative subgrid-scale (SGS) model which is similar in accuracy to popular SGS models but at a fraction of the computational expenses. Recently proposed accurate, minimum dissipation shock-capturing scheme is also incorporated into the solver. Another innovative feature of the solver is the generalized curvilinear characteristic based non-reflecting boundary conditions suitable for computational aeroacoustics in complex geometries. A high-speed jet at a Mach number of 1.5 and Reynolds number of 7x10 was simulated using this solver. Results are qualitatively in good agreement with experimental measurements. A multiple jet test case featuring four jets with square cross-section is also studied using this solver.