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AIAA Science and Technology (SciTech) Forum and Exposition

作者： Piotrowski, Michael G. H. Zingg, David W. Univ Toronto Inst Aerosp Studies Toronto ON M3H 5T6 Canada NASA Ames Res Ctr Moffett Field CA 94035 USA

ISBN: (数字)9781624105784

ISBN: (纸本)9781624105784

A fully-coupled, implicit Newton-Krylov algorithm with laminar-turbulent boundary-layer transition prediction capabilities for three-dimensional external aerodynamic flows has been developed. The gamma-(R) over tildee(theta t) Local Correlation-Based Transition Model with helicity-based crossflow correlations is modified and fully coupled to the Spalart-Allmaras turbulence model in a parallel Newton-Krylov-Schur flow solver. Deep convergence is obtained using an efficient pseudo-transient continuation time marching strategy, consisting of an approximate-Newton phase followed by an inexact-Newton phase, with source-term time stepping and exponential penalty functions used to address the strong sources and non-smooth functions introduced by the transition model. A modification to the Flength function is introduced to improve the numerical convergence behaviour of the model. The current implementation is validated using two- and three-dimensional transition test cases, with the results obtained using the modified transition model comparing well with experiment. The elimination of discontinuities in the transition model makes it a suitable candidate for gradient-based shape optimization algorithms.

关键词： solution algorithm Natural Laminar Flow Spalart Allmaras Turbulence Model Laminar Turbulent Transition Optimization algorithm Angle of Attack Reynolds Averaged Navier Stokes Aerodynamic Shape Optimization Swept Wing Free Stream Turbulence

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Dynamic States Specific Analysis for Belt Conveyor Based on FDM

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International Conference on Mechatronics and Control Engineering (ICMCE 2012)

作者： Shen, Xiao Wang, Qun Fu, Zhouyu Bai, Shuowei Sun, Zhaoyang Shandong Univ Sci & Technol Coll Mech & Elect Engn Qingdao 266590 Peoples R China Datong Coal Min Grp Yangzhou 272100 Jiangsu Peoples R China Shandong Univ Coll Mech eNGN Jinan 250061 Peoples R China

ISBN: (纸本)9783037855959

There are two common research methods on the dynamic states model of belt conveyor in China at present. The mathematical model is built by finite element method then it is solved by numerical method. And the continuous model is built when the belt is treated as elastic body then it is solved by mathematical method. This paper puts forward the establishment of continuous model, the model is solved by FDM and the simulation results are given.

关键词： Belt conveyor Dynamic states specific FDM solution algorithm

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An Exact Method for Solving Selective Maintenance Problems Considering Imperfect Maintenance 8

An Exact Method for Solving Selective Maintenance Problems C...

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8th International Conference on Intelligent Networking and Collaborative Systems (INCoS)

作者： Cao, Wenbin Song, Wenyuan Hu, Qiwei Du, Yinxia Mech Engn Coll Dept Engn Management Shijiazhuang Peoples R China Heibei Polytech Inst Shijiazhuang Peoples R China

ISBN: (纸本)9781509041237

In the past few decades, analytical models for maintenance optimization have been extensively investigated. As research continues, the cases considered during the mathematical modeling are much more practical, as well as complex, which brings many difficulties for solution. In this paper, we present an exact method for solving the selective maintenance model considering multiple maintenance actions. The solution procedure is discussed in detail. Moreover, an example is adopted to verify its efficiency. Compared with total enumeration method, the proposed method can significantly reduce the solution space (about 42.46%). What's more, unlike some intelligent algorithm, this method can always give out an optimal solution. Finally, the effects of available resources on solution space are discussed.

关键词： selective miantnance solution algorithm exact method imperfect maintenance

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Multi-Agent Passive Safe Optimal Control using Integration Constants as State Variables

Multi-Agent Passive Safe Optimal Control using Integration C...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech Forum)

作者： Guffanti, Tommaso D'Amico, Simone Stanford Univ Aeronaut & Astronaut 496 Lomita Mall Stanford CA 94305 USA

ISBN: (数字)9781624106095

ISBN: (纸本)9781624106095

This paper presents a new algorithm that provides optimal control profiles that drive a multi-agent system to a desired state at a desired time, with the guarantee of no collision, for a specified time horizon, even in case of control input application failure. The algorithm is applicable to multi-agent systems governed by nonlinear control-affine dynamics. First, the paper defines the problem of passive safe optimal control, which adds an important layer of safety to the traditional collision avoidance between agents. A multi-agent system is defined passive safe if the agents maintain safe separation even in the case any agent loses control at any time on the trajectory towards the final condition. Second, the paper shows that using the integration constants of an integrable portion of the multi-agent system dynamics as state variables is the key for including efficiently passive safety into an algorithmic framework. In particular, the number of constraints to be enforced reduces from cubic to quadratic in the number of time samples. Finally, using the integration constants, a solution algorithm based on convex programming is formalized and tested on the challenging problem of passive safe optimal control of multi-spacecraft systems in closed orbits of arbitrary eccentricity.

关键词： Trajectory Optimization Multi Agent System solution algorithm Nonlinear Control Spacecraft System Highly Eccentric Orbit Orbital Period Model Predictive Control Saturn Numerical Integration

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Coupled Discrete Adjoints for Multiphysics in SU2

Coupled Discrete Adjoints for Multiphysics in SU2

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AIAA Aviation Forum

作者： Burghardt, Ole Gaugert, Nicolas R. Gomez, Pedro Palacios, Rafael Kattmann, Tobias Economon, Thomas D. TU Kaiserslautern Chair Sci Comp D-67663 Kaiserslautern Germany Imperial Coll London Dept Aeronaut London SW7 2AZ England Bosch Corp Res Fluid Dynam D-71272 Renningen Germany SU2 Fdn San Francisco CA 94158 USA

ISBN: (数字)9781624105982

ISBN: (纸本)9781624105982

Many optimization problems in fluid dynamics are naturally constituted in a larger multiphysics setting, the most prominent ones nowadays being fluid-structure interaction and conjugate heat transfer or combinations of them. In the context of partitioned solution approaches, and from a software perspective, this means that two or more solvers are coupled by exchanging data at common physical boundaries during the simulation. Optimization methods relying on discrete adjoint solutions have to consider such couplings in order to give accurate gradients. This article presents a methodology for how coupled multiphysics adjoints can be computed efficiently in a way that is also independent of the choice or configuration of the underlying physical problem. Based on an implementation in SU2 (an open-source multiphysics simulation and design software(1)) we demonstrate how the same algorithm can be applied for shape sensitivity analysis on a conjugate heat transfer as well as a fluid-structure interaction test case.

关键词： Fluid Structure Interaction Conjugate Heat Transfer Pressure Coefficient Sensitivity Analysis Poisson's Ratio solution algorithm Aerodynamic Shape Optimization Incompressible Flow Material Properties Stiffness Matrices

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Acoustic analysis of a rotor in forward flight with deformable blades through a boundary integral formulation

Acoustic analysis of a rotor in forward flight with deformab...

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AIAA Aviation Forum

作者： Gennaretti, M. de Rubeis, B. Poggi, C. Bernardini, G. Roma Tre Univ Dept Engn I-00146 Rome Italy

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

This paper presents the results of the development of a novel boundary integral formulations suitable for the aerodynamic and aeroacoustic analysis of deformable bodies in arbitrary motion. The starting point is the most general form of the wave equation governing the propagation of perturbations in a fluid medium of aerodynamic and aeroacoustic interest. Therefore, the derived formulation represents the most general integral form solution allowing for the study of aerodynamics and aeroacoustics of rigid or deformable bodies, able to handle both solid and porous boundary surfaces. Two versions of the boundary integral formulation are developed, which differ in terms of the frame of reference in which they are expressed. First, the validation of the corresponding implemented numerical solution algorithms is obtained by confirming through cross-comparison between the predictions their theoretical equivalence. Then, the noise radiated by the blades of an advancing rotor subject to aeroelastic bending and torsion is examined, with particular attention on the aeroacoustic effect of blade deformations. The correlations with the available experimental measurements show an overall good quality of the obtained numerical predictions.

关键词： Ffowcs Williams Hawkings Equation Rotor Aerodynamics solution algorithm Green's Function Aeroelastic Analysis Flexible Structures Acoustic Emission Structural Dynamics Rotor Blades Aviation

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Evaluation Model of Leadership Competency Based on Fuzzy Information and Its algorithm Implementation 2

Evaluation Model of Leadership Competency Based on Fuzzy Inf...

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2nd International Conference on Big Data Economy and Information Management, BDEIM 2021

作者： Cui, Yan Qi, Jun Mao, Hongtao Hu, Nan Liu, Jingfeng Li, Zhenyu Zhang, Yushi Liu, Yubo State Grid Liaoning Electric Power Supply Company Limited Shenvang China

ISBN: (纸本)9781665482882

Competency model is widely used in enterprises, and effective evaluation of leadership competency is the basis and prerequisite for their selection, training, performance management and personal development. Based on a systematic review of relevant literatures, this study proposed a leadership competency evaluation model based on fuzzy information, and designed a solution algorithm. Taking the leadership competency evaluation of A company as a case, this study carried out the identification of individual advantage characteristics of leadership competency, and performed its individual agent evaluation and democratic agent evaluation. The results show that the algorithm can effectively identify the advantage characteristics of leaders. It also helps to explore the inherent strength structure of leadership competency and provides technical methods for individual growth and improvement. © 2021 IEEE.

关键词： component evaluation model fuzzy information leadership competency solution algorithm

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A Review of Models and Methods for Precise Load Control Strategies

A Review of Models and Methods for Precise Load Control Stra...

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2024 Boao New Power System International Forum - Power System and New Energy Technology Innovation Forum, NPSIF 2024

作者： Wei, Aoqiu Wang, Shengli Xie, Li Luo, Cheng Xu, Lihui Maimaitituxun, Alimire Zheng, Hua School of Electrical and Electronic Engineering North China Electric Power University Beijing China Kashgar Power Supply Company State Grid Xinjiang Electric Power Co. Ltd. Kashgar China

ISBN: (纸本)9798331504557

With the advancement of China's "dual carbon"goals, renewable energy represented by wind and solar power is set to become the main source of the future power system. However, the uncertainty of renewable energy output significantly affects the supply-demand balance of the system. In this context, This paper provides a review of precise load control technologies based on the actual scheduling needs of the power grid. It categorizes controllable loads into traditional controllable loads and new controllable loads, explaining the application scenarios of load control in peak shaving, frequency regulation, and emergency load shedding. It also analyzes the models of various controllable loads and presents solution methods based on physical models as well as data-driven models. Finally, it looks ahead to the future development of precise load control technology. © 2024 IEEE.

关键词： control model load classification objective function solution algorithm

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EFFECTIVE TREATMENT OF THE SINGULAR LINE BOUNDARY-PROBLEM FOR 3-DIMENSIONAL GRIDS

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AIAA JOURNAL 1993年第10期31卷 1757-1758页

作者： PALMER, G VENKATAPATHY, E ELORET INST MT VIEWCA 94043

THREE-DIMENSIONAL grids of rotation contain a singular line where the radial grid planes meet. When the flow equations are transformed into generalized coordinates, a mathematical singularity is introduced into the governing equations. Specifically, the grid Jacobian J becomes infinite along the singular line. This can introduce nonphysical perturbations in the flow solution, particularly if a finite-difference solution algorithm is used. A number of recent publications1-5 have discussed problems associated with the singular line. This paper presents a method for eliminating the axis singularity. The governing equations are reformulated using a redefined grid Jacobian that can be evaluated at the singular line. This allows a finite-difference algorithm to compute a smooth, continuous solution in the region of the singular line.

关键词： solution algorithm Flow Equations Angle of Attack Blunt Bodies Navier Stokes Equations Stagnation Point Radial Velocity Aerospace Sciences Inviscid Flow Perfect Gas

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Newton-Krylov Solver for Robust Turbomachinery Aerodynamic Analysis

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AIAA JOURNAL 2020年第3期58卷 1320-1336页

作者： Xu, Shenren Mohanamuraly, Pavanakumar Wang, Dingxi Mueller, Jens-Dominik Northwestern Polytech Univ Yangtze River Delta Res Inst Taicang 215400 Peoples R China Queen Mary Univ London Sch Engn & Mat Sci London E1 4NS England Shaanxi Key Lab Internal Aerodynam Aeroengines Sch Power & Energy 1 Dongxiang Rd Xian 710072 Peoples R China Shaanxi Key Lab Internal Aerodynam Aeroengines 1 Dongxiang Rd Xian 710072 Peoples R China

Steady computational fluid dynamics solvers based on the Reynolds-averaged Navier-Stokes equations are the primary workhorses for turbomachinery aerodynamic analysis due to their good engineering accuracy at a low computational cost. However, even state-of-the-art steady solvers suffer from convergence slowdown or failure when applied to challenging off-design conditions. This severely limits the reliable nonlinear and linearized turbomachinery aerodynamic analysis over a wide operating range. To alleviate the convergence difficulties, a nonlinear flow solver using the Newton-Krylov method is developed. This is the first time the Newton-Krylov algorithm is used for achieving robust analysis of turbomachinery aerodynamics in the open literature. The proposed solution algorithm features 1) the exact Jacobian matrix forming, 2) straightforward parallelization, and 3) a reliable globalization strategy;and it aims to achieve fast machine-zero convergence. The solver accuracy is validated using four test cases: an airfoil, a linear turbine cascade, a centrifugal compressor, and an axial compressor. Machine-zero convergence is achieved for all cases over a wide range of operating conditions without manual intervention. The method shows great potential for enabling an automated and reliable whole-map turbomachinery aerodynamic analysis, and it paves the way for a robust and efficient linearized aerodynamic analysis, such as adjoint, time-linearized, and eigenvalue analyses.

关键词： Turbomachinery Reynolds Averaged Navier Stokes Courant Friedrichs Lewy Airfoil Centrifugal Compressor Aerodynamics solution algorithm Message Passing Interface Flow Conditions Conductivity Coefficients

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