추진기관 노즐의 2차원 열-유동-다물체 동역학 연동 해석

은원종,김재원,곽준영,신상준,권오준,Oliver A. Bauchau 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.11

다양한 구성품으로 이루어진 추진기관의 노즐 구조물에서는 고온 고속상태의 복잡한 유동현상과 비선형 거동이 나타난다. 이러한 현상을 정확하게 예측하기 위해서는 유동해석과 다물체 구조해석의 연계해석이 필요하다. 본 논문에서는 노즐의 다양한 구성품들은 다물체 구조물로 모델링하였고, 2 차원 노즐의 내부에서 정상 유동 해석을 통하여 노즐 구성품에 작용하는 열 및 압력하중을 계산하였다. 유동 해석의 압력하중 결과를 유연 다물체 동역학 해석 프로그램인 DYMORE 에 적용하여 정상상태 유체-다물체 동역학 연동 해석을 수행하였다. 이와 같은 일방향 연동해석에서 발생하는 변위는 유한요소 해석 프로그램인 MSC.NASTRAN 해석 결과와 비교하여 검증하였다. In order to predict complex behavior of an engine nozzle, coupling analysis is generally required between fluid and multibody dynamics. In this paper, various components in the nozzle were modeled as flexible multibody components. Then temperature and pressure on the nozzle wall were predicted by the steady-state flow analysis for the two-dimensional nozzle. Steady-state multibody dynamics analysis was then performed by using DYMORE. Deflection induced at the nozzle wall was obtained by the present one-way coupling analysis. Finally the resulting deflections were compared with the static structural analysis results using MSC.NASTRAN.

2 차원 제트 엔진 가변 노즐 형상에 대한 열-유동-유연 다물체 연동 해석

은원종,김재원,신상준,권오준,Olivier A. Bauchau 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.4

다양한 구성품으로 이루어진 추진기관의 노즐 구조물에서는 고온 고속상태의 복잡한 유동현상과 비선형 거동이 발생한다. 이러한 현상을 정확하게 예측하기 위해서는 유동해석과 다물체 구조해석의 연계해석이 필요하다. 본 논문에서는 노즐의 다양한 구성품들은 다물체 구조물로 모델링하였고, 2차원 노즐의 내부에서 정상 유동 해석을 통하여 노즐 구성품에 작용하는 열 및 압력하중을 계산하였다. 유동 해석의 압력하중 결과를 유연 다물체 동역학 해석 프로그램인 DYMORE에 적용하여 정상상태 유동-다물체 동역학 연동 해석을 수행하였다. 특허 형상의 2차원 노즐에 대하여, 단방향 및 양방향 연동해석을 수행하여 기계적 변형률을 계산하고. MSC.NASTRAN의 열해석을 통한 열 변형률 결과를 합산하여 전체 변형률에 대한 결과를 확인하였다. In order to analyze complex behavior of an engine nozzle, coupled analysis will be generally required between fluid and multibody dynamics. In this paper, various components in the nozzle were modeled as flexible multibody components. Then temperature and pressure on the nozzle wall were predicted by the steady-state CFD flow analysis for the two-dimensional nozzle. Nonlinear multibody dynamic analysis was performed by using DYMORE. For the coupled analysis, the two-dimensional patent nozzle configurations were selected. And, then the one-way and both-way coupled analysis was performed. Heat conduction and thermal analysis were also conducted by MSC.NASTRAN. Finally, total strain results were obtained as a summation of the mechanical and thermal strain components.

Coupled Analysis of Thermo-Fluid-Flexible Multi-body Dynamics of a Two-Dimensional Engine Nozzle

Eun, WonJong,Kim, JaeWon,Kwon, Oh-Joon,Chung, Chanhoon,Shin, Sang-Joon,Bauchau, Olivier A. The Korean Society for Aeronautical and Space Scie 2017 International Journal of Aeronautical and Space Sc Vol.18 No.1

Various components of an engine nozzle are modeled as flexible multi-body components that are operated under high temperature and pressure. In this paper, in order to predict complex behavior of an engine nozzle, thermo-fluid-flexible multi-body dynamics coupled analysis framework was developed. Temperature and pressure on the nozzle wall were obtained by the steady-state flow analysis for a two-dimensional nozzle. The pressure and temperature-dependent material properties were delivered to the flexible multi-body dynamics analysis. Then the deflection and strain distribution for a nozzle configuration was obtained. Heat conduction and thermal analyses were done using MSC.NASTRAN. The present framework was validated for a simple nozzle configuration by using a one-way coupled analysis. A two-way coupled analysis was also performed for the simple nozzle with an arbitrary joint clearance, and an asymmetric flow was observed. Finally, the total strain result for a realistic nozzle configuration was obtained using the one-way and two-way coupled analyses.

Domain Decomposition Approach Applied for Two- and Three-dimensional Problems via Direct Solution Methodology

Kwak, Jun Young,Cho, Haeseong,Chun, Tae Young,Shin, SangJoon,Bauchau, Olivier A. The Korean Society for Aeronautical and Space Scie 2015 International Journal of Aeronautical and Space Sc Vol.16 No.2

This paper presents an all-direct domain decomposition approach for large-scale structural analysis. The proposed approach achieves computational robustness and efficiency by enforcing the compatibility of the displacement field across the sub-domain boundaries via local Lagrange multipliers and augmented Lagrangian formulation (ALF). The proposed domain decomposition approach was compared to the existing FETI approach in terms of the computational time and memory usage. The parallel implementation of the proposed algorithm was described in detail. Finally, a preliminary validation was attempted for the proposed approach, and the numerical results of two- and three-dimensional problems were compared to those obtained through a dual-primal FETI approach. The results indicate an improvement in the performance as a result of the implementing the proposed approach.

Development of a Finite Element Domain Decomposition Analysis with Improved Characteristics

JunYoung Kwak(곽준영),TaeYoung Chun(전태영),SangJoon Shin(신상준),Olivier A. Bauchau 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

This paper describes development of an improved computational algorithm based on finite element domain decomposition technique for a large scale structural analysis. We compared computational algorithms corresponding to the original FETI method and the presently improved FETI approach with regard to convergence. In the original FETI method, Lagrange multipliers were introduced to enforce compatibility at the interface DOF’s. The improved FETI algorithm uses local Lagrange multipliers with an augmented Lagrangian formulation (ALF) as penalty formulation of the problem for computational robustness and efficiency. The present mathematical algorithm is relatively simple and leads to improved convergence of numerical computation. Thus, this algorithm will be attractive for FETI domain decomposition method. For validation of the present approach, we compared its numerical results with those obtained by the original FETI method.

Improvement of finite element domain decomposition method using local Lagrange multipliers

Jun Young KWAK,Haeseong CHO,Sang Joon SHIN,Olivier A. BAUCHAU 한국산업응용수학회 2013 한국산업응용수학회 학술대회 논문집 Vol.8 No.1

This paper presents the structural computational algorithm based on the improved finite element domain decomposition method using local Lagrange multipliers. The proposed approach uses local Lagrange multipliers with an augmented Lagrangian formulation to achieve computational robustness and efficiency. A parallel algorithm for the improved version of the proposed FETI-local method is further developed and numerical results are compared with those obtained by the previously developed FETI-local and dual-primal FETI methods to demonstrate the improved efficiency.

Computational Approach for an improved finite element domain decomposition method

JunYoung Kwak,TaeYoung Chun,SangJoon Shin,Olivier A. Bauchau 한국산업응용수학회 2011 한국산업응용수학회 학술대회 논문집 Vol.6 No.2

This paper presents the development of an improved computational algorithm based on finite element domain decomposition technique for a large scale static and dynamic structural analysis. The proposed algorithm is compared with the well-known FETI approach with regards to convergence and efficiency characteristics. The proposed approach uses both local and global Lagrange multipliers together with an augmented Lagrangian formulation to achieve computational robustness and efficiency. We additionally developed the transient time computational algorithm by extending the proposed FETI method. Numerical predictions are compared with those obtained by the original and dual-primal FETI methods to demonstrate the improvements by the proposed approach. The present algorithm is relatively simple and leads to improved convergence and efficiency characteristics.

ADVANCED DOMAIN DECOMPOSITION METHOD BY LOCAL AND MIXED LAGRANGE MULTIPLIERS

JUNYOUNG KWAK,TAEYOUNG CHUN,HAESEONG CHO,SANGJOON SHIN,OLIVIER A. BAUCHAU 한국산업응용수학회 2014 Journal of the Korean Society for Industrial and A Vol.18 No.1

This paper presents development of an improved domain decomposition method for large scale structural problem that aims to provide high computational efficiency. In the previous researches, we developed the domain decomposition algorithm based on augmented Lagrangian formulation and proved numerical efficiency under both serial and parallel computing environment. In this paper, new computational analysis by the proposed domain decomposition method is performed. For this purpose, reduction in computational time achieved by the proposed algorithm is compared with that obtained by the dual-primal FETI method under serial computing condition. It is found that the proposed methods significantly accelerate the computational speed for a linear structural problem.

Domain Decomposition Approach Applied for Two- and Three-dimensional Problems via Direct Solution Methodology

Jun Young Kwak,Haeseong Cho,Tae Young Chun,SangJoon Shin,Olivier A. Bauchau 한국항공우주학회 2015 International Journal of Aeronautical and Space Sc Vol.16 No.2

This paper presents an all-direct domain decomposition approach for large-scale structural analysis. The proposed approach achieves computational robustness and efficiency by enforcing the compatibility of the displacement field across the subdomain boundaries via local Lagrange multipliers and augmented Lagrangian formulation (ALF). The proposed domain decomposition approach was compared to the existing FETI approach in terms of the computational time and memory usage. The parallel implementation of the proposed algorithm was described in detail. Finally, a preliminary validation was attempted for the proposed approach, and the numerical results of two- and three-dimensional problems were compared to those obtained through a dual-primal FETI approach. The results indicate an improvement in the performance as a result of the implementing the proposed approach.

국부 및 혼합 Lagrange 승수법을 이용한 영역분할 기반 유한요소 구조해석 기법 개발

곽준영,조해성,신상준,올리비에 보쇼,Kwak, Jun Young,Cho, Hae Seong,Shin, Sang Joon,Bauchau, Olivier A. 한국전산구조공학회 2012 한국전산구조공학회논문집 Vol.25 No.6

본 논문에서는 대규모 구조해석을 위하여 국부(local) 및 전역-국부 혼합(mixed) Lagrange 승수(Lagrange multiplier)를 이용한 새로운 유한요소 영역분할 기법을 제시한다. 제시되는 FETI 알고리즘은 계산 효율성을 향상시키기 위하여 기존의 FETI 기법들에서 사용되어 온 전통적인 Lagrange 승수법과는 달리, 국부 및 전역-국부 혼합 Lagrange 승수를 도입하고 ALF(Augmented Lagrangian Formulation)과의 결합을 유도하여 공유면 문제(interface problem)의 해의 수렴성을 향상 시켰다. 추가적으로, 몇 가지 수치예제 계산을 통해 기존의 FETI-DP 기법과 비교하여 유연도 행렬의 조건수, 계산 시간 그리고 메모리 사용량에 대한 계산결과를 제시하였다. In this paper, a finite element domain decomposition method using local and mixed Lagrange multipliers for a large scal structural analysis is presented. The proposed algorithms use local and mixed Lagrange multipliers to improve computational efficiency. In the original FETI method, classical Lagrange multiplier technique was used. In the dual-primal FETI method, the interface nodes are used at the corner nodes of each sub-domain. On the other hand, the proposed FETI-local analysis adopts localized Lagrange multipliers and the proposed FETI-mixed analysis uses both global and local Lagrange multipliers. The numerical analysis results by the proposed algorithms are compared with those obtained by dual-primal FETI method.