열압축기 내 다상유동에 대한 정확하고 효율적인 수치해석 연구구

학위논문 (박사)-- 서울대학교 대학원 : 공과대학 기계항공공학부, 2018. 2. 김종암.Most previous numerical researches on flow field inside Thermal Vapor Compressor (TVC) has been conducted neglecting phase changing process around shock-train region. It may provide the plausible results on suction performance of target problem, however, it also can be fallen into erroneous prediction. The present study focuses above limitations and provides computational improvements through multi-phase flow modeling and analysis. In order to capture the multi-phase flow physics accurately and provide reliable results, several numerical methods and models, including the shock-stable multi-phase AUSMPW+ N scheme, phase changing models, cell-by-cell adaptive mesh refinement technique, the IAPWS-97 equation of states and its SBTL model, are combined into a numerical solver. The numerical solver incorporating these methods and models is validated with problems that possess similar physics, phase-changing process, shock-train and its interaction with shear mixing layer. Then fundamental flow physics is introduced, and general operation mode of TVC are reproduced to confirm the consistency of present computations. The influence of grid clustering level on to resolution of shear layer and computed suction performance is shown by examining grid dependence. Then simulation results on various TVC systems are compared with single- and multi-phase computations. The comparison explain the reason for yielding more accurate results by multi-phase computations than the other. Based on the computational results and comparisons, necessary of describing the phase-changing process and its influence on two major local physical features are addressed. The local flow physics are then compared between multi-phase modelings.I Introduction 1 1.1 Flow fields around TVC 1 1.2 Wetness flow and nucleation phenomenon 7 1.3 Outline of thesis 9 II Numerical approaches 11 2.1 Governing equations for multi-phase flows 11 2.2 Spatial discretization scheme 15 2.3 Compact scheme for viscous flux 19 2.4 Time integration method 21 2.5 Equation of states 25 2.5.1 IAPWS formulation 26 2.5.2 SBTL method 30 2.6 Turbulence model 38 2.6.1 The Menters kw SST turbulence model 38 2.6.2 Compressibility correction 43 2.7 Phase-changing models 44 2.7.1 Nucleation model 44 2.7.2 Hertz-Knudsen equation based-model . . . . 59 2.7.3 Difference between phase-changing models and homogeneous nucleation 63 2.8 Adaptive mesh refinement technique 64 2.9 Higher order interpolation 71 III Numerical results 73 3.1 Numerical validations 73 3.1.1 Flow inside an ejector-nozzle 73 3.1.2 Condensing flows in a nozzle 74 3.2 Flow field inside TVC 81 3.2.1 Flow physics in Thermal Vapor Compressor 83 3.2.2 Three-dimensional effects 88 3.2.3 Grid dependence and AMR technique 89 3.2.4 Phase-changing phenomena and entrainment performance 94 3.2.5 Comparison of the phase-changing models 102 IV Conclusion 108 4.1 Summary 108 4.2 Future work 111 Abstract 120Docto

Numerical Computations of Cryogenic Flows around Turbopump Induce

본 연구에서는 터보펌프 인듀서 주변의 극저온 유동장에 대한 수치해석을 주로 다룬다. 이를 위해 수치해석에 사용된 수치기법에 대한 내용을 우선 다룬다. 수치기법에 대한 검증 문제로 2차원/축대칭극저온 유동문제를 해석하였고 이 과정에서 다양한 공동모델에 대한 비교 연구를 수행하였다. 마지막으로 3차원 터보펌프 인듀서에 대한 수치해석을 수행하고, 실험 결과와 타 연구결과와 비교함과 동시에 극저온 유체에서 나타나는 공동현상의 특징을 살펴보았다.This paper deals with numerical computations of cryogenic flows around turbopump inducer. Firstly, we introduce numerical methods to compute compressible/incompressible cryogenic two-phase flow. As a validation problem, computation results of 2 dimensional/axi-symmetric cryogenic flow will be presented. In this process, various cavitation model will be compared. Finally, numerical simulation of 3 dimensional turbopump inducer will be presented.본 연구는 교육과학기술부의 우주기초원천기 술개발 사업(NSL, National Space Lab, No. 20110029871), 한국항공우주연구원의 학연협력강 화사업과 지원을 받아 이루어졌음.OAIID:oai:osos.snu.ac.kr:snu2012-01/104/0000004648/15SEQ:15PERF_CD:SNU2012-01EVAL_ITEM_CD:104USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:터보펌프_인듀서_주변_극저온_유동에_대한_수치해석_연구.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]:

Performance Prediction of Liquid Rocket Turbo-pump Inducer using a high fidelity cryogenic two-phase computation

The present paper deals with a numerical simulation of cryogenic cavitating flows around turbopump inducer in liquid rocket. Recently, we have developed an accurate and efficient baseline numerical scheme for the computations of all-speed two-phase flows. Firstly, by extending such progress, we conduct some modification of preconditioning technique and propose an accurate and efficient numerical method to deal with the computations of cryogenic two-phase flows. Secondly, we compute and compare, for the purpose of validating the proposed method, two-dimensional/axis-symmetric cryogenic cavitation flows around hydrofoil and ogive. Finally, numerical simulations of three-dimensional KARI turbopump inducer are carried out under various flow conditions with water and cryogenic fluids, and we examine the differences in inducer flow physics depending on the working fluids.본 연구는 한국연구재단을 통해 교육과학기술부의 우 주기초원천기술개발 사업(NSL, National Space Lab, 과제번호 2012-0009099) 및 항공우주신기술연구소의 지원으로부터 지원받아 수행되었음.OAIID:oai:osos.snu.ac.kr:snu2013-01/104/0000004648/2SEQ:2PERF_CD:SNU2013-01EVAL_ITEM_CD:104USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:2013우주발사체기술심포지움_김형준.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]:

Numerical investigation on cryogenic cavitating flows around turbopump inducer

This research deals with performance prediction of turbopump inducer through the two-phase flow computations. To describe the thermal effects of cryogenic fluids and two-phase flows, we used the additional governing equation for one-phase mass conservation law. As a spatial descritization scheme, RoeM for multi-phase flows are extended to treat the general equation of states, and preconditioning techniques are applied for robust and efficient computations in low-mach number region. As a validation step for such progress, two-dimensional/axi-symmetric cryogenic cavitating flows around hydrofoil and ogive are computed with different working fluids and cavitation models. Finally, numerical simulations of three-dimensional KARI turbopump inducer are carried out under various flow conditions with water and cryogenic fluids, and the differences in inducer flow physics depending on the working fluids are examined.OAIID:oai:osos.snu.ac.kr:snu2014-01/104/0000004648/2SEQ:2PERF_CD:SNU2014-01EVAL_ITEM_CD:104USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:김종암_국내학술대회_20140220_민대호.pdfDEPT_NM:기계항공공학부CONFIRM:

ALE based Fluid-Structure-Interaction Simulation of Solid Propellant Rocket

The Arbitrary Lagrangian-Eulerian(ALE, in short) method is the new description of continum motion ,which combines the advantages of the classical kinematical descriptions, i.e. Lagrangian and Eulerian description, while minimizing their respective drawbacks. In this paper, the ALE description is adapted to simulate fluid-structure interaction problems. An automatic re-mesh algorithm and a fluid-structure coupling process are included to analyze the interaction and moving motion during the 2-D axisymmetric solid rocket interior FSI phenomena simulation.본 논문은 유동과 구조물간의 상호작용으로 인해 유체나 구조, 한 쪽 분야에서의 접근으로는 한계가 있는 고체 로켓 내부 유동-구조-연소 결합 문제를 해결하기 위해 FSI를 이용한 전산해석을 목적으로 한다. ALE(Arbitrary Lagrangian Eulerian) 기술 방식을 도입하여 계산 격자의 움직임을 허용하면서도 격자에 대한 연속체 입자의 상대운동이 가능하도록 하였다. 유체 영역의 해석 프로그램은 2차원 압축성 비정상 유동 해석을 위한 오일러 방정식을 ALE 형태를 변형시켜 적용 하였고, 고체 영역의 해석 프로그램은 ALE를 고려한 2차원 동적 유한 요소 방법을 사용하였다.OAIID:oai:osos.snu.ac.kr:snu2009-01/104/0000004648/20SEQ:20PERF_CD:SNU2009-01EVAL_ITEM_CD:104USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:고체_로켓_내부_그레인_유체-구조-연소_통합_해석.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]:

Compressible-incompressible Two-phase Research of the Cryogenic Cavitation Flow about Thermal effects and several Cavitation models

일반적으로, 극저온 유체에서의 캐비테이션 현상은 상당한 온도효과와 유체 물성치의 강한 변화를 발생시킨다. 이러한 온도효과를 이해하고 정량화 하는 것은 액체 수소와 액체 산소를 가압하는 액체로켓터보시스템을 디자인하는데 중요하다. 이 현상을 정확하고 강건하게 시뮬레이션하기 위해서는, 수치 기법이 압축성-비압축성 이상유동장의 공존을 다룰 수 있어야하고, 극저온 유체의 상태방정식이 정확하게 모델링 되어야 한다. 본 연구에서는, 본 연구 그룹에서 개발한 강건한 압축성-비압축성 이상유동 수치기법이 이용되었고, regression analysis를 이용하여 상태방정식을 모델링하였다. 이를 바탕으로, 액체질소에서의 캐비테이션 현상 해석결과를 수록하였다.Generally, cavitation in cryogenic fluids generates substantial thermal effects and strong variations in fluid properties. To simulate this phenomena accurately and robustly, numerical method should be able to treat the co-existence of compressible and incompressible two-phase flow fields, and equation of state of cryogenic fluid should be accurately modeled. In this paper, a robust compressible-incompressible two-phase scheme which was developed by our research group is used and equation of state is modeled using a regression analysis. And then, numerical simulations of cavitation in liquid nitrogen are presented.본 연구는 한국연구재단을 통해 교육과학기술 부의 우주기초원천기술개발 사업(NSL, National Space Lab, 과제번호 20090091724), 2011년도 2단 계 두뇌한국21사업 및 항공우주신기술연구소의 지원으로 수행되었음.OAIID:oai:osos.snu.ac.kr:snu2011-01/104/0000004648/12SEQ:12PERF_CD:SNU2011-01EVAL_ITEM_CD:104USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:압축성-비압축성_극저온_캐비테이션_이상유동의_온도효과와_여러_가지_공동모델에_대한_연구.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]:

Efficient and Accurate Computations of Cryogenic Cavitating Flows around Turbopump Inducer

This paper deals with the numerical computations of cryogenic cavitating flows around turbopump inducer in liquid rocket. Recently, accurate and efficient baseline numerical schemes have been developed for the computations of all-speed two-phase flows. The baseline numerical schemes – RoeM and AUSMPW+ schemes for multi-phase flows – are extended for treating general equation of state, and improved preconditioning techniques are developed for more robust and efficient computations in low-speed region. As a validation step for such progress, two-dimensional/axi-symmetric cryogenic cavitating flows around hydrofoil and ogive are computed with different working fluids and cavitation models. Finally, numerical simulations of three-dimensional KARI turbopump inducer are carried out under various flow conditions with water and cryogenic fluids, and the differences in inducer flow physics depending on the working fluids are examined.OAIID:oai:osos.snu.ac.kr:snu2014-01/104/0000004648/8SEQ:8PERF_CD:SNU2014-01EVAL_ITEM_CD:104USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:전산유체학회논문_김형준.pdfDEPT_NM:기계항공공학부CONFIRM:

A new FVM-based analysis on pipeline fluid system

OAIID:oai:osos.snu.ac.kr:snu2010-01/104/0000004648/38SEQ:38PERF_CD:SNU2010-01EVAL_ITEM_CD:104USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:파이프라인_유체시스템_분석을_위한_새로운_유한체적법.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]:

Numerical Simulation for Axisymmetric Supersonic Inlet Using Orthogonal Lagrangian Formulation

본 연구는 국방과학연구소의 개발기초 연구사업(0498-20150024)과 민ㆍ군협력 기술사업(Civil-Military Technology Cooperation Program)의 지원을 받아 작성되었습니다.OAIID:RECH_ACHV_DSTSH_NO:420160000004648006RECH_ACHV_FG:RR00200003ADJUST_YN:EMP_ID:A001138CITE_RATE:FILENAME:Orthogonal_Lagrangian_Formulation을_이용한··.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]_YN:FILEURL:https://srnd.snu.ac.kr/eXrepEIR/fws/file/56fef0dc-5e58-4919-8803-cb0ca8a03745/linkCONFIRM:

Performance Prediction Study of Turbopump Inducer Through The Two-phase Flow Computations

본 연구에서는 이상유동 해석을 통한 터보펌프 인듀서의 성능 예측 연구를 주로 다룬다. 터보펌프 인듀서의 작동유체를 물 뿐만 아니라 극저온 유체에도 적용하기 위해 온도효과를 모사할 수 있는 지배방정식 및 상태방정식을 사용하였다. 또한 공동영역 주변의 압축성 영역 및 액체상 영역의 비압축성 영역을 동시에 안정적이고 효과적으로 해석할 수 있는 수치기법들을 적용하였다. 이를 통해 매질을 물로 한 경우 터보펌프 인듀서의 가압성능을 예측하고 실험 결과와 비교하였다. 또한 극저온 유체를 매질로 한 경우와의 비교를 통해 극저온 공동현상의 특징을 살펴보았다.This research deals with performance prediction of turbopump inducer through the two-phase flow computations. To describe the thermal effects of cryogenic fluids and two-phase flows, we used the additional governing equation for one-phase mass conservation law and accurate equation of states. Also we used the stable and accurate numerical schemes for cavitating flows which incompressible and compressible regimes are co-exists. As a results, we simulated cavitating flows around turbopump inducer with cold water and cryogenic fluids, and examined the differences of flow characteristics depending on the working fluids.본 연구는 교육과학기술부의 우주기초원천기술개발 사업(NSL,National Space Lab, No.20120009099)의 지원을 받아 이루어졌음.OAIID:oai:osos.snu.ac.kr:snu2013-01/104/0000004648/7SEQ:7PERF_CD:SNU2013-01EVAL_ITEM_CD:104USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:FA1-2.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]: