• Title/Summary/Keyword: 부 압력단계

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Application of Computational Fluid Dynamics to Development of Combustion Devices for Liquid-Propellant Rocket Engines (액체추진제 로켓 엔진 연소장치 개발에 있어서의 전산유체역학 응용)

  • Joh, Miok;Kim, Seong-Ku;Han, Sang Hoon;Choi, Hwan Seok
    • Aerospace Engineering and Technology
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    • v.13 no.2
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    • pp.150-159
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    • 2014
  • This study provides a brief introduction to application of the computational fluid dynamics to domestic development of combustion devices for liquid-propellant rocket engines. Multi-dimensional flow analysis can provide information on the flow uniformity and pressure loss inside the propellent manifold, from which the design selection can be performed during the conceptual design phase. Multi-disciplinary performance analysis of the thurst chamber can also provide key information on performance-related design issues such as fuel film cooling and thermal barrier coating conditions. Further efforts should be made to develop numerical models to resolve the mixing and combustion characteristics of LOX/kerosene near the injection face plate.

고진공펌프의 상태진단 시스템

  • Jeong, Wan-Seop;Nam, Seung-Hwan;Kim, Wan-Jung;Im, Jong-Yeon
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.08a
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    • pp.101-101
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    • 2012
  • 본 논문은 현재 제품화 단계로 진행 중인 터보 분자펌프(turbo-molecular pump, TMP)와 극저온 펌프(cryopump)의 고장 방지 및 예지 보수를 위한 상태 진단 시스템에 대하여 소개를 한다. 본 상태 진단 시스템은 고진공 펌프들의 다중 상태변수 즉 흡/배기부의 진공 압력, 부위별 온도, 소비 전류(혹은 전력), 그리고 부위별 진동 신호들을 실시간으로 측정하는 상태변수 수집장치, 수집된 시계열 상태변수들이 저장된 database, 그리고 저장된 상태변수를 이용한 고진공펌프의 상태진단 프로그램으로 구성되어 있다. 금번 연구에서 구축한 상태변수 체계의 특징 중 하나는 진동신호를 상태변수로 측정하여 이를 상태진단에 활용하는 점이 기존의 접근방법과 상이한 점이다. 실시간 신호 수집장치는 NI사 PXI 시스템 기반의 16채널 24-bit 동시 전압신호 측정 모듈, 8부위의 온도 측정장치(Lakeshore 218S, RS-232C 통신), 그리고 펌프의 소비전류/전력 측정장치(Hioki 3169, RS-232C), 그리고 고진공 펌프의 흡입 및 배기구의 진공도 측정장치로 구성하였다. 신호 수집용 프로그램은 NI사 Labview를 이용하여 작성하였다. 본 장치는 Nano-Fab 센터의 협조 하에 turbo-molecular 펌프와 cryopump측정 단에 각각 1대를 설치 완료하였으며 현재까지 운용 중이다. PC에 저장된 시계열 상태변수 database는 기 개발된 적응형 인자모델을 이용한 매개변수로 변환되며, 상태진단은 변환된 매개변수를 이용하여 수행할 예정이다.

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Reflood Experiments with Horizontal and Vertical Flow Channels

  • Chung, Moon-Ki;Lee, Seung-Hyuck;Park, Choon-Kyung;Lee, Young-Whan
    • Nuclear Engineering and Technology
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    • v.12 no.3
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    • pp.153-162
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    • 1980
  • The investigation of the fuel cladding temperature behavior and heat transfer mechanism during the reflooding phase of a LOCA plays an important role in performance evaluation of ECCS and safety analysis of water reactors. Reflooding experiments were performed with horizontal and vertical flow channels to investigate the effect of coolant flow channel orientation on rewetting process. Emphasis was mainly placed on the CANDU reactor which has horizontal pressure tubes in core, and the results were compared with those of vertical channel. Also to investigate the rewetting process visually, the experiments by using a rod in annulus and a quartz tube heated outside were performed. It can be concluded that the rewetting velocity in horizontal flow channel is clearly affected by flow stratification, however, the average rewetting velocity is similar to those in vertical flow channel for same conditions.

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Conceptual Design and Manufacturing Scheme of a Gas Generator for 7 tonf Class Rocket Engine (7톤급 로켓엔진 가스발생기 개념설계 및 제작계획)

  • Lim, Byoung-Jik;Kim, Moon-Ki;Kang, Dong-Hyuk;Choi, Hwan-Seok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2012.05a
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    • pp.451-453
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    • 2012
  • Conceptual design and manufacturing scheme of a gas generator for 7 tonf class rocket engine were described. The combustion chamber pressure, O/F ratio, and total flow rate were decided to be 6 MPa, 0.321, and 1 kg/s respectively in consequence of the engine system design. Based on the parameters conceptual design of the gas generator was carried out and its outer dimension was about ${\Phi}100{\times}250mm$. Most parts of the gas generator to be jointed together by brazing or TIG welding and, if possible, the strength and leakproof tests are to be conducted in every step for checking the welding section.

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Techno-economic Analysis and Environmental Impact Assessment of a Green Ammonia Synthesis Process Under Various Ammonia Liquefaction Scenarios (암모니아 액화 시나리오에 따른 그린암모니아 합성 공정의 경제성 및 환경 영향도 평가)

  • Gunyoung Kim;Yinseo Song;Boram Gu;Kiho Park
    • Korean Chemical Engineering Research
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    • v.62 no.2
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    • pp.163-172
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    • 2024
  • In this study, two different scenarios for ammonia liquefaction in the green ammonia manufacturing process were proposed, and the economic-feasibility and environmental impact of each scenario were analyzed. The two liquefaction processes involved gas-liquid separation before cooling at high pressure (high pressure cooling process) or after decompression without the gas-liquid separation (low pressure cooling process). The high-pressure cooling process requires higher capital costs due to the required installation of separation units and heat exchangers, but it offers relatively lower total utility costs of 91.03 $/hr and a reduced duty of 2.81 Gcal/hr. In contrast, although the low-pressure cooling process is simpler and cost-effective, it may encounter operational instability due to rapid pressure drops in the system. Environmental impact assessment revealed that the high-pressure cooling process is more environmentally friendly than the low-pressure cooling process, with an emission factor of 0.83 tCO2eq less than the low-pressure cooling process, calculated based on power usage. Consequently, the outcomes of this study provide relevant scenario and a database for green ammonia synthesis process adaptable to various process conditions.

Response Characteristics of the HIL System for Passenger Diesel Engine (승용 디젤엔진 HIL 시스템의 응답 특성)

  • Chung, Jin-Eun;Roh, Ho-Jong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.11
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    • pp.4745-4750
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    • 2011
  • A HIL(hardware-in-the-loop) system was established and the simulation was carried out to determine whether the system operates normally. The system consists of turbocharger test bench, HIL platform with real time S/W and DAQ, and engine model using Matlab/Simulink. In the simulation the supplied fuel rate is changed step-by-step from 1.8944 kg/h to 4.7360 kg/h. The change of air-fuel ratio is analyzed and observed whether the air-fuel ratio follow the target air-fuel ratio 32. When the supplied fuel rate is changed, the air-fuel ratio is converged to the target air-fuel ratio after about 20 seconds. And the vane duty ratio of turbine and the boost pressure of compressor are also changed properly. Therefore this HIL system can be used to develop the new turbocharger and improve the performance of the modified turbocharger.

Development of numerical method to predict broadband radiation noise resulting in fluid-induced vibration and acoustic-induced vibration of pipe (배관의 유동 유발 진동 및 음향 유발 진동 기인 광대역 방사 소음 예측을 위한 수치 해석 기법 개발)

  • Sangheon Lee;Cheolung Cheong;Songjune Lee
    • The Journal of the Acoustical Society of Korea
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    • v.43 no.1
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    • pp.112-121
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    • 2024
  • The pipping system is widely used in many industries as equipment for transporting fluids over long distances. In high-pressure pipe, as the speed of the fluid increases, a loud noise is generated. Therefore, various studies have been conducted to reduce pipe noise. In this paper, a pipe noise analysis was developed to predict and quantitatively assess the flow-induced vibration and acoustic-induced vibration due to valve flow in high-temperature and high-pressure. To do this, a high-fidelity fluid analysis technique was developed for predicting internal flow in the pipe with valve. In additional, the contribution of compressible/incompressible pressure by frequency band was evaluated using the wavenumber-frequency analysis. To predict a low/middle frequency pipe noise, the vibroacoustic analysis method was developed based on Finite Element Method (FEM). And the pipe noise prediction method for the middle/high frequency was developed based on Statistical Energy Analysis (SEA).

Study on the simulation of a spark ignition engine using BOOST (상용 소프트웨어를 이용한 스파크 점화 기관의 시뮬레이션에 관한 연구)

  • Jeong, Chang-Sik;Woo, Seok-Keun;Ryu, Soon-Pil;Yoon, Keon-Sik
    • Journal of Advanced Marine Engineering and Technology
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    • v.40 no.9
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    • pp.733-742
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    • 2016
  • In recent years, gas engines fueled with LNG or synthetic gas have been attracting considerable attention for marine use owing to their potential to facilitate better fuel economy and to reduce emissions. It has been confirmed that gas engines using the Otto cycle, which involves premixed combustion, can satisfy Tier III regulations without the EGR or SCR system. The objective of this study is to acquire simulation technologies for predicting gas engine performances in industrial fields. Using the commercial software BOOST, the simulation is conducted on a gasoline engine rather than a marine engine due to the gasoline engine's easier accessibility. This study consists of two stages. In the first stage published previously, the optimal modeling techniques for representing the behavior of the gas in the intake and exhaust systems were determined. In the current study, we formulated a method to evaluate the combustion and heat transfer processes in the cylinder and to ultimately determine the major performance parameters, given that the analytical model derived from the previous stage has been applied. Through this study, we were able to determine a combustion and heat transfer model and a valve discharge coefficient that are less reliant on empirical data: we were also able to formulate a methodology through which relevant constants are decided. We confirmed that the values of transient cylinder pressure variation, indicated mean effective pressure, and air supply can be successfully predicted using our modeling techniques.

Numerical Simulation of Spatiotemporal Distribution of Chaff Clouds for Warship Defense using CFD-DEM Coupling (CFD-DEM 연동을 통한 함정용 채프운의 시공간 분포 해석)

  • Uk Jin Jung;Moonhong Kim;Dongwoo Sohn
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.36 no.2
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    • pp.93-103
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    • 2023
  • Warships widely spread numerous chaffs using a blast, which form chaff clouds that create false radar cross-sections to deceive enemy radars. In this study, we established a numerical framework based on a one-way coupling of computational fluid dynamics and discrete element method to simulate the spatiotemporal distribution of chaff clouds for warships in the air. Using the framework, we investigated the effects of wind, initial chaff cartridge angle, and blast pressure on the distribution of chaff clouds. We observed three phases for the chaff cloud diffusion: radial diffusion by the explosion, omnidirectional diffusion by turbulence and collision, and gravity-induced diffusion by the difference in the fall speed. The wind moved the average position of the chaff clouds, and the diffusion due to drag force did not occur. The direction of radial diffusion by the explosion depended on the initial angle of the cartridge, and a more vertical angle led to a wider distribution of the chaffs. As the blast pressure increased, the chaff clouds spread out more widely, but the distribution difference in the direction of gravity was not significant.

The crenulation of Ogcheon metasedimentary rocks near the Ogcheon granite and the Honam shearing, Korea (옥천화강암 부근 옥천 변성퇴적암류의 파랑습곡구조와 호남전단운동)

  • Kang, Ji-Hoon
    • The Journal of the Petrological Society of Korea
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    • v.19 no.2
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    • pp.157-165
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    • 2010
  • The age unknown Ogcheon metasedimentary rocks and the Jurassic Ogcheon granite (Jocgr) intruding it are distributed in the Ogcheon area, which is located in the central part of the Ogcheon Belt, Korea, This paper newly examines the timing of Honam shearing on the basis of the microstructural researches on time-relationship between the crenulation of Ogcheon metasedimentary rocks and the contact metamorphism by the intrusion of Jocgr. The D2 crenulation phase, which is defined by the microfolding of the S1 foliation in the metasedimentary rocks, is divided into two sub-phases. The one is a sub-phase of Early crenulation (D2a) which is included within old andalusite porphyroblasts, and the other is that of Late crenulation (D2b) which warps around the old andalusite. But they show the same dextral shear sense, the axial planes parallel to each other, and a single crenulation at outcrop scale. The contact metamorphism of andalusite-sillimanite type by the Jocgr occurred during the inter-phases of D2a and D2b, and crystallized the old andalusite masking the D2a crenulation and fibrous sillimanites replacing the D2a crenulation-forming muscovites. New andalusite porphyroblasts synkinematically grew in pressure shadows around the old andalusite or in its outermost mantles during the early stage of the D2b. The D2b occurred still continuously after the growth of the andalusite ceased (= later stage of the D2b). It indicates that the D2b occurred continuously during the period when the Ogcheon granite was still hot and cool. From this study, the crenulation history of Ogcheon metasedimentary rocks and the timing of Honam shearing would be newly established and reviewed as follows. (1) Early Honam shearing; formative period of Early crenulation, (2) main magmatic period of Jurassic granitoids; growth of the old andalusite and fibrous sillimanite by the intrusion of Jocgr, (3) main cooling period of Jurassic granitoids; formative period of Late crenulation related to Late Honam shearing, growth of the new andalusite in the early stage of D2b. Thus, this study proposes that the Honam shear movement would occur two times at least before and after the intertectonic phase which corresponds to the main magmatic period of Jurassic granitoids.