• Title/Summary/Keyword: Thermal Analysis

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A Study of High-Power Dissipation Parts Modeling for Spacecraft PCB Thermal Analysis (위성 PCB 열해석을 위한 고 전력소산 소자의 모델링 연구)

  • 이미현;장영근;김동운
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.6
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    • pp.42-50
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    • 2006
  • This paper addresses the optimized thermal modeling methodology for spacecraft board level thermal analysis. A direct thermal modeling of external and internal structure of active parts which have high power dissipation is newly proposed, based on conventional plate modeling for Printed Circuit Board(PCB). The parts thermal modeling results were compared with other generic methodologies and verified by thermal vacuum test. This parts thermal modeling was directly applied to thermal analysis of CS(Communication Subsystem) board of HAUSAT-2 small satellite. As a result, it was confirmed that the parts thermal modeling can complement other conventional modeling methodologies. A parts thermal modeling is very effective for thermal control design, since the existing thermal problems can be solved at the parts level in advance.

Residual Stress Measurement of Sand Casting by ESPI Device and Thermal Stress Analysis (ESPI 장비를 활용한 사형 주조품의 잔류응력 측정 및 주조 열응력 해석)

  • Kwak, Si-Young;Nam, Jeong-Ho
    • Journal of Korea Foundry Society
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    • v.40 no.1
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    • pp.1-6
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    • 2020
  • Many studies involving a thermal stress analysis using computational methods have been conducted, though there have been relatively few experimental attempts to investigate thermal stress phenomena. Casting products undergo thermal stress variations during the casting process as the temperature drops from the melting temperature to room temperature, with gradient cooling also occurring from the surface to the core. It is difficult to examine thermal stress states continuously during the casting process. Therefore, only the final states of thermal stress and deformations can be detemined. In this study, specimens sensitive to thermal stress, were made by a casting process. After which the residual stress levels in the specimens were measured by a hole drilling method with Electron Speckle-Interferometry technique. Subsequently, we examined the thermal stresses in terms of deformation during the casting process by means of a numerical analysis. Finally, we compared the experimental and numerical analysis results. It was found that the numerical thermal stress analysis is an effective means of understanding the stress generation mechanism in casting products during the casting process.

Thermal Pointing Error Analysis of Satellite (인공위성 열지향오차 해석)

  • Kim, Seon-Won;Kim, Jin-Hui;Lee, Jang-Jun;Hwang, Do-Sun
    • Journal of Satellite, Information and Communications
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    • v.2 no.1
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    • pp.21-26
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    • 2007
  • LEO Satellite that observes earth with optical camera or synthetic aperture radar is placed at hundreds of kilometers altitude and undergoes severe thermal load. The thermal deformation of structure by the thermal load makes payload not to point toward wanted ground position. The payload pointing direction change by thermal distortion is called thermal pointing error. This is carried out by 3 steps that are thermal analysis, temperature conversion and structural analysis. In this paper, the possibility of successful mission through thermal pointing error analysis is described.

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PRELAUNCH THERMAL ANALYSIS OF KSLV-I PAYLOAD FAIRING

  • Choi Sang-Ho;Kim Seong-Lyong;Kim Insun
    • Bulletin of the Korean Space Science Society
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    • 2004.10b
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    • pp.356-359
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    • 2004
  • Prelaunch thermal analysis of the KSLV (Korea Space Launch Vehicle)-I PLF (Payload Fairing) was performed to predict maximum/minimum liftoff temperatures and to evaluate of air conditioning performance. Prelaunch thermal analysis includes internal air conditioning effect, external convective heating/cooling, radiation exchange with the ground and sky, radiation between spacecraft and PLF, and solar radiation incident on PLF. Analysis was performed at two extreme conditions, hot day condition and cold day condition. The results showed that the maximum liftoff temperature was $53^{\circ}C$ and the minimum liftoff temperature was $-3.8^{\circ}C$. It was also found that conditioned air supplying, in $20{\pm}2^{\circ}C\;and\;1200\;m^3/hr$, is sufficient to keep the internal air in required temperature range.

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Development of Thermal Distortion Analysis Method on Large Shell Structure Using Inherent Strain as Boundary Condition (고유변형도를 경계조건으로 갖는 대형 각(殼) 구조물 열변형 해석법 개발)

  • Ha, Yun-Sok
    • Journal of the Society of Naval Architects of Korea
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    • v.45 no.1
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    • pp.93-100
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    • 2008
  • There are two ways of conventional thermal distortion analysis. One is the thermal elasto-plastic analysis and the other is the equivalent forces method based on inherent strain. The former needs exorbitant analysis time, while the latter cannot obtain results of stress field and it needs much time consumption with loads modeling on curved plates. Such faults in two methods have made difficulties in thermal distortion analysis of a large structure like ship hull. In order to solve them, new kind of thermal distortion analysis method was developed. We devised that the inherent strains was used as direct input factors in forms of boundary conditions. It was embodied by using thermal expansion coefficient in commercial code. We used the pre-calculated inherent strain as thermal expansion coefficient, and endowed nodes with imaginary temperatures. This method was already adopted at hull block welding distortion analysis which was considered as impossible, and gave productive results such as reduction of work time in the dry dock.

A Study on Thermal Analysis in Ventilated Disk Brake by FEM (FEM을 이용한 벤틸레이티드 디스크 브레이크 열응력 해석에 관한 연구)

  • Kim, Sung-Mo
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.18 no.5
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    • pp.544-549
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    • 2009
  • Thermal brake judder caused by the high friction heat of the brake disk. Hot thermal judder makes serious problems such as to be unstability to drivers or to decrease braking force of automobile. Because thermal judder vibration makes high vibration occurrence and thermal deformation of brake disk. Therefore it Is necessary to reduce or eleminate thermal Judder phenomenon by understanding and investigation. This paper introduces the thermal deformation arising from friction heat generation in braking and proposes the FEM analysis to predict the distribution of temperature and thermal deformation. the results of the FEM analysis show the deformed shape and temperature distribution of the disk brake. The optimization is performed to minimize the thermal judder of ventilated disc brake that is induced by the thermal deformation of the disk brake.

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A Study on Optimized Thermal Analysis Modeling for Thermal Design Verification of a Geostationary Satellite Electronic Equipment (정지궤도위성 전장품의 열설계 검증을 위한 최적 열해석 모델링 연구)

  • Jun Hyoung Yoll;Yang Koon-Ho;Kim Jung-Hoon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.4 s.235
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    • pp.526-536
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    • 2005
  • A heat dissipation modeling method of EEE parts, or semi-empirical heat dissipation method, is developed for thermal design and analysis an electronic equipment of geostationary satellite. The power consumption measurement value of each functional breadboard is used for the heat dissipation modeling method. For the purpose of conduction heat transfer modeling of EEE parts, surface heat model using very thin ignorable thermal plates is developed instead of conventional lumped capacity nodes. The thermal plates are projected to the printed circuit board and can be modeled and modified easily by numerically preprocessing programs according to design changes. These modeling methods are applied to the thermal design and analysis of CTU (Command and Telemetry Unit) and verified by thermal cycling and vacuum tests.

Thermal Analysis of APD Electronics for Activation of a Spaceborne X-band 2-axis Antenna (위성 데이터 전송용 2축 짐벌식 X-band 안테나 구동용 전장품 APD 열 해석)

  • Ha, Heon-Woo;Kang, Soo-Jin;Kim, Tae-Hong;Oh, Hyun-Ung
    • Journal of Aerospace System Engineering
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    • v.10 no.2
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    • pp.1-6
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    • 2016
  • The thermal analysis of electronic equipment is required to predict the reliability of electronic equipment being loaded on a satellite. The transient heat transfer of electronic equipment that was developed recently has been generated using a large-scale integration circuit. If there is a transient heat transfer between EEE(Electric, Electronic and Electro mechanical) parts, it may lead to failure the satellite mission. In this study, we performed the thermal design and analysis for reliability of APD(Antenna Pointing Driver) electronics for activation of a spaceborne X-band 2-axis antenna. The EEE parts were designed using a thermal mathematical model without the thermal mitigation element. In addition, thermal analysis was performed based on the worst case for verifying the reliability of EEE parts. For the thermal analysis results, the thermal stability of electronic equipment has been demonstrated by satisfying the de-rating junction temperature.

Spacecraft Radiator Design Optimization Approach of Combining Optimization Algorithm with Thermal Analysis (최적화알고리즘과 열해석을 통합한 위성방열판 설계의 최적화 방법에 관한 연구)

  • Kim, Hui-Kyung
    • Aerospace Engineering and Technology
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    • v.12 no.2
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    • pp.24-29
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    • 2013
  • A spacecraft radiator is a thermal control method to eject internally dissipated heat into the space generated from operation of unit boxes. The efficiency of thermal design may be improved by optimizing radiator design. In this paper, the optimization approach method of node-based radiator design was suggested which is to combine numerical thermal analysis with optimization algorithm. This method has meaning that it can be used practically to implement the spacecraft radiator design regardless of thermal analysis and optimization algorithm software and maintain the same basic concept of an ordinary radiator design approach based on node division of a thermal model. The overall analysis framework with thermal analysis and optimization algorithm would be presented.

Thermal-Mixing Analyses for Safety Injection at Partial Loop Stagnation of a Nuclear Power Plant

  • Hwang, Kyung-Mo;Kim, Kyung-Hoon
    • Journal of Mechanical Science and Technology
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    • v.17 no.9
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    • pp.1380-1387
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    • 2003
  • When a cold HPSI (High pressure Safety Injection) fluid associated with an overcooling transient, such as SGTR (Steam Generator Tube Rupture), MSLB (Main Steam Line Break) etc., enters the cold legs of a stagnated primary coolant loop, thermal stratification phenomena will arise due to incomplete mixing. If the stratified flow enters the downcomer of the reactor pressure vessel, severe thermal stresses are created in a radiation embrittled vessel wall by local overcooling. As general thermal-hydraulic system analysis codes cannot properly predict the thermal stratification phenomena, RG 1.154 requires that a detailed thermal-mixing analysis of PTS (pressurized Thermal Shock) evaluation be performed. Also. previous PTS studies have assumed that the thermal stratification phenomena generated in the stagnated loop side of a partially stagnated primary coolant loop are neutralized in the vessel downcomer by the strong flow from the unstagnated loop. On the basis of these reasons, this paper focuses on the development of a 3-dimensional thermal-mixing analysis model using PHOENICS code which can be applied to both partial and total loop stagnated cases. In addition, this paper verifies the fact that, for partial loop stagnated cases, the cold plume generated in the vessel downcomer due to the thermal stratification phenomena of the stagnated loop is almost neutralized by the strong flow of the unstagnated loop but is not fully eliminated.