고압 수증기 안전밸브에 관한 유동해석적 연구

다국어 초록 (Multilingual Abstract)

A Study on the Fluid Analysis of
High-Pressure Steam Safety Valve
Choi, Kwangho
Department of Eco-Friendly Smart Marine Equipment
Graduate School of Maritime Industries
Korea Maritime & Ocean University
Abstract
Spring-type safety valves installed on conventional high-pressure pipelines offer si
mplicity and high reliability; however, as ship and power-plant systems continue to
increase in pressure and capacity, the limitations of this type have become appare
nt. In particular, under high-temperature and high-pressure conditions, thermal eff
ects on the spring and cyclic fatigue can cause variations in set pressure, potentia
lly leading to malfunction and reduced safety during long term operation. Therefor
e, the application of pilot-operated safety valves (POSRVs) is essential for high-pr
essure service.
This study aims to verify the design and analyze the performance of
high-pressure steam safety valves by investigating internal flow characteristics,
noise, and vibration of the main valve in a POSRV using Computational Fluid
Dynamics (CFD). For this study numerous simulations were performed to evaluate
pressure, velocity, and acoustic behavior within the main valve and identify
turbulence, vortex formation, pressure drop, and noise-generation mechanisms duri
ng entire the valve opening and closing process. The flow analysis results show
that when a high inlet pressure of 16.85 MPa(110% of the set pressure) is applied
the flow accelerates dramatically toward the outlet with valve open. A significant
pressure drop and high-velocity jet(maximum velocity approximately 320 m/s) were
observed near the perforated region on above part of the outlet flange, where
vortex structures and partial backflow were generated. This region exhibited
concentrated increase in turbulent kinetic energy, indicating a major source of Ac
oustic analysis using the Broadband Noise Model revealed that noise levels
increased rapidly at the initial stage of valve opening, reaching approximately 113.4
dB at the analysis pressure of 16.85 MPa, and then gradually decreased when the
mass flow stabilized. Structural analysis showed that the main valve body
experienced a maximum stress of 330 MPa and a maximum displacement of 0.07
mm under the maximum operating pressure. A safety factor greater than 4 was
secured relative to the material’s yield strength. Additionally, potential resonance
was identified within the vibration frequency range induced by internal flow (500–
600 Hz). This study provides design improvement guidelines for reducing noise and
vibration in POSRVs operating with high-pressure steam. The results are expected
to be fundamental data for ensuring durability in pilot-operated safety valves
applied in ships, power plants, submarines, and other systems exposed to
high-pressure or high-temperature environments

목차 (Table of Contents)

• List of Tables iii
• List of Figures iii
• Abstract iv
• 제 1 장 서론 1
• 1.1 연구배경 및 필요성 1
• 1.2 연구내용 4
• 제 2 장 CFD 해석관련 이론 7
• 2.1 압축성유체의 특성 7
• 2.2 지배방정식 9
• 2.3 진동해석 이론 21
• 제 3 장 모델링 22
• 3.1 실제 형상 22
• 3.2 형상 단순화 23
• 3.3 메쉬 구성 및 해석모델링 25
• 3.4 메쉬 모션 28
• 3.5 솔버 설정 30
• 제 4 장 유동해석 결과 33
• 4.1 압력 33
• 4.2 속도 35
• 4.3 속도 벡터 36
• 4.4 부피분율 38
• 4.5 소음 39
• 제 5 장 구조해석 결과 41
• 5.1 응력 41
• 5.2 자유진동 44
• 제 6 장 결론 47
• 참고문헌 49