All Issue

2026 Vol.59, Issue 7 Preview Page
Evaluation of effective flow area in horizontal two-phase flow using frequency analysis

주파수 분석을 이용한 수평관 이상류의 유효흐름단면 해석

Chaebin Songa
,
Seongeun Kimb
,
Museop Kimc
,
Joo Suk Kod
,
Siwan Lyu,e*
송 채빈a
,
김 성은b
,
김 무섭c
,
고 주석d
,
류 시완e*
aPh.D Course, Department of Civil Engineering, Changwon National University, Changwon, Korea
bMaster's Course, Department of Civil Engineering, Changwon National University, Changwon, Korea
cMaster's Course, Department of Civil Engineering, Changwon National University, Changwon, Korea
dPh.D Research, Department of Hydro Science and Engineering Research, Korea Institute of Civil Engineering and Building Technology, Goyang, Korea
eProfessor, Department of Construction Systems Engineering, School of Green Engineering, Changwon National University, Changwon, Korea
a국립창원대학교 공과대학 토목공학과 박사과정
b국립창원대학교 공과대학 토목공학과 석사과정
c국립창원대학교 공과대학 토목공학과 석사과정
d한국건설기술연구원 수자원하천연구본부 박사후연구원
e국립창원대학교 스마트그린공학부 건설시스템공학전공 교수
*Corresponding Author
31 July 2026. pp. 691-701
PDF XML Citation
Abstract

Frequency analysis was conducted on velocity fluctuations measured in air-water mixture flowing through a horizontal pipe. The analysis was used to interpret cross-sectional flow structure and effective flow area. The velocity field was measured using Particle Image Velocimetry (PIV), and the Power Spectral Density (PSD) of the velocity fluctuations was estimated at each measurement location. A spectral energy index was defined based on the integral of PSD over the low-frequency range. The results show that the liquid-dominated and gas-dominated regions exhibited intrinsic spectral characteristics. The distribution of fluctuation energy and the characteristic location varied depending on the flow regime. Comparison with the phase boundary defined by the void fraction revealed that the two criteria reflect different physical perspectives. Although the absolute position of the phase boundary differs between the two criteria, comparable spatial variations with the flow regime were observed. These results reveal that the location of the phase boundary depends on the analysis criterion applied in the two approaches. The effective flow area contributing to actual liquid conveyance can also vary with entrained air volume. Thus, the influence of air entrainment on the flow structure should be considered in the design and hydraulic capacity evaluation of conduit systems.

Keywords
Two-phase flow
Frequency analysis
Power Spectral Density (PSD)
Void fraction
Effective flow area

본 연구는 수평관 내 물-공기 이상류에서 측정된 유속변동성분에 대한 주파수 분석을 수행하고, 이를 통해 단면 내 유동구조와 유효흐름단면 변화를 해석하였다. PIV 기법으로 측정된 유속자료를 이용하여 지점별 유속변동성분의 에너지스펙트럼밀도(Power Spectral Density, PSD)를 산정하였으며 저주파 대역의 적분값을 기반으로 에너지스펙트럼지표를 정의하였다. 분석 결과, 흐름 내 액체 지배영역과 기체 지배영역 간 상이한 스펙트럼 특성이 나타났으며 흐름양상에 따라 변동에너지의 분포와 특성위치에 차이가 나타났다. 이를 기체점유율 기준 상 경계와 비교한 결과, 두 기준은 서로 다른 물리적 관점을 반영하여 상 경계의 절대적 위치에는 차이를 보였으나 흐름양상에 따른 공간적 변화 경향은 유사하게 나타났다. 이러한 결과는 유동구조를 해석하는 기준에 따라 상 경계의 해석 결과가 달라질 수 있음을 보여주며 공기 혼입에 따라 실제 액체흐름에 기여하는 통수단면이 변화함을 시사한다. 따라서 관로시스템의 설계 및 통수능 산정 시 공기 혼입에 따른 유동구조 변화를 고려할 필요가 있다.

키워드
이상류
주파수 분석
에너지스펙트럼밀도
기체점유율
유효흐름단면
References
1

Alekseenko, S., Cherdantsev, A., Heinz, O., Kharlamov, S., and Markovich, D. (2013). “Analysis of spatial and temporal spectra of liquid film surface in annular gas-liquid flow.” Experiments in Fluids, Vol. 54, 1590. doi: 10.1007/s00348-013-1590-7.

10.1007/s00348-013-1590-7
2

Baker, O. (1954). “Simultaneous flow of oil and gas.” Oil and Gas Journal, Vol. 53, pp. 185-195.

3

Bendat, J.S., and Piersol, A.G. (2011). Random data: Analysis and measurement procedures. 4th ed., Wiley, Hoboken, NJ, U.S.

10.1002/9781118032428
4

Caldas, L., Kissner, C., Behn, M., Tapken, U., and Meyer, R. (2021). “Comparison of techniques for the estimation of flow parameters of fan inflow turbulence from noisy hot-wire data.” Fluids, Vol. 6, 372. doi: 10.3390/fluids6110372.

10.3390/fluids6110372
5

Costigan, G., and Whalley, P.B. (1997). “Slug flow regime identification from dynamic void fraction measurements in vertical air-water flows.” International Journal of Multiphase Flow, Vol. 23, No. 2, pp. 263-282. doi: 10.1016/S0301-9322(96)00050-X.

10.1016/S0301-9322(96)00050-X
6

Foucaut, J.M., Carlier, J., and Stanislas, M. (2004). “PIV optimization for the study of turbulent flow using spectral analysis.” Measurement Science and Technology, Vol. 15, pp. 1046-1058. doi: 10.1088/0957-0233/15/6/003.

10.1088/0957-0233/15/6/003
7

Khan, U., Pao, W., and Sallih, N. (2023). “Numerical gas-liquid two-phase flow regime identification in a horizontal pipe using dynamic pressure data.” Applied Sciences, Vol. 13, 1225. doi: 10.3390/app13021225.

10.3390/app13021225
8

Lee, K., Cho, H., Rhee, D.S., and Lyu, S. (2018). “Experimental investigation on the velocity structure and its effect on the flow patterns of air-water two-phase flow in a horizontal pipe.” KSCE Journal of Civil Engineering, Vol. 22, No. 9, pp. 3363-3372, doi: 10.1007/s12205-018-1037-z.

10.1007/s12205-018-1037-z
9

Raffel, M., Willert, C., and Kompenhans, J. (2007). Particle image velocimetry: A practical guide. Springer, Berlin, Germany.

10.1007/978-3-540-72308-0
10

Riverin, J.L., de Langre, E., and Pettigrew, M.J. (2006). “Fluctuating forces caused by internal two-phase flow on bends and tees.” Journal of Sound and Vibration, Vol. 298, pp. 1088-1098. doi: 10.1016/j.jsv.2006.06.039.

10.1016/j.jsv.2006.06.039
11

Sikora, M., Anweiler, S., and Meyer, J. (2024). “Comprehensive analysis of two-phase liquid-gas flow structures in varied channel geometries and thermal environments.” International Journal of Heat and Mass Transfer, Vol. 228, 125665. doi: 10.1016/j.ijheatmasstransfer.2024.125665.

10.1016/j.ijheatmasstransfer.2024.125665
12

Song, C. (2026). An experimental study on the dynamics of horizontal pipe flow with air entrainment. Master Thesis, Changwon National University, pp. 54-58.

13

Song, C., Kim, S., Kim, M., and Lyu, S. (2026). “An experimental study on gas behavior and effective flow area for liquid in horizontal two-phase flow.” Journal of Korea Water Resources Association, Vol. 59, No. 1, pp. 51-64. doi: 10.3741/JKWRA.2026.59.1.51.

10.3741/JKWRA.2026.59.1.51
14

Song, C., Ko, J.S., Choi, S.H., and Lyu, S. (2025). “Velocity structure measurement for water flow with air bubbles in a horizontal pipe.” Proceedings of the 41st IAHR Congress, Singapore, pp. 2296-2298.

15

Yih, T. S., and Griffith, P. (1970). “Unsteady momentum fluxes in two-phase flow and the vibration of nuclear system components.” Proceedings of the International Conference on Flow-Induced Vibrations in Reactor System Components, Lemont, IL, U.S., pp. 91-111.

Information
  • Publisher :KOREA WATER RESOURECES ASSOCIATION
  • Publisher(Ko) :한국수자원학회
  • Journal Title :Journal of Korea Water Resources Association
  • Journal Title(Ko) :한국수자원학회 논문집
  • Volume : 59
  • No :7
  • Pages :691-701
  • Received Date : 2026-03-31
  • Revised Date : 2026-05-08
  • Accepted Date : 2026-05-08
  • DOI :https://doi.org/10.3741/JKWRA.2026.59.7.691
Journal Informaiton Journal of Korea Water Resources Association Journal of Korea Water Resources Association
Online Submission
Archives
  • scopus
  • KCI-수자원
  • NRF
  • KOFST
  • KISTI Current Status
  • KISTI Cited-by
  • crosscheck
  • orcid
  • open access
  • ccl
Journal Informaiton Journal Informaiton - close