Journal of Korea Water Resources Association (한국수자원학회논문집)

Korea Water Resources Association (한국수자원학회)
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Experimental study of the air emission effect in the tangential and the multi-stage spiral inlet

접선식 유입구와 다단식 나선 유입구의 공기 배출 효과에 관한 실험적 연구

  • Seong, Hoje (Department of Land, Water and Environment Research, Korea Institute of Civil Engineering and Building Technology) ;
  • Rhee, Dong Sop (Multi Disaster Countermeasures Organization, Korea Institute of Civil Engineering and Building Technology) ;
  • Park, Inhwan (Department of Land, Water and Environment Research, Korea Institute of Civil Engineering and Building Technology)
  • 성호제 (한국건설기술연구원 국토보전연구본부) ;
  • 이동섭 (한국건설기술연구원 복합재난대응연구단) ;
  • 박인환 (한국건설기술연구원 국토보전연구본부)
  • Received : 2019.01.10
  • Accepted : 2019.02.15
  • Published : 2019.04.30
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Abstract

Recently, urban inundation was frequently occurred due to the intensive rainfall exceeding marginal capacity of the flood control facility. Furthermore, needs for the underground storage facilities to mitigate urban flood are increasing according to rapidly accelerating urbanization. Thus, in this study, drainage efficiency in drain tunnel connecting to underground storage was investigated from the air-core measurements in the drop shaft against two types of inlet structure. In case of the spiral inlet, the multi-stage structure is introduced at the bottom of the inlet to improve the vortex induction effect at low inflow discharge (multi-stage spiral inlet). The average cross-sectional area of the air-core in the multi-stage spiral inlet is 10% larger than the tangential inlet, and show the highly air emission effect and the highly inflow efficiency at the high inflow discharge. In case of the tangential inlets, the air emission effect decreased after exceeding the maximum inflow discharge, which is required to maintain the inherent performance of the tangential inlet. From the measurements, the empirical formula for the cross-sectional area of the air-core according to locations inside the drop shaft was proposed in order to provide the experimental data available for the inlet model used in experiments.

급격한 기상변화로 인한 극한 강우와 집중폭우의 발생빈도 증가로 기존 수방시설의 한계 용량을 초과해 도심지 침수피해가 빈번하게 발생하고 있다. 최근 도시화 추세가 급격하게 빨라지면서 수방시설 등 사회기반시설에 대한 지하공간 개발의 필요성이 증가하고 있으며, 지하공간을 활용한 지하방수로와 지하저류지 기술이 급부상하고 있다. 본 연구에서는 지하유입시설의 대표적 형상인 접선식 유입구와 나선식 유입구에 대한 공기 배출효과를 분석하기 위해 유입유량 변화에 따른 수직갱 내부 공기공동(air-core)의 형상 크기를 계측했다. 나선식 유입구의 경우, 저유량 유입조건에서 와류 유도 효과를 개선하기 위해 유입부 바닥면에 계단형 다단식 구조를 도입했다. 수직갱 내부 공기공동의 전체적인 평균 단면적의 경우, 다단식 나선 유입구가 접선식 유입구보다 10% 정도 크게 나타나 고유량 유입조건에서 높은 공기 배출 효과와 유입효율을 나타냈다. 접선식 유입구의 경우, 유입구가 가지는 고유 성능을 유지할 수 있는 최대 유량 조건을 초과하면서 공기 배출 효과가 감소하기 시작했다. 또한, 실험에서 사용된 접선식 유입구와 다단식 나선 유입구 모형에 활용 가능한 기초자료를 제공하기 위해 수직갱 내부 위치에 따른 공기공동 단면적에 대한 실험식(empirical formula)을 제시했다.

Keywords

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Fig. 1. Descriptions of the tangential inlet

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Fig. 2. Descriptions of the spiral inlet

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Fig. 3. Descriptions of the multi-stage spiral inlet

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Fig. 4. Outlines of the experiment channel

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Fig. 5. Measuring instruments for the air-core size

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Fig. 6. Experimental model of inlet structures

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Fig. 7. Air-core size measurement points in the drop shaft

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Fig. 8. Measuring points to investigate the air-core size

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Fig. 9. Shape of the air-core according to the inflow discharge

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Variations of Aa /Ad against the vertical location in the drop shaft

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Fig. 11. Comparisons of Aam /Ad according to inlet structures

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Fig. 12. Comparisons of Aaa /Ad according to inlet structures

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Fig. 13. Comparison of the empirical formula results and the measurements

Table 1. Experimental conditions

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