Journal of Korea Water Resources Association (한국수자원학회논문집)

Korea Water Resources Association (한국수자원학회)
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An experimental investigation of flow characteristics in the tangential and the multi-stage spiral inlets

접선식 및 다단식 나선 유입구 흐름 특성의 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 : 2019.01.02
  • Accepted : 2019.02.14
  • Published : 2019.03.31
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Abstract

The vulnerability of urban disasters is increased with the rapid urbanization and industrialization, and the extreme rainfall event is increased due to the global climate change. Urban inundation is also increased due to the extreme rainfall event beyond the capacity limit of facility for the damage prevention. The underground detention vault and the underground drain tunnel are rapidly being utilized to prevent urban inundation. Therefore, the hydraulic review and design analysis of the inlet of the underground facility are important. In this study, the water level of the approach flow according to the inflow discharge is measured and the flow characteristic of the inlet (tangential and spiral) is analyzed. For the spiral inlet, the multi-stage is introduced at the bottom of the inlet to improve the inducing vortex flow at low discharge conditions. In case of the tangential inlet, the discharging efficiency is decreased rapidly with hydraulic jump in the high flow discharge. The rising ratio of the water level in the multi-stage spiral inlet is higher than the tangential inlet, but the stable discharging efficiency is maintained at low and high discharge conditions. And the empirical formula of water level-flow discharge is derived in order to utilize inlets used in this study.

급격한 도시화와 산업화로 도심 재난 취약성이 증가하고, 전 세계적인 기후변화로 인한 극한 강우사상의 발생빈도가 증가하고 있다. 기존 방재시설의 용량한계를 넘어선 극한 강우사상의 발생으로 도심 지역의 침수피해 또한 증가하고 있다. 도심 침수피해를 예방하기 위해 지하공간을 활용한 지하저류 시설과 지하배수터널 활용이 급부상하고 있으며, 강우가 유입되는 지하유입구에 대한 수리학적 검토를 통한 성능 분석이 중요하다. 본 연구에서는 지하 유입구로 활용되고 있는 접선식(tangential) 유입구와 나선식(spiral) 유입구에 대해 유입유량 변화에 따른 유입부 수위를 계측하고 흐름 특성 변화를 분석했다. 나선식 유입구의 경우, 저유량 조건에서의 와류 유도 효과를 개선하기 위해 유입부 바닥면에 계단형 다단식 구조를 도입했다. 접선식 유입구에서는 고유량 유입조건 아래 도수(hydraulic jump)가 발생하며 유량 배제 효과가 급격하게 감소했다. 다단식 나선(multi-stage) 유입구의 경우, 접선식 유입구보다 유입유량 증가에 따른 수위 상승률은 높지만 저유량 및 고유량 유입조건에 대해 안정적인 유량 배제 효과를 유지했다. 또한, 실험에서 사용된 유입구 모형이 활용될 수 있도록 접선식 유입구와 다단식 나선 유입구 모형에 대한 수위-유량 관계 실험식(empirical formula)을 제시했다.

Keywords

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Fig. 1. Tangential inlet

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Fig. 2. Spiral inlet

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Fig. 3. Multi-stage spiral inlet

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Fig. 4. Experiment channel

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Fig. 5. Tangential inlet model

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Fig. 6. Multi-stage spiral inlet model

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Fig. 7. Measuring points of the water level

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Fig. 8. Water level with the inflow discharge of the tangential inlet

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Fig. 9. Water level with the inflow discharge of the multi-stage spiral inlet

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Fig. 10. Relationship between Froude number (Fr) and water levelratio (h/D)

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Fig. 11. Rising ratio of the water level with the inflow discharge

Table 1. Inflow conditions

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