Fig. 1. Double-deck TBM tunnel example

Friction loss of multi-purpose stormwater tunnel simulated by Flow 3D

이두한1
, 김정환2
, 정건희2*
1한국건설기술연구원 수자원하천연구소, 2호서대학교 토목공학과

Abstract

본 최근 지구의 온난화로 인하여 극한 홍수가 자주 발생하고 있으며, 기존 도시 유역의 우수배제시설 용량부족 등으로 도시홍수가 빈번하게 발생하고 있으므로, 주요 범람지역의 홍수량을 우회하거나 저류하여 홍수를 방지하기 위한 수로터널의 개발이 요구된다.

본 연구에서는 교통기능과 수로기능을 동시에 갖춘 다기능 수로 터널의 설계 기준을 개발하기 위한 수리 실험 및 Flow3D를 이용한 수치모의을 수행하였다. 수치모의결과 동일한 수로 터널 구간 내 발생하는 마찰손실의 크기는 수치모의로 도출된 마찰손실이 이론적으로 계산한 마찰손실보다 더 크게 발생함을 관측하였으며, 이는 수로의 형상이 비원형인 경우에는 관의 기하학적 형상에 의한 흐름구조의 변화로 추가적인 마찰손실이 발생하는 것이 원인으로 판단된다.

마찰손실의 증가는 난류보다 층류에서 두드러졌다. 따라서 터널의 홍수량 흐름 시 마찰손실계수가 터널의 형상에 좌우되며, 실무에서 정확한 설계를 위해 방수로 터널의 형상을 주의 깊게 고려해야 한다는 결론을 내렸다. 이는 실제 방수로 터널 설계에 활용될 수 있는 기본 정보를 제공할 수 있을 것으로 보인다.

The extreme floods recently are have been attributed global warming, The development of a canal tunnel to prevent floods by making a bypass or undercurrent to flood discharge in a major flooding area is required because urban flooding in heavy rainfall occurs frequently, increasing the impermeability according to lack of capacity in sewage to urbanization by the existing urban basin. In this study, a numerical simulation was performed to support design standards for a multi-purpose waterway tunnel combined road tunnel of canal tunnel. The numerical simulation showed that the size of the friction loss occurring in the tunnel section of the same channel occurred more than the theoretically calculated frictional loss derived from the numerical simulations. This is probably due to the additional frictional loss caused by the change in the flow structure due to the geometry of the pipe when the shape of the channel is non-circular. The increase in friction loss was more pronounced in the laminar flow than in the turbulent flow. Depending on the shape of the conduit, the friction loss should be adjusted for accurate flow calculations. This result can provide the basin information about the design of flood by a pass conduit

Fig. 1. Double-deck TBM tunnel example
Fig. 1. Double-deck TBM tunnel example
Table 1. Discharge cases
Table 1. Discharge cases
Fig. 3. Setup of geometry
Fig. 3. Setup of geometry
Table 2. Boundary applied model
Table 2. Boundary applied model
Fig. 4. Pressure value according to the 6 different discharges
Fig. 4. Pressure value according to the 6 different discharges
Fig. 5. Hydraulic grade line along the stormwater tunnel using FLOW-3D
Fig. 5. Hydraulic grade line along the stormwater tunnel using FLOW-3D
Fig. 6. Head loss compared hydraulic experiment with Flow 3D and assumed circular pipe
Fig. 6. Head loss compared hydraulic experiment with Flow 3D and assumed circular pipe
Table 3. Measured and calculated frictional loss coefficient in the discharge cases
Table 3. Measured and calculated frictional loss coefficient in the discharge cases
Fig. 7. Comparison of frictional loss coefficient according to the Reynolds number
Fig. 7. Comparison of frictional loss coefficient according to the Reynolds number

References

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DOI: https://doi.org/10.1016/j.proeng.2017.02.354
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