CFD를 이용한 플록큐레이터 회전방향에 따른 플록형성지 유동 평가

조영만(Young Man Cho),유수전(Soo Jeon Yoo),노재순(Jae Soon Roh),김택준(Taek Jun Kim),김창원(Chang Won Kim) 大韓環境工學會 2009 대한환경공학회지 Vol.31 No.5

정수처리공정에서 안정적인 탁도 관리가 날이 갈수록 중요해지고 있다. 따라서 침전 효율 향상을 위한 플록형성 공정의 최적화는 매우 중요하다. 우리는 전산유체역학적 방법을 이용하여 플록큐레이터의 회전방향(시계방향, 반시계방향)에 따른 플록형성지 내 유동특성을 평가하였다. 평가 결과, 플록큐레이터가 시계방향으로 회전하는 경우는 플록큐레이터 회전방향과 수류 흐름이 일치하는 수표면 쪽에서 유동이 강해지고 유출량의 분산 및 표준편차는 각각 8.5, 2.9로 나타났다. 반면에 플록큐레이터가 반시계방향으로 회전하는 경우는 플록큐레이터 회전방향과 수류 흐름이 일치하는 바닥 쪽에서 유동이 강해지고 유출량의 분산 및 표준편차는 각각 5.3, 2.3으로 나타났다. 또한 플록형성지 유출량은 1,2단 플록큐레이터 회전방향보다는 3단 플록큐레이터의 회전방향에 의해 주로 영향을 받으며 3단 플록큐레이터가 반시계방향으로 회전하는 경우가 시계방향으로 회전하는 경우보다 유출량의 편차가 적기 때문에 침전지의 균등한 흐름을 위해 유리하다. With time, the stable management of turbidity is becoming more important in the water treatment process. So optimization of flocculation is important for the improvement of the sedimentation efficiency. we evaluated the hydrodynamic behavior in the rotation direction (clock-wise, counterclock-wise) of the flocculator in the flocculation basin using Computational Fluid Dynamics (CFD). The results of the CFD simulation, in cases where flocculators rotate in a clockwise direction, a stronger flow is formed near the surface of the water where the rotating direction and current of flow correspond. The variance and standard deviation of the flux are about 8.5 and 2.9 respectively. In contrast, in the case of a counterclockwise direction, a stronger flow is formed near the bottom of the basin. The variance and standard deviation of the flux are about 5.3 and 2.3, respectively. The effluent flux is affected more by the third flocculator spin than the first and second flocculator spins. The third flocculator spinning in the counterclockwise direction is better for the uniform flow of the sedimentation basin than the third flocculator spinning in the clockwise direction.

수처리 공정에서 디지털트윈 요소기술과 추진방안

조영만 ( Cho Young-man ),정용준 ( Jung Yong-jun ) 한국물환경학회 2022 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2022 No.-

전산유체를 활용한 정수지 최적 도류벽 형태 및 경제적인 장폭비 산정

조영만(Young Man Cho),노재순(Jae Soon Roh),빈재훈(Jae Hoon Bin),김태균(Tae Kyun Kim),최영준(Young June Choi) 大韓環境工學會 2011 대한환경공학회지 Vol.33 No.6

현재 국내 정수지 도류벽은 형태와 장폭비에 대한 명확한 기준이 없고 장폭비가 너무 작아 소독능을 만족하지 못하거나 지나치게 큰 장폭비로 비경제적인 설계를 하는 등 많은 혼란을 겪고 있어 수리적으로 유리한 도류벽의 형태와 경제적인 장폭비를 결정하는 것이 시급한 실정이다. 본 연구는 다양한 도류벽의 형태와 장폭비에 대해 전산유체역학 기법을 활용하여 수리적으로 가장 유리한 도류벽의 형태를 제시하고 가장 경제적인 장폭비를 도출하였다. 연구결과, 정수지내 도류벽의 형태는 동일한 형태와 구조라 하더라도 수류의 방향전환 횟수가 적은 구조가 수리적으로 유리하다. 둘째, 최적 도류벽 형태는 좌우 우류식(model 2)이며 최악의 형태는 두 방향으로 분산되고 다시 모아지는 분산형(model 4) 형태이다. 좌우 우류식은 분산형보다 도류벽의 개수를 67% 정도 줄일 수 있다. 셋째, 좌우 우류식 도류벽인 경우 경제적인 장폭비는 30~50이며 50을 초과할 경우 공사비 대비 T10/T 값의 증가량이 미미하여 경제적이지 못하다. We need to make the standard of the best baffle shape and L/W ratio of clearwell due to insufficient disinfection in short L/W ratio and uneconomic design in long L/W ratio. The objectives of this research were to evaluate the best shape of baffle and economic L/W ratio in the all sorts of shape and size by using computational fluid dynamics. In the results of this research, the baffle with smaller number of turning flow is more beneficial for hydraulic efficiency. So, even if the same shape and structure, baffle should be designed as smaller number in turning flow. The best shape of baffle is ZigZag type (model 2) and the worst shape is Distributed types (model 4). The ZigZag type can reduce number of baffle about 67% than that of the Distributed types. In the ZigZag type, economic L/W ratio is 30~50. If L/W ratio exceed over 50, it is not economic because construction costs greatly increase and an increasing rate of T10/T is very small.

전산유체역학를 이용한 급속혼화공정 교반효과 및 유동 평가

조영만 ( Young Man Cho ),유수전 ( Soo Jeon Yoo ),유평종 ( Pyung Joung Yoo ),김대영 ( Dae Young Kim ),황보봉형 ( Bong Hyeong Hwangbo ) 대한상하수도학회 2009 상하수도학회지 Vol.23 No.6

이동식 정류장치를 이용한 횡류식 침전지 침전효율 개선 연구

조영만(Young Man Cho) 大韓環境工學會 2005 대한환경공학회지 Vol.27 No.7

전산유체역학(CFD)를 활용한 정수공정에서 유공관 설계

조영만(Young Man Cho),유수전(Soo Jeon Yoo),노재순(Jae Soon Roh),빈재훈(Jae Hoon Bin) 大韓環境工學會 2010 대한환경공학회지 Vol.32 No.9

정수공정에서 활용되고 있는 유공관의 일반적인 기능은 균등한 압력으로 일정한 유량을 유출시키는 것이다. 정수공정에서 유공관이 여러 공정에서 활용되고 있음에도 불구하고 유공관 설계에 대한 일반적인 설계인자가 없는 실정이며 따라서 본 연구에서는 전산유체역학적(Computational Fluid Dynamics) 기법을 활용하여 정수공정에 활용되고 있는 유공관 설계인자를 도출하고자 하였다. 유공관 유출량의 균등성은 유공관 표면적 대비 전체 유공단면적 합의 비가 작아질수록 향상되는 경향을 보인다. 즉 유공 면적비가 작아질수록 유출 균등성은 그에 비례하여 향상되며 또한 동일한 면적비에서 유공의 개수가 증가할수록 유출량 균등성은 향상된다. 특히 유공관의 직경에 해당하는 길이 당 2개의 유공(2/D)을 배치하는 경우가 균등성의 향상 폭이 가장 크며 또한 압력 강하 값이 가장 적어 수리학적으로 가장 유리한 유공 개수이다. 유공관 유입 유속이 작고(약 0.06 m/s), 유공관 길이가 길어질수록 유출량은 전단에서 후단으로 갈수록 감소하며 반대로 유공관 유입 유속이 크고 (3 m/s) 유공관이 길어지면 유출량은 후단으로 갈수록 증가하는 경향을 보인다. Role of the perforated pipe is to drain the water with equal pressure and velocity through the holes of perforated pipe. The perforated pipe is being used in many processes of water treatment system, however, the design parameter of perforated pipe is not standardized in korea. In this study, we have found the design parameter of perforated pipe in the water treatment system using the Computational Fluid Dynamics (CFD). The uniformity of outflow from the perforated pipe is directly affected according to area ratio (gross area of holes/surface area of the perforated pipe). In other words, the uniformity of outflow is improved as area ratio is smaller. Also, at the same area ratio, the uniformity of outflow is improved as number of holes is increase. Specially, in case of the two holes per length of pipe diameter (2/D) shows the most uniformity of outflow and the best hydraulic with the smaller pressure drop. When the inlet velocity of pipe is about 0.06m/sec, the flux of pipe has decreased as from front to backward. When the inlet velocity is 3 m/s, the flux of pipe has increased as from front to backward.

전산유체역학을 활용한 유공관 최적설계 및 맥동식침전지 수리평가

조영만 ( Young Man Cho ) 한국수처리학회 2013 한국수처리학회지 Vol.21 No.4

The pulsator clarifiers is very sensitive about the changing of the water quantity. So the most important part of pulsator clarifiers is the perforated pipe for to drain the raw water with equal pressure and velocity. First, we evaluated the design parameters of the common perforated pipe. The uniformity of outflow from the perforated pipe is directly affected according to area ratio. In other words, the uniformity of outflow is improved as area ratio is smaller. Also, at the same area ratio, the uniformity of outflow is improved as number of holes is increase. Specially, in case of the two holes per length of pipe diameter(2/D) shows the most uniformity of outflow and the best hydraulic with the smaller pressure drop. Second, we evaluated the pulsator clarifiers that has installed and operated in H water treatment plant. Results, it was designed properly that the ratio of cross section between pipe and holes is 8.9%. But the distance of each holes should be improved to 2/D of the optimal value from 1.3/D. The standard deviation of distributed quantity from the middle channel to the hole pipe was 0.12 and from the hole pipe to holes was 0.04.

전산유체역학을 활용한 응집지 분배수로 최적설계

조영만 ( Young Man Cho ) 한국수처리학회 2013 한국수처리학회지 Vol.21 No.4

Uniform distribution at the channel and pipe is an important factor affecting not only floc formation of flocculation basin but also precipitation efficiency of sedimentation basin. There are a variety of design factors at the distribution channel such as the open channel type, pressure pipe type, velocity of channel inside, structure of inlet, outlet size, etc. we evaluated most suitable design method of the distribution channel of the flocculation basin by using computational fluid dynamics in this research. First, the uniformity of distribution is improved when the ratio of channel inlet and outlet Cross-sectional area small. If, however, the ratio of Cross-sectional area is become small, pressure in the channel rises. So the basis of the uniformity and pressure in channel, the suitable ratio of Cross-sectional area is about 5%~10%. Second, in the uniformity of distribution, the pressure pipe type is excellent than the open channel type. Third, the suitable inlet velocity of water is about o.5m/sec if consider the prevent sedimentation of SS and the rise of pipe pressure. Fourth, we can improve the stability of water flow by increasing the length of the inlet section, therefore proper inlet length is about 5m.

부산시 감조하천 동천의 수리 특성

조영만 ( Young Man Cho ),류동춘 ( Dong Choon Ryu ),유평종 ( Pyeong Jong Yoo ),최민식 ( Min Sik Choi ),설승수 ( Seung Su Seol ),김상현 ( Sang Hyun Kim ),이종진 ( Jong Jin Lee ) 한국수처리학회 2016 한국수처리학회지 Vol.24 No.2

Even though various management practices such as sediment dredging were attempted to improve water quality of Dongcheon located in Busan, the environmental condition of this stream was deteriorated. Therefore, Busan metropolitan city had pumped and diverted sea water to upstream of Dongcheon for several years. This study explored hydraulic characteristics of Dongcheon to configure the best management practice for ecological restoration and water quality improvement of a man made urban stream. Intensive field investigation indicates that average flow velocities at depths of 20% and 80% from the water surface ranged 5 to 10 cm/s and 2 to 5 cm/s, respectively. Concentrations of dissolved oxygen for all depths were less than 0.25 mg/l during low tidal period. Even though density difference can be found along stream depth, density current seems rarely generated in Dongcheon. Short period of high tidal portion and shallow depths are responsible for well mixing nature of Doncheon.

염소가스 누출사고 예방을 위한 염소저장시설 최적설계 방안

조영만 ( Young Man Cho ) 한국수처리학회 2013 한국수처리학회지 Vol.21 No.5

Chlorine is used in the pre-chlorination and post-chlorination that is a yellow-green gas under standard conditions, where it forms diatomic molecules. Elemental chlorine at high concentrations is extremely dangerous and poisonous for all living organisms, and was historically used in World War I as the first gaseous chemical warfare agent. Chlorine gas is a pulmonary irritant with intermediate water solubility that causes acute damage in the upper and lower respiratory tract. Despite the dangers of chlorine gas, the review of research of the safety-related chlorine facilities in water treatment plant is insufficient. In this study, in the case of the accident outbreak of chlorine gas we evaluated the overall safety in order to provide an optimal design method of the chlorine storage room. First, the gate of chlorine storage facilities should be designed the double doors of iron gate and shutter gate. It is the best secure. Second, in the shutter gate, to block the leaking chlorine gas through the door gap, it is desirable that the injection device of sodium hydroxide is designed. Third, the design of the discharge pressure of the chlorine gas should consider the storage facility size and discharge time. Fourth, at the same pressure, the more number of discharge inlet is more effective for chlorine gas emissions.