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계범준(Beomjun Kye),박근태(Keuntae Park),최해천(Haecheon Choi),이명성(Myungsung Lee),김주한(Joo-Han Kim) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
In a centrifugal pump, due to its complicated geometry and flow phenomena, an accurate prediction of flow features is a challenging task. In the present study, large eddy simulation is performed to investigate the flow in a centrifugal pump including the impeller and the volute. A dynamic global model (Lee et al., 2010) is used for a subgrid-scale model, and an immersed boundary method is adopted in a non-inertial reference frame (Kim & Choi, 2006) to impose the no-slip boundary condition on stationary and rotating surfaces. The pump performances computed are in good agreements with those by experiments. The instantaneous flow fields indicate that recirculation zones are generated on the pressure and suction surfaces of impeller blades and near the volute tongue. Also, notable amounts of backflow and leakage flow are observed near the impeller outlet and the volute casing.
직교류 팬 내부 유동의 큰 에디 모사 해석과 형상 최적화 및 사인파형 돌출부를 활용한 유동제어
계범준(Beomjun Kye),윤원혁(Wonhyuck Yoon),박근태(Keuntae Park),김재림(Jaerim Kim),박종환(Jonghwan Park),장재희(Jaehee Chang),진도현(Dohyun Jin),최해천(Haecheon Choi),이명성(Myungsung Lee),김주한(Joo-Han Kim) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
The flow characteristics in a cross-flow fan is investigated using large eddy simulation with an immersed boundary method. The Reynolds number of the fan is Re = 5,400 based on the blade chord length and the blade tip velocity at its outer radius. Due to the rotation of fan, an eccentric vortex locates at the lower right corner near a stabilizer, and the main flow passes by this vortex. A recirculation region at the inlet of the rearguide and flow separation on blade suction surfaces are also captured in the simulation. To alleviate these losses and increase the fan efficiency, we modify the casing geometry and apply sinusoidal protrusions on the leading edge of each blade inspired by humpback whale’s tubercle. To find optimum period and amplitude of the protrusion, we adopt the response surface methodology. The modified casing and optimum sinusoidal protrusions on each blade reduce the recirculation zone near the inflow region and vortex shedding inside the fan. Experimental results show that the fan with the optimum sinusoidal protrusions improves the fan efficiency by 5.2%, which is in good agreement with the LES. The fan with both the modified casing and optimum protrusions on each blade demonstrates higher efficiencies at all flow rates.