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박다인 ( Da-in Bak ),이상호 ( Sang-ho Lee ),이상설 ( Sang-seol Lee ) 한국환경기술학회 2021 한국환경기술학회지 Vol.22 No.1
Experimental analysis has been carried out to investigate the seawater flow fields and turbine output characteristics of vertical dual channels in a tidal current power generation system. The turbine outputs such as rotational speed and power generation of the dual channel blades are severely affected by the seawater flow field and the electrical load of the generator. Compact scale model by 3D printing method with the dual channel turbines were constructed in a water tank test device, and the rotational speed and power output of the turbines at the upper and lower channels were compared for various inlet flow velocities and electric loads. Axial flow velocity was decreased as it approached the entrance of the dual channel turbine system while the velocity for the upper channel was relatively lower than that for the lower channel. This results in relatively high rpm speed and power output of the turbine in the lower channel due to flow momentum and blade torque. The speed was also increased with the electrical load of the axially connected generator for less than 200Ω, and it was a little lower for upper channel. The generation efficiency gradually increased with the tip speed ratio, and then decreases after the peak while it depends on the inlet flow velocity. It is expected that these results can be used as applicable design data for the development of the multi-channel tidal power generation system.
박다인(Da In Bak),한석종(Seok Jong Han),이상호(Sang Ho Lee),권병민(Kwon Byung Min) 대한설비공학회 2019 대한설비공학회 학술발표대회논문집 Vol.2019 No.11
The wind tunnel is a ground test equipment, and it is a device that artificially allows air to flow to analyze the force of the air flow on the object or the movement of the object in the flow. The flow of air in the wind tunnel should be a uniform flow to achieve the same effect as the actual situation. In this study, the air flow of the test section in the wind tunnel system was analyzed by using the numerical analysis. The flow characteristics and velocity uniformity of four sections were compared from the nozzle outlet. As a result, the uniformity according to the screen spacing increased as the spacing decreased. The uniformity according to the number of screens was about 0.5% higher than that of four screens with one screen. The uniformity decreased as the measurement cross section location moved away from the nozzle outlet.
한석종(Seok Jong Han),박다인(Da In Bak),이상호(Sang Ho Lee),이재규(Jae Gyu Lee) 대한설비공학회 2019 대한설비공학회 학술발표대회논문집 Vol.2019 No.11
This study analyzed the heat transfer characteristics of the contact conditions change between the thickness and the material of the insulation in the floor assembly of the wind tunnel test section. Computational FEM technique was used to analyze the temperature distribution and heat flux characteristics for the floor assembly of the test section. As the thickness of the insulation increased, the heat flux at the floor assembly of the test section decreased by about 15%. At the same time, the thermal insulation performance varied greatly within the thermal contact conductance of 250 ~ 1,000 W/㎡K. The heat transfer characteristics of the floor assembly in the wind tunnel test section obtained through this study can provide basic data for the development of environmental test wind tunnels.