• Nuclear Engineering and Technology
• /
• v.53 no.12
• /
• pp.3918-3929
• /
• 2021

In this study, we experimentally investigate of a two-phase natural circulation loop that functions as a passive containment cooling system (PCCS). The experimental apparatus comprises two loops: a hot loop, for simulating containment under severe accidents, and a natural circulation loop, for simulating the PCCS. The experiment is conducted by controlling the pressure and inlet temperature of the hot loop in the range of 0.59-0.69 MPa (abs) and 119.6-158.8 ℃, respectively. The heat balance of the hot loop is established and compared with a natural circulation loop to assess the thermal reliability of the experimental apparatus, and an additional system is installed to measure the vapor mass flow rate. Furthermore, the thermal-hydraulic characteristics are considered in terms of a temperature, mass flow rate, heat transfer coefficient (HTC), etc. The flow rate of the natural circulation loop is induced primarily by flashing, and a distortion is observed in the local HTC because of the fully develop as well as subcooled boiling. As a result, we present the amount of heat capacity that the PCCS can passively remove according to the experimental conditions and compared the heat transfer performance using Chen's and Dittus-Boelter correlation.

• 한국전산유체공학회:학술대회논문집
• /
• 2004.10a
• /
• pp.95-99
• /
• 2004

The developing Smart UAV in KARI supposes high speed flight as like a conventional plane, as well as vertical takeoff and landing as like a helicopter. Therefore, the air intake system should be designed to provide the sufficient air flow to the engine and the maximum possible total pressure recovery at the engine intake screen over a wide range of flight conditions. For this purpose, we designed the intake system using a pilot type intake model and plenum chamber In this paper, we designed the intake model and analyzed the performance of designed intake system using the general-purpose commercial CFD code, CFD-ACE+ For 3-D calculation, we generated mesh using the unstructured gird and used $\kappa-\epsilon$ turbulence model. The analysis results of the total pressure variation and the velocity distribution was illustrated in this paper. The pressure recovery and distortion coefficient at a plane coincident with the compressor inlet were calculated and streamline variation through the intake system was investigated at the worst condition as well as the standard flight condition.