High-Energy X-Ray CT Measurement of Void Fraction Distribution Around Part Length Rods in a Rod Bundle at High Pressure and Temperatures

A boiling experiment was conducted to acquire a three-dimensional void fraction distribution in a rod bundle with part length rods. The test section was a 5 × 5 heated rod bundle that partially simulated a BWR rod bundle, and three PLRs were arranged together in the corner. The heated length of the full-length rod was 3.71 m, which is equal in length to an actual fuel rod in BWRs, whereas the heated length of the PLR was 1.85 m. The rod bundle exhibited an axially and radially uniform heat flux. Further, the local void fraction was quantified by normalizing the intensities in the CT images of the boiling two-phase flow with those obtained under the liquid-phase and gas-phase conditions. The cross-sectional void fraction distribution was acquired at six height levels. The experimental results exhibited the void distribution around PLRs with respect to a wide range of flow conditions, inlet temperatures, inlet flow rates, bundle thermal powers, and system pressures.

Experimental Investigation on Influence of Inclination and Curved Surface of Ship Bottom in Air Lubrication Method

The air lubrication method, which mixes millimeter bubbles into the flow around the hull and reduces frictional resistance, is expected to have a large energy saving effect among a number of marine energy saving technologies. Concerning the frictional drag reduction effect using the air lubrication method, in this study, the frictional drag reduction effect was experimentally investigated for gas-liquid two phase flow considering the influence of inclination and curved surface of the ship bottom. Measurement of local shear stress and measurement of void fraction distribution near the wall surface were carried out and the correlation between local shear stress and local void fraction distribution was grasped.