Effect of Operational Pressure on Periodic Oscillation of Secondary Circulation near the Bottom of the Thermal Diffusion Column

Abstract

A computational code has been developed to analyze the non-steady flow field of the thermal diffusion column in the higher pressure region. Numerical analyses for H₂-HT are performed for the thermal diffusion column with an effective height of 1,500 mm, a hot wire of 0.15 mm and a cold wall of 15 mm in radius. In the condition that temperatures of cold wall and hot wire are 77.35 and 1,277.35 K at the pressure less than 0.112 MPa, the flow fields reach the steady state. However, a secondary circulation observed near the bottom of the column moves periodically at the pressure of 0.112 MPa or more. The frequency of the flow fields becomes larger as the gas pressure increases. The marginal pressure to make flow field apart from the steady state to the periodic state is predicted with the present analyses.

KEYWORDS:

• computer codes
• thermal diffusion column
• free convection
• secondary circulation
• pressure dependence
• flow vector
• temperature distribution
• radial velocity
• frequency
• periodic motion
• steady oscillation
• temperature dependence