Isothermal and heated turbulent upflow in a vertical annular channel – Part I. Experimental measurements

Abstract

The velocity and thermal fields were measured in isothermal and heated turbulent upflow of liquid Refrigerant-113 through a vertical annular channel of inner to outer radius ratio 0.415. A two-component laser Doppler velocimeter was used for the velocity measurements and, simultaneously, a cold-wire for the temperature measurements. The dimensions of the LDV measuring volume and the cold-wire, and their proximity to each other were important considerations. Also crucial to the measurements were the LDV coincidence time window and the temporal response of the cold-wire. Time-mean axial and radial velocities, axial and radial turbulent intensities, the single-point cross-correlation between axial and radial velocity fluctuations (∼axial Reynolds shear stress), and single-point cross-correlations between axial velocity and temperature fluctuations (∼axial turbulent heat flux) and radial velocity and temperature fluctuations (∼radial turbulent heat flux) were measured. Results are reported for Reynolds numbers at channel inlet of 22,800, 31,500, and 46,400 at annulus inner wall heat fluxes of 0, 9000 and 16,000 W m −2. The measured radial turbulent heat flux distribution is compared with that calculated from an approximate form of the thermal energy balance equation in which the measured mean velocity and temperature values are used. Also reported is the radial distribution of turbulent Prandtl number estimated from the measurements.