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

The velocity and thermal fields were measured in isothermal and heated turb ulent upflow of liquid Refrigerant-113 through a Vertical annular channel o f inner to outer radius ratio 0.415. A two-component laser Doppler velocime ter was used for the velocity measurements and, simultaneously, a cold-wire for the temperature measurements. The:dimensions of the LDV measuring volu me and the cold-wire, and their proximity to each other were important cons iderations. Also crucial to the measurements were the LDV coincidence time window and the temporal response of the cold-wire. Time-mean axial and radi al velocities, axial and radial turbulent intensities, the single-point cro ss-correlation between axial and radial velocity fluctuations (similar to a xial Reynolds shear stress), and single-point cross-correlations between ax ial velocity and temperature fluctuations (similar to axial turbulent heat flux) and radial velocity and temperature fluctuations (similar to radial t urbulent heat flux) were measured. Results are reported for Reynolds number s 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 f lux 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 o f turbulent Prandtl number estimated from the measurements. (C) 2001 Elsevi er Science Ltd. All rights reserved.