Characteristics of turbulent velocity and temperature in a wall channel of a heated rod bundle

Turbulent air flow in a wall subchannel of a heated 37-rod bundle (P/D = 1.12, W/D = 1.06) was investigated. Measurements were performed with a hot-wire probe with x-wires and a temperature wire. The mean velocity, mean fluid temperature, wall shear stress and wall temperature, turbulent quantities such as the turbulent kinetic energy, Reynolds stresses, and turbulent heat fluxes were measured and are discussed with respect to data from isothermal flow in a wall channel and heated flow in a central channel of the same rod bundle. Also, data on the power spectral densities of the velocity and temperature fluctuations are presented. These data show the existence of large-scale periodic fluctuations of velocity and temperature in the gap region between two adjacent rods or between rods and the wall. These fluctuations are responsible for the high intersubchannel heat and momentum exchange.