Turbulent structure of isothermal and nonisothermal liquid metal pipe flow

Abstract

The structure of fully-developed mercury pipe flow, with and without heat transfer, was studied at a Reynolds number of 50000 using a hot-film anemometer. Traverses were made in a 1–434 in. dia, vertical, heated test section at a constant wall heat flux of 3820 Btu/hft 2. Axial turbulent velocity fluctuation measurements in isothermal pipe flow were made with both x-sensor und single-sensor hot-film probes. The radial turbulent velocity fluctuation intensity and the turbulent shear stress were also measured with an x-sensor probe. General agreement of the velocity results with corresponding measurements made in air indicates that the mercury flow turbulent velocity structure is similar to other fluids. The production and dissipation of turbulent kinetic energy were calculated from both single sensor and x-sensor data and were found to agree closely with the air data of Laufer. Turbulent temperature fluctuations, measured by using the hot-film anemometer as a resistance thermometer, were found to agree with the results of other measuring techniques. The turbulent axial heat flux, ρc puθ , and the turbulent radial heat flux, ρ c pu rθ , were also measured with both single and x-sensor hot-film probes using a modified Kovasznay method to separate temperature and velocity sensitivities. The combination of relatively poor velocity sensitivity combined with the large temperature sensitivity and superimposed axial free convection resulted in uncertain values of u xθ . The measured values of u rθ were unusually large in the wall region but indicated that convective and conductive transport were nearly equal in the turbulent core region.