Measurements of the flow and thermal characteristics of turbulent jets in cross flow

Sherif, Sherif
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Mechanical Engineering
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Mechanical Engineering

An experimental investigation of the flow, turbulence, and thermal characteristics of heated, cooled, and isothermal turbulent jets in cross flow is reported. The experiments were carried out in a water channel facility of the recirculation type. Hot or cold water was injected verically upward from a circular pipe located near the channel bottom to the cross-flowing stream in the channel. Hot- and cold-film anemometers along with appropriate linearizers, bridges, filters, and probes were used. A new signal analysis method was developed for resolving the complex three-dimensional structure of the mean turbulent flow field resulting from the interaction between the free stream and the jet. A rotatable probe technique was used to measure the size components of the Reynolds stress tensor in isothermal flows of any turbulence intensity. New expressions that correct for the temperature contamination of the velocity signals in nonisothermal flows were developed for both the linearized and unlinearized anemometer responses;Mean velocity and turbulence intensity data were obtained for the isothermal jet at jet-to-free stream velocity ratios of 2, 4, and 6 both in and outside the jet plane of symmetry. For the latter velocity ratio, a detailed analysis was carried out to reveal the details of the three-dimensional structure of the flow field. A similar analysis was made for the heated jet at a velocity ratio of 4. For this latter velocity ratio, the turbulent shear stresses, the turbulent RMS velocity fluctuations, the structural parameter, correlation coefficients, and the turbulent kinetic energy were obtained for the isothermal jet. Mean and RMS temperatures, on the other hand, were obtained for both heated and cooled jets. In the former case, velocity ratios of 1, 2, 4, and 7 were studied with a jet discharge temperature approximately 50(DEGREES)F to 75(DEGREES)F higher than the free stream temperature. In the latter case, velocity ratios of 1, 4, and 7 were employed with temperature differences of approximately -20(DEGREES)F and -50(DEGREES)F;The measurements reported in this study provide new information on the velocity, turbulence, and thermal field of turbulent jets in cross flow. These data should be useful for the development, improvement, and verification of better prediction methods and turbulence models for complex free shear flows.