This study aims to elucidate the scaling law to provide the critical condition on appearance of the downwash pattern of the hot smoke ejected from a chimney in a turbulent cross flow. A specially designed wind tunnel with an active turbulence generator developed by Makita was adopted to offer a quasi-isotropic turbulence field in a lab-scale test facility. A heated jet with smoke is issued into the cross flow from the vertically oriented chimney placed in the test section of the wind tunnel. In this study, the experimental parameters considered are temperature of the heated jet (smoke), jet ejected velocity, and cross-wind velocity, respectively. In the previous work, only two-patterns were observed under the condition studied in quasi-isotropic turbulence condition, such as meandering motion in downstream (Mode V) and downwash (Mode VI). The boundary of these two modes is found to be sensitive to all three parameters, suggesting that all are similarly important to determine the boundary. The observed data are summarized in the physical plane of Reynolds number and modified jet-Froude number, and it was found that all plots are collapsed into the single line. This result suggests that the viscous effect around the chimney plays a role on the appearance of downwash pattern of the hot smoke. It is necessary to check whether the scaling law would work even though the larger scale is imposed, whose Reynolds number based on the chimney scale is large enough and viscous force becomes less important.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.