A trajectory model was developed based on the ratio of the two momentums of a cough jet and a downward jet and was validated using the experimental data. Using the ratio of the two momentums, it may be estimated whether the transmission of a cough jet can be controlled. The results show that when the two momentums are equivalent or if the downward plane jet has a greater momentum, the cough jet is deflected downward and does not reach the breathing zone of the target thermal dummy. In this study, momentum comparison of the cough jet and the downward plane jet shows that the value of personal exposure to coughed particles depends on the ratio of jet momentums. A downward plane jet with a discharge velocity of 8.5Â m/sec can bend the cough jet to a certain extent. The results show that a relatively high-speed cough can easily penetrate a downward plane jet with a discharge velocity of less than 6Â m/sec. Chamber measurements were conducted to examine the interaction between a transient cough jet (discharge velocities of 12Â m/sec and 16Â m/sec) and a steady downward plane jet (discharge velocities from 1.0-8.5Â m/sec) with respect to the transport of and human exposure to coughed particles. To reduce the interpersonal transmission of coughed particles, the objective of this study was to analytically and experimentally investigate the performance of downward plane jets with various discharge velocities. In the wall jet region, observations reveal that the jet behaves like a typical three-dimensional wall jet and its axial velocity profiles show good agreement with the classical wall jet similarity function.ĭynamic interaction of a downward plane jet and a cough jet with respect to particle transmission: An analytical and experimental study.Ĭao, Guangyu Liu, Shichao Boor, Brandon E Novoselac, AtilaĪ cough jet can travel beyond the breathing zone of the source person, and thus, infectious viral- and bacterial-laden particles can be transported from the source person to others in close proximity. In the impingement region, the measured transverse flow fields provide new insights on the lateral motions induced by the impingement of the swirling jet. The development of the mean flow and turbulence characteristics associated with varying clearance heights are compared to illustrate boundary effects in these regions.
The study shows that the extent of each region varies under different clearance heights.
As a result, in contrast to its unconfined counterpart, the confined propeller jet features three regions, namely the free jet, impingement and wall jet regions. Similar to a confined offset jet, the propeller jet also exhibits a wall attachment behavior when it is placed near a plane boundary. Both the streamwise and transverse flow fields were measured to obtain the three-dimensional characteristics of the propeller jet. In each case, the mean flow properties and turbulence characteristics were measured in a larger field of view than those used in past studies. Three clearance heights, Z b = 2 D p, D p, and 0.5 D p, where D p = propeller diameter, were used to examine boundary effects on the development of the jet. The flow properties of a propeller jet in the presence of a plane bed boundary were investigated using the particle image velocimetry technique. Wei, Maoxing Chiew, Yee-Meng Hsieh, Shih-Chun Plane boundary effects on characteristics of propeller jets
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