Human respiration can act as contaminant source, while few studies were found in literature on the exhaled flow characteristic. For the exhaled flow is periodic and transient, the mean velocity is obtained by phase-averaged not time-averaged. In the paper, the PIV technique is used to study the exhaled flow characteristics. Experiment is carried on isothermal and non-isothermal conditions. The experiment indicated Compared with isothermal condition, the exhaled flow is upwards somewhat in the early stage, and most of the jet keeps horizontal. What is more, the jet region is larger in the non-isothermal conditions. Some turbulent characteristics are also obtained in the non-isothermal condition. The exhaled flow is highly turbulent. In a period, the turbulent intensity is relatively low in the early stage, while it is high in the middle and end stage. The vorticity of exhaled flow is quite large, and the value experiences a change along with the phase change. The vorticity shows unsymmetrical with the centerline somewhat.
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