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Hu X.,Tianjin University | Hu X.,Tianjin Key Laboratory of Indoor Air Environmental Quality Control | You X.-Y.,Tianjin University | You X.-Y.,Tianjin Key Laboratory of Indoor Air Environmental Quality Control
Building Simulation | Year: 2015

Comfortable and healthy aircraft cabin environment is required as more and more people choose to travel by air. The cabin environment is optimized by searching the optimal control parameters such as air supply velocity, angle and temperature. The optimal solutions are obtained by combining a multi-objective particle swarm optimization (MOPSO) with the simulation of computational fluid dynamics (CFD). It is found that different combinations of optimal air supply parameters can build an optimal cabin environment and the locations of the obtained optimal solutions are isolated in their value spaces. To achieve a stable engineering control operation, the determination of a stable range of optimal air supply parameters is required. Therefore, a method by using cluster analysis is developed to obtain stable ranges of optimal air supply parameters. Results show that the proposed method can obtain the ranges of optimal air supply parameters successfully. © 2015, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.


Feng L.,Tianjin Key Laboratory of Indoor Air Environmental Quality Control | Feng L.,Tianjin University | Yao S.,Tianjin University | Sun H.,Tianjin Key Laboratory of Indoor Air Environmental Quality Control | And 4 more authors.
Building and Environment | Year: 2015

Breathing is a high-risk behavior for spreading infectious diseases in enclosed environments, so it is important to investigate the characteristics of human exhalation flow and dispersal of exhaled air to reduce the risk. This paper used two-dimensional time-resolved particle image velocimetry (2D TR-PIV) to measure the exhaled flow from a breathing thermal manikin. Since the exhaled flow is transient and periodic, the phase-averaged method was used to analyze the flow characteristics. The results showed that the velocity profile of the flow exiting the mouth was bell-shaped for exhalation and flat for inhalation. The exhaled flow showed different characteristics during each stage of the exhalation process. In the initial phase, a mushroom-shaped flow arose, while some jet characteristics appeared in the middle phase. The effect of thermal buoyancy and thermal plume on the exhaled flow was analyzed. Clear turbulence characteristics were found in the exhaled flow, and the turbulence fluctuation was very strong in the transition stage between exhalation and inhalation. The last finding was that the distribution and value of vorticity were different in each phase. The results of quantitative PIV provided detailed information about the boundary condition set and validation data for CFD simulation. © 2015 Elsevier Ltd.


Dai S.,Tianjin Key Laboratory of Indoor Air Environmental Quality Control | Dai S.,Tianjin University | Sun H.,Tianjin Key Laboratory of Indoor Air Environmental Quality Control | Sun H.,Tianjin University | And 7 more authors.
Building and Environment | Year: 2015

Ventilation air distribution in commercial airliner cabins is crucial for creating a thermally comfortable and healthy cabin environment. The cabin air distribution is controlled by supply air diffusers and personal gaspers in nearly all aircrafts. Most previous studies focused on the flow field created by diffusers but ignored that created by gaspers. To study the characteristics of the jet flow from an aircraft gasper, fluid dynamic experiments were conducted on an actual gasper jet system in a simplified cabin mock-up. The gasper was taken from a retired MD82 airplane and its plenum was made in the full scale size of a real one. A high precision hot-wire anemometer was used to collect velocity magnitude and turbulence intensity data in the flow field of gasper isothermal jet. The evolution of velocity and turbulence intensity along the centreline of gasper jet under different airflow rates are analysed, results are then compared for three different opening sizes of gasper jet under the same airflow rate. Finally, a comparison between gasper jet and annular jet is presented to further discuss the experimental results. The results indicate that the flow field created by gasper is complicated near the nozzle but can be simplified when fully developed. A fitting empirical formula is developed to predict the velocity decay for gasper jet. This study also provides high quality experimental data for describing the flow field and for further validating CFD results for gasper jets. © 2015 Elsevier Ltd.

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