The Experts below are selected from a list of 12 Experts worldwide ranked by ideXlab platform
Yang Liu - One of the best experts on this subject based on the ideXlab platform.
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A modified turbulence model for simulating Airflow Aircraft cabin environment with mixed convection.
Building simulation, 2020Co-Authors: Yijia Zhao, Zhengxian Liu, Ming Zhao, Yang LiuAbstract:The forced convection (Air Supply jet) and the natural convection (thermal plume of passenger) co-exist in an Aircraft cabin simultaneously. Due to the notable difference of the Reynolds numbers for the two convection processes, the traditional RANS method can hardly simulate the forced/natural convection flows accurately at the same time. In addition, the large geometric ratio between the Main Air Supply inlet and the whole cabin leads to difficulties in grid generation for the cabin space. An efficient computational model based on the standard k-e model is established to solve these problems. The coefficients in the dissipative equation are modified to compensate the enlarged numerical dissipation caused by coarse grid; meanwhile, the piecewise-defined turbulent viscosity is introduced to combine the forced and natural convection. The modified model is validated by available experimental results in a Boeing 737-200 mock-up. Furthermore, the unsteady characteristic of the Aircraft cabin environment is obtained and analyzed. According to the frequency analysis, it turns out that the thermal plume is the Main factor of the unsteady fluctuation in cabin.
Yijia Zhao - One of the best experts on this subject based on the ideXlab platform.
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A modified turbulence model for simulating Airflow Aircraft cabin environment with mixed convection.
Building simulation, 2020Co-Authors: Yijia Zhao, Zhengxian Liu, Ming Zhao, Yang LiuAbstract:The forced convection (Air Supply jet) and the natural convection (thermal plume of passenger) co-exist in an Aircraft cabin simultaneously. Due to the notable difference of the Reynolds numbers for the two convection processes, the traditional RANS method can hardly simulate the forced/natural convection flows accurately at the same time. In addition, the large geometric ratio between the Main Air Supply inlet and the whole cabin leads to difficulties in grid generation for the cabin space. An efficient computational model based on the standard k-e model is established to solve these problems. The coefficients in the dissipative equation are modified to compensate the enlarged numerical dissipation caused by coarse grid; meanwhile, the piecewise-defined turbulent viscosity is introduced to combine the forced and natural convection. The modified model is validated by available experimental results in a Boeing 737-200 mock-up. Furthermore, the unsteady characteristic of the Aircraft cabin environment is obtained and analyzed. According to the frequency analysis, it turns out that the thermal plume is the Main factor of the unsteady fluctuation in cabin.
Zhengxian Liu - One of the best experts on this subject based on the ideXlab platform.
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A modified turbulence model for simulating Airflow Aircraft cabin environment with mixed convection.
Building simulation, 2020Co-Authors: Yijia Zhao, Zhengxian Liu, Ming Zhao, Yang LiuAbstract:The forced convection (Air Supply jet) and the natural convection (thermal plume of passenger) co-exist in an Aircraft cabin simultaneously. Due to the notable difference of the Reynolds numbers for the two convection processes, the traditional RANS method can hardly simulate the forced/natural convection flows accurately at the same time. In addition, the large geometric ratio between the Main Air Supply inlet and the whole cabin leads to difficulties in grid generation for the cabin space. An efficient computational model based on the standard k-e model is established to solve these problems. The coefficients in the dissipative equation are modified to compensate the enlarged numerical dissipation caused by coarse grid; meanwhile, the piecewise-defined turbulent viscosity is introduced to combine the forced and natural convection. The modified model is validated by available experimental results in a Boeing 737-200 mock-up. Furthermore, the unsteady characteristic of the Aircraft cabin environment is obtained and analyzed. According to the frequency analysis, it turns out that the thermal plume is the Main factor of the unsteady fluctuation in cabin.
Ming Zhao - One of the best experts on this subject based on the ideXlab platform.
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A modified turbulence model for simulating Airflow Aircraft cabin environment with mixed convection.
Building simulation, 2020Co-Authors: Yijia Zhao, Zhengxian Liu, Ming Zhao, Yang LiuAbstract:The forced convection (Air Supply jet) and the natural convection (thermal plume of passenger) co-exist in an Aircraft cabin simultaneously. Due to the notable difference of the Reynolds numbers for the two convection processes, the traditional RANS method can hardly simulate the forced/natural convection flows accurately at the same time. In addition, the large geometric ratio between the Main Air Supply inlet and the whole cabin leads to difficulties in grid generation for the cabin space. An efficient computational model based on the standard k-e model is established to solve these problems. The coefficients in the dissipative equation are modified to compensate the enlarged numerical dissipation caused by coarse grid; meanwhile, the piecewise-defined turbulent viscosity is introduced to combine the forced and natural convection. The modified model is validated by available experimental results in a Boeing 737-200 mock-up. Furthermore, the unsteady characteristic of the Aircraft cabin environment is obtained and analyzed. According to the frequency analysis, it turns out that the thermal plume is the Main factor of the unsteady fluctuation in cabin.
J. R. Tippetts - One of the best experts on this subject based on the ideXlab platform.
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The application of a variable-area jet pump to the external recirculation of hot flue-gases
Journal of The Institute of Energy, 1995Co-Authors: G. H. Priestman, J. R. TippettsAbstract:A jet pump of special design, having a variable-geometry nozzle, is applied to the external recirculation of flue gas in a furnace system. This new concept improves reliability by eliminating the need for a flue-gas fan, and enables the recycle of high-temperature gas to be effected. Recycle is induced by simply increasing the Main Air Supply pressure by a reasonably modest amount, while the nozzle area of the jet pump is reduced by the progressive insertion of a co-axial spear. Details are given of the jet pump design. A model of its operating characteristics is given, which modifies standard incompressible-flow jet-pump theory such that it can be applied to the large nozzle : mixing-tube area ratio designs required for this application. The model is used to predict the jet pump's operating characteristics and the potential performance envelope of a flue-gas recirculation system. It is demonstrated that the amount of hot flue gas that can be recycled rises with available Air-Supply pressure but varies inversely with the recycle gas temperature. Results are given for experiments conducted with two jet pumps, including the use of hot Air and helium to obtain data at various density ratios. The results agree well with the proposed model, and confirm the proposed operatiqn of the flue-gas recycle system.
