Dataset Information

A modified turbulence model for simulating airflow aircraft cabin environment with mixed convection.

ABSTRACT: 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.

Electronic supplementary material esm

Supplementary material is available in the online version of this article at 10.1007/s12273-020-0609-2.

SUBMITTER: Zhao Y

PROVIDER: S-EPMC7100490 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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A modified turbulence model for simulating airflow aircraft cabin environment with mixed convection.

Zhao Yijia Y Liu Zhengxian Z Li Xiaojian X Zhao Ming M Liu Yang Y

Building simulation 20200326 3

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 ...[more]

PMID: 32226591

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Project description:Pharmaceutical aerosol systems present a significant challenge to computational fluid dynamics (CFD) modeling based on the need to capture multiple levels of turbulence, frequent transition between laminar and turbulent flows, anisotropic turbulent particle dispersion, and near-wall particle transport phenomena often within geometrically complex systems over multiple time scales. Two-equation turbulence models, such as the k-ω family of approximations, offer a computationally efficient solution approach, but are known to require the use of near-wall (NW) corrections and eddy interaction model (EIM) modifications for accurate predictions of aerosol deposition. The objective of this study was to develop an efficient and effective two-equation turbulence modeling approach that enables accurate predictions of pharmaceutical aerosol deposition across a range of turbulence levels. Key systems considered were the traditional aerosol deposition benchmark cases of a 90-degree bend (Re=6,000) and a vertical straight section of pipe (Re=10,000), as well as a highly complex case of direct-to-infant (D2I) nose-to-lung pharmaceutical aerosol delivery from an air-jet dry powder inhaler (DPI) including a patient interface and infant nasal geometry through mid-trachea (500<Re<7,000). Of the k-ω family of models, the low Reynolds number (LRN) shear stress transport (SST) approach was determined to provide the best agreement with experimental aerosol deposition data in the D2I system, based on an improved simulation of turbulent jet flow that frequently occurs in DPIs. Considering NW corrections, a new correlation was developed to quantitatively predict best regional values of the y+limit, within which anisotropic NW turbulence is approximated. Considering EIM modifications, a previously described drift correction approach was implemented in pharmaceutical aerosol simulations for the first time. Considering all model corrections and modifications applied to the D2I system, regional relative errors in deposition fractions between CFD predictions and new experimental data were improved from 19-207% (no modifications) to 2-15% (all modifications) with a notable decrease in computational time (up to ∼15%). In conclusion, the highly efficient two-equation k-ω models with physically realistic corrections and modifications provided a viable, efficient and accurate approach to simulate the transport and deposition of pharmaceutical aerosols in complex airway systems that include laminar, turbulent and transitional flows.

Dataset Information

A modified turbulence model for simulating airflow aircraft cabin environment with mixed convection.

Electronic supplementary material esm

Publications

A modified turbulence model for simulating airflow aircraft cabin environment with mixed convection.

Similar Datasets

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