Strategy Of Mesh Choice In Numerical Simulation In Predicting Air Distribution In An Aircraft Cabin

Air distribution in airliner cabins is important for the thermal comfort and well-being of travelers and crew members. However, many recent studies found that thermal comfort in airliner cabins was not satisfactory. The spatial air temperature distributions in airliner cabins were not uniform, and many passengers found that their upper bodies were too warm and lower bodies too cold. Measurements in a large number of commercial airliner cabins identified many pollutants that are potentially harmful to passengers and crew members and should therefore be removed effectively from the cabins by ventilation. Adjustment of air distribution in cabins in order to improve thermal comfort and reduce pollutant levels is an important subject for airplane cabin designers and researchers.Experimental measurements and computer simulations are two of the primary methods of investigating air distribution in an airliner cabin. While experimental measurements in an airliner cabin were reliable, it was difficult to conduct the measurements on board with sufficient fine spatial resolution because of regulations imposed by aviation authorities and the high costs associated with the experime nts. Most of the measurements were conducted on the ground in airplanes or cabin mock-ups. CFD simulation, on the other hand, is less expensive and more efficient. Thus, recent studies of thermal comfort and air quality in airliner cabins have been conducted primarily by CFD. Because the geometry of an airliner cabin is very complex and the airflow appears unstable, the experience obtained in simulating airflow in other enclosed spaces, such as buildings, cannot be applied to airliner cabins. Therefore, it is important to investigate the use of CFD for this application. Because the mesh type and number used in CFD can play a significant role in the numerical results, this investigation conducted a systematic evaluation of mesh type and number. The goal was to identify a suitable mesh type and number for studying air distribution in an airliner cabin in order to improve the thermal comfort and wel-being of passengers and crew members.This investigation compared the results of steady RNG k-? model and unsteady RNG k-? model, and then evaluated the impact of three mesh types(hexahedral, tetrahedral, and hybrid cells) and five grid numbers(3, 6, 12, 24, and >38 million cells) on the accuracy and computing costs of air distribution simulations in a first-class cabin. This study performed numerical error analysis and compared the computed distributions of air velocity and temperature that resulted from different combinations of mesh type and number. Because the thermal plumes can be intermittent and give rise to time-dependent fluctuated flow fields around human bodies and the flow in the cabin was unstable. This investigation used unsteady RN G k-? model to study the impact of grid type and number on the prediction of air distributions in the airliner cabin. The study found that hexahedral meshes were the most accurate, but the computing costs were also the highest. A mesh with 12 million cells would produce acceptable numerical results for the first-class cabin, and a finer mesh with 59 million cells would not necessarily be better. Different mesh types would require different grid numbers in order to generate accurate results.