Daniel Wei

Experimental and numerical study of airflow distribution in an aircraft cabin mock-up with a gasper on

Overhead gaspers are prevalently installed in aircraft cabins as a personalized ventilation system. The air distribution in cabins with gaspers on is crucial for creating a thermally comfortable and healthy cabin environment. However, very few studies have investigated the suitable turbulence model to simulation air distribution in cabins with gaspers turned on. This study first conducted experimental measurements of airflow distribution in a mock-up of half of a full-scale, one-row, single-aisle aircraft cabin with a gasper on. Particle image velocimetry was used to measure the complex airflow field above a human simulator. This investigation then used the measured data to evaluate the performance of computational fluid dynamics with the re-normalization group (RNG) k–ε model and the shear stress transport (SST) k–ω model. The results showed that the SST k–ω model was more accurate than the RNG k–ε model for predicting the airflow distribution in gasper-induced jet dominant region in an aircraft cabin.

Routes of transmission of influenza A H1N1, SARS CoV, and norovirus in air cabin: Comparative analyses

Abstract Identifying the exact transmission route(s) of infectious diseases in indoor environments is a crucial step in developing effective intervention strategies. In this study, we proposed a comparative analysis approach and built a model to simulate outbreaks of 3 different in‐flight infections in a similar cabin environment, that is, influenza A H1N1, severe acute respiratory syndrome (SARS) coronavirus (CoV), and norovirus. The simulation results seemed to suggest that the close contact route was probably the most significant route (contributes 70%, 95% confidence interval [CI]: 67%‐72%) in the in‐flight transmission of influenza A H1N1 transmission; as a result, passengers within 2 rows of the index case had a significantly higher infection risk than others in the outbreak (relative risk [RR]: 13.4, 95% CI: 1.5‐121.2, P = .019). For SARS CoV, the airborne, close contact, and fomite routes contributed 21% (95% CI: 19%‐23%), 29% (95% CI: 27%‐31%), and 50% (95% CI: 48%‐53%), respectively. For norovirus, the simulation results suggested that the fomite route played the dominant role (contributes 85%, 95% CI: 83%‐87%) in most cases; as a result, passengers in aisle seats had a significantly higher infection risk than others (RR: 9.5, 95% CI: 1.2‐77.4, P = .022). This work highlighted a method for using observed outbreak data to analyze the roles of different infection transmission routes.

Logistic growth of a surface contamination network and its role in disease spread

Surfaces and objects surround us, and touching them is integral to everyday life. Pathogen contaminated surfaces (fomites) are known to transmit diseases. However, little is known about the ways and speed at which surfaces become contaminated. We found that under certain conditions, the number of contaminated surfaces grows logistically, corresponding to possible rapid transmission of infection. In such a surface network, pathogen can be transmitted great distances quickly—as far as people move. We found that the surface contamination network in aircraft cabins exhibits a community structure, with small communities connected by the aisle seatback surfaces and toilets, which are high-touch surfaces. In less than two to three hours, most high-touch surfaces in the cabin are contaminated, and within five to six hours nearly all touchable surfaces are contaminated. During short haul flight, aisle passengers have higher fomite exposure. This closely matches the spatial infection pattern of one reported inflight norovirus outbreaks. Our model is generally applicable to other crowded settings. The commonly repeated advice to “wash hands frequently” may be replaced in future by more strategic advice such as “clean surfaces right now”, or advice based on who should wash their hands, and when.

Predicting airflow distribution and contaminant transport in aircraft cabins with a simplified gasper model

This study investigated the air distribution and contaminant transport in aircraft cabins with gaspers by using computational fluid dynamics (CFD). If the detailed gasper geometry were used in the CFD simulations, the grid number would be unacceptably high. To reduce the grid number, this investigation proposed a method for simplifying the gasper geometry. The method was then validated by two sets of experimental data obtained from a cabin mockup and a real aircraft cabin. It was found that for the cabin mockup, the CFD simulation with the simplified gasper model reduced the grid number from 1.58 to 0.3 million and the computing cost from 2 days to 1 hour without compromising the accuracy. In the five-row economy-class cabin of the MD-82 airplane, the CFD simulation with the simplified gasper model was acceptable in predicting the distribution of air velocity, air temperature, and contaminant concentration.