Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Mechanical Engineering

Committee Chair

Qingyan Chen

Committee Member 1

Chao-Hsin Lin

Committee Member 2

Jun Chen

Committee Member 3

Panagiota Karava


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. This study aims to model the air distribution and contaminant transport in commercial aircraft cabins with gaspers on.

This study first conducted experimental measurements of airflow distribution in a mockup of half of a full-scale, one-row, single-aisle aircraft cabin with a gasper on. Particle image velocimetry (PIV) 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 (CFD) with the RNG k-ε model and the 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.

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 then 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 million 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 an MD82 airplane, the CFD simulation with the simplified gasper model was acceptable in predicting the distribution of air velocity, air temperature, and contaminant concentration.

Previous investigations have identified two turbulence models for cabin air with gaspers. To improve the accuracy of numerical simulation, this study first developed a hybrid turbulence model which was suitable for predicting the air distribution in an aircraft cabin with gaspers turned on. Next, the investigation validated the model using two sets of experimental data from a cabin mockup and an actual airplane. This study then used the validated model to systematically investigate the impact of gaspers on cabin air quality in a seven-row section of the fully-occupied, economy-class cabin of Boeing 767 and 737 airplanes. 210 CFD calculations formed a database consisting of 9450 data points that provide information about SARS infection risk. It was found that the distribution of opened gaspers can influence the infection risk for passengers. Even though the gasper supplies clean air, it is possible for it to have a negative impact on the passengers’ health. Statistically speaking, the overall effect of turning on the gaspers on the mean infection risk for the general population was neutral.

In airliner cabins, mixing ventilation systems with gaspers are not efficient in controlling contaminant transport. To improve the cabin environment, this investigation proposed an innovative ventilation system that would reduce contaminant transport while maintaining thermal comfort. We manufactured and installed the proposed ventilation system in an occupied seven-row, single-aisle aircraft cabin mockup. Air velocity, air temperature, and contaminant distribution in the cabin mockup were obtained by experimental measurements. The investigation used the experimental data to validate the results of CFD simulation. The validated CFD program was then used to study the impact of the locations and number of exhausts on contaminant removal and thermal comfort in a one-row section of a fully occupied Boeing-737 cabin. Although the diffusers in the proposed system were close to the passengers’ legs, the air velocity magnitude was acceptable in the lower part of the cabin and the leg area. The proposed system provided an acceptable thermal environment in the cabin, although passengers could feel cold when placing their legs directly in front of the diffusers. The four-exhaust configuration of the new ventilation system was the best, and it decreased the average exposure in the cabin by 57% and 53%, respectively, when compared with the mixing and displacement ventilation systems.

An innovative personalized displacement ventilation system which supplies air from individual displacement ventilation diffusers under the seat could possibly reduce the contaminant transport while maintaining thermal comfort in aircraft cabins. To evaluate the performance of the new ventilation system, this study first used Wells-Riley integrated CFD to obtain the SARS quanta based on a SARS outbreak on a flight. This investigation then compared the new ventilation system with mixing ventilation system and displacement ventilation system in a seven-row section of the fully occupied, economy-class cabin of Boeing 737 and Boeing 767 airplanes. It was found that the new system could reduce the passengers’ infection risk compared with the mixing ventilation system. The performance of the system was related to the source location when compared with the displacement ventilation system. Generally speaking, the new ventilation system had similar overall performance with the displacement ventilation system, and could better control contaminant transport compared with the mixing ventilation system. The innovative ventilation system performed the best in maintaining cabin thermal comfort.