Commercial Aircraft Cabin Research Articles

An efficient strategy based on proper orthogonal decomposition for rapid determination of the location and rate of water vapor humidification in aircraft cabins

Currently, the air in commercial aircraft cabins during flights routinely exhibits extremely low relative humidity. But none of the previously published studies have addressed optimization of the humidification parameters in order to, create the desired humidity distributions in aircraft cabins at minimal cost. This study proposed an efficient strategy to accomplish the task. Under this strategy, a database of various potential humidification locations for aircraft cabins is first constructed. One scenario in the database is then selected by computational fluid dynamics (CFD)-based enumeration. Next, with the humidification location as prior information, the humidification rate and the air-supply temperature from the main ventilation system can be inversely designed by proper orthogonal decomposition. The above strategy was applied to a three-dimensional aircraft cabin model for the validated CFD cases. The results showed that an appropriate humidification for the cabin might both improve the thermal comfort of passengers and increase the humidity levels in the cabin; a decrease of the air-supply temperature from the main ventilation system would be beneficial in reducing the water vapor humidification rate required for passengers and allowing a higher humidification rate to be tolerated for the cabin walls. The parameters that improved the cabin air environment without significant moisture accumulation on walls were also provided by the proposed strategy. Compared with the full CFD simulation method, the proposed strategy is capable of providing accurate ranges of parameters while reducing the computing time by more than 95%, which demonstrates its competitive prospects.

Characterization of the 2.4- and 5-GHz Channels in a Single-Aisle Commercial Aircraft Cabin Using Ray Tracing

Characterization of the 2.4- and 5-GHz Channels in a Single-Aisle Commercial Aircraft Cabin Using Ray Tracing

Droplets Transmission Mechanism in a Commercial Wide-Body Aircraft Cabin

COVID-19 is a respiratory infectious disease that spreads readily between people, and an urgent issue of passengers’ exposure risk assessment in commercial aircraft has been raised because an aircraft cabin as a confined space may carry and transmit the disease worldwide. In this study, the droplets transmission process under different ventilation systems in a twin-aisle wide-body aircraft was studied using CFD simulations and the infection risk of passengers was assessed by the improved Wells–Riley model. Numerical results found that the transmission mechanism of droplets in the aircraft cabin was different depending on the type of ventilation systems and the location of the infectious source. Annular airflow could effectively enhance the ability of droplets transmission, while direct airflow, represented by displacement ventilation, could significantly inhibit droplets transmission. Accordingly, a new type of ventilation system was proposed based on the concept that the overall space is organized by annular airflow and the local area is direct airflow. Compared with sidewall mixing ventilation system, the infection risk of the new ventilation system presented in this study is reduced by 27%.

Integrated on-site collection and off-site analysis of airborne molecular contamination in cleanrooms for integrated circuit manufacturing processes

Both long-term on-site collection and off-site analysis methods were conducted to investigate airborne molecular contaminants (AMCs) in a semiconductor wafer cleanroom. The removal efficiency of SO2 and NO2 for chemical filters on a make-up air unit (MAU) in the cleanroom is approximately 50%, though this value does not meet the removal efficiency mentioned in the GB 36306 standard. The removal efficiencies of SO2, H2S, NO, NO2, NH3, and TVOC were approximately 76.5%, 50.9%, 83.5%, 99.3%, 94.8%, and 97.1% after the fan filter unit (FFU) was equipped with a chemical filter. AMCs mainly include benzene, toluene, ethylbenzene, xylene (BTEX), alkanes and alkenes, though BTEX accounts for 77% of the total. VOC concentrations in cleanrooms fitted with FFU chemical filters and where the process equipment was not in operation were found to be lower than those at domestic residences and slightly higher than those found in commercial aircraft cabin air. The daily average TVOC concentrations were negatively correlated with temperature (R2 = 0.46, p < 0.01) and positively correlated with humidity (R2 = 0.26, p < 0.01). The daily average NH3 concentrations were negatively correlated with T (R2 = 0.19, p < 0.05) and positively correlated with RH (R2 = 0.18, p < 0.01). Dibutyl phthalate (DBP) and dioctyl phthalate/diethylhexyl phthalate (DOP/DEHP) were detected in the new sealing joint strips in the HEPA filters. Phthalates and organophosphates were not detected in the new filter papers.

Numerical Simulation of the Novel Coronavirus Spread in Commercial Aircraft Cabin

Passengers carrying the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a commercial aircraft cabin may infect other passengers and the cabin crew. In this study, a cabin model of the seven-row Airbus A320 aircraft is constructed and meshed for simulating the SARS-CoV-2 spread in the cabin with a virus carrier using the Computational Fluid Dynamics (CFD) modeling tool. The passengers’ infection risk is also quantified with the susceptible exposure index (SEI) method. The results show that the virus spreads to the ceiling of the cabin within 50 s of the virus carrier’s normal breathing. Coughing makes the virus spread to the front three rows with a higher mass fraction. While the high mass fraction areas always stay on the same side of the aisle as the virus carrier, the adjacent passengers and the passengers in the back two rows are affected more than the others when the virus carrier breathes normally. Spread patterns under the carrier’s two breath conditions, normal breath and cough, were numerically simulated.

CONCEPTUAL DESIGN FOR ASSEMBLY IN AEROSPACE INDUSTRY: SENSITIVITY ANALYSIS OF MATHEMATICAL FRAMEWORK AND DESIGN PARAMETERS

AbstractOne of the most challenging activity in the engineering design process is the definition of a framework (model and parameters) for the characterization of specific processes such as installation and assembly. Aircraft system architectures are complex structures used to understand relation among elements (modules) inside an aircraft and its evaluation is one of the first activity since the conceptual design. The assessment of aircraft architectures, from the assembly perspective, requires parameter identification as well as the definition of the overall analysis framework (i.e., mathematical models, equations).The paper aims at the analysis of a mathematical framework (structure, equations and parameters) developed to assess the fit for assembly performances of aircraft system architectures by the mean of sensitivity analysis (One-Factor-At-Time method). The sensitivity analysis was performed on a complex engineering framework, i.e. the Conceptual Design for Assembly (CDfA) methodology, which is characterized by level, domains and attributes (parameters). A commercial aircraft cabin system was used as a case study to understand the use of different mathematical operators as well as the way to cluster attributes.

Antibiotic resistance and biofilm synthesis genes in airborne Staphylococcus in commercial aircraft cabins

Antibiotic resistance and biofilm synthesis genes in airborne Staphylococcus in commercial aircraft cabins

Experimental evaluation of particle exposure at different seats in a single-aisle aircraft cabin

During the COVID-19 pandemic, exposure to particles exhaled by infected passengers in commercial aircraft cabins has been a great concern. Currently, aircraft cabins adopt mixing ventilation. However, complete mixing may not be achieved, and thus the particle concentration in the respiratory zone may vary from seat to seat in a cabin. To evaluate the particle exposure in a typical single-aisle aircraft cabin, this investigation constructed an aircraft cabin mockup for experimental tests. Particles were released from a single source or dual sources at different seats to represent particles exhaled by infected passengers. The particle concentrations in the respiratory zones at various seats were measured and compared. The particle exposure was evaluated in both a cross section and a longitudinal section. Leaving the middle seat vacant to reduce particle exposure was also addressed. In addition, the velocity fields and air temperatures were measured to provide a better understanding of particle transport. It was found that the particle exposure at the window seat is always the lowest, regardless of the particle release locations. If the passenger seated in the middle does not release particles, his/her presence enhances the particle dispersion and thereby reduces the particle exposure for adjacent passengers. In the cabin mockup, the released particles can be transported across at least four rows of seats in the longitudinal direction.

Normal and extreme aircraft accelerations and the effects on exposure to expiratory airborne contaminant inside commercial aircraft cabins

A novel dataset based on satellite observations of aircraft positions was utilized to estimate normal accelerations of commercial aircraft during climb and descent legs. Further, these accelerations are used to simulate the effects on exposure to expiratory airborne contaminant inside commercial aircraft cabins. Compared to previous studies, which reported exposures more than twice due to high aircraft accelerations during the climb leg, the new findings suggest lower aircraft accelerations that result in exposures on par with steady level flights during climb and descent legs. The new findings place previous studies in context to be interpreted as extreme conditions only while they call for more detailed experimental investigations.

Temporal variations of ultrafine particle concentrations in aircraft cabin: A field study

Characterization of indoor aerosols in aircraft cabin has been of great interest. However, few studies have presented investigations of ultrafine particle (UFP) concentrations in actual aircraft cabin environment. In this study, we presented the characteristics of UFP number concentration levels, size distributions and temporal variations in fourteen randomly selected domestic commercial flights in China. The results showed that the concentration levels of UFPs in cabin air were 417 ± 1089 counts cm−3, with the lowest values occurred during cruising phase, and the dominant peak at the size channel of 72–100 nm in general. Some of the peak values were observed at the moments of turbulence of air stream or passing through cloud. To further identify contributions of UFPs from interior and outside cabin, CO2 in return air was simultaneously observed as a ventilation tracer to calculate the total airflow rates in those flights. A simplified model was developed to estimate the contribution rates of UFPs from bleed air and cabin interior at cruising phase in selected flights, combing with mass conservation equation under some assumptions. It indicated that, UFPs were commonly derived from unfiltered bleed air system in most of those flights at cruising phase. However, some exceptions were found in some flights, possibly due to unfiltered bleed air system and in-cabin ozonation. This study could be a reference for further understanding the status quo and control strategies of ultrafine particulate pollution in commercial aircraft cabins.

Generation of design alternatives of vertical passenger seat for standing cabin concept in commercial transport aircraft

Standing cabin concept, whereby the passengers are transported during flight in their standing position, has been proposed as one of the measures to make flying more affordable to the mass public. The vertical seat, or also known as standing seat, is an essential element for the implementation of this new cabin concept as it will determine the compliance to the governing aviation regulations and also the level of safety and comfort for the passengers. Up until now however, there is no vertical seat design that has been approved for use inside the commercial transport aircraft cabin. Therefore, this study presents the generation of alternative designs for the vertical seat through the use of systematic engineering design methodology with the use of supporting design tools such as Quality Function Deployment (QFD) chart and Morphological Matrix. Five alternative concepts of the vertical passenger seat design have been developed for further assessment study to select the best one among them.

Commercial aircraft cabin noise reduction based on SEA and transfer-matrix method

Commercial aircraft cabin noise reduction based on SEA and transfer-matrix method

The appropriate airflow rate for a nozzle in commercial aircraft cabins based on thermal comfort experiments

Personal air supply is important for both thermal comfort and air quality for individuals. However, no appropriate airflow rate for a nozzle in aircraft cabins is included in the existing standards. To study the effect of the nozzle air supply on thermal comfort and optimize the airflow rate for a nozzle, both measurements of the air flow field and a human thermal comfort survey were carried out in an experimental three-row aircraft cabin. The experiments used four airflow rates (0 L/s, 0.67 L/s, 0.96 L/s and 1.45 L/s) for a nozzle and three different cabin temperatures (24 °C, 26 °C, 28 °C). The air velocity distribution was obtained to calculate the air velocity for the nozzle jets at any point. This study provides an understanding of the effect of the nozzle air supply on passengers' thermal comfort and the optimal designs for a nozzle air supply system. The nozzle airflow rate for thermal comfort was calculated for a personal air supply at different cabin temperatures. The thermal comfort map for a nozzle can be referenced for the design of a personal air supply system in aircraft cabins.

Passenger thermal comfort and behavior: a field investigation in commercial aircraft cabins.

Passengers' behavioral adjustments warrant greater attention in thermal comfort research in aircraft cabins. Thus, a field investigation on 10 commercial aircrafts was conducted. Environment measurements were made and a questionnaire survey was performed. In the questionnaire, passengers were asked to evaluate their thermal comfort and record their adjustments regarding the usage of blankets and ventilation nozzles. The results indicate that behavioral adjustments in the cabin and the use of blankets or nozzle adjustments were employed by 2/3 of the passengers. However, the thermal comfort evaluations by these passengers were not as good as the evaluations by passengers who did not perform any adjustments. Possible causes such as differences in metabolic rate, clothing insulation and radiation asymmetry are discussed. The individual difference seems to be the most probable contributor, suggesting possibly that passengers who made adjustments had a narrower acceptance threshold or a higher expectancy regarding the cabin environment. Local thermal comfort was closely related to the adjustments and significantly influenced overall thermal comfort. Frequent flying was associated with lower ratings for the cabin environment.

Experimental studies of thermal environment and contaminant transport in a commercial aircraft cabin with gaspers on.

Gaspers installed in commercial airliner cabins are used to improve passengers' thermal comfort. To understand the impact of gasper airflow on the air quality in a cabin, this investigation measured the distributions of air velocity, air temperature, and gaseous contaminant concentration in five rows of the economy-class section of an MD-82 commercial aircraft. The gaseous contaminant was simulated using SF6 as a tracer gas with the source located at the mouth of a seated manikin close to the aisle. Two-fifths of the gaspers next to the aisle were turned on in the cabin, and each of them supplied air at a flow rate of 0.66l/s. The airflow rate in the economy-class cabin was controlled at 10l/s per passenger. Data obtained in a previous study of the cabin with all gaspers turned off were used for comparison. The results show that the jets from the gaspers had a substantial impact on the air velocity and contaminant transport in the cabin. The air velocity in the cabin was higher, and the air temperature slightly more uniform, when the gaspers were on than when they were off, but turning on the gaspers may not have improved the air quality.

Measurement of particle deposition rates in a commercial aircraft cabin

Thousands of people travel by air every day. In 2011, 730 million people traveled on commercial aircraft domestically (BTS 2012). These passengers are confined to a very high-occupant density space for extended periods of time, sometimes over 15 h or more, for international flights. This large volume of travelers, combined with their time spent in close proximity of each other, during flights increases the potential for transmitting diseases, such as severe acute respiratory syndrome (SARS), tuberculosis, swine influenza (H1N1), and avian influenza (H5N1). Consequently, a common concern during commercial flight is disease transfer among passengers. Airborne pathogens travel throughout aircraft cabins much as airborne particles would. To study how these airborne diseases travel, particles were released into a Boeing 767 aircraft cabin mockup, and the particle deposition rates over a variety of locations were measured. In addition to varying the location of measurements, the surface orientation for measurements was changed between horizontal and vertical configurations. The number of particles that deposited onto a clear tape for each location was optically counted using a photographic type microscope. The microscope limited the particle detection size to particles with diameters greater than 3.0 μm. The particle deposition measurements were then compared to previous air concentration measurements taken in the same mockup aircraft cabin. It was found that the surface orientation played a significant role in particle deposition. Nearly a factor of ten differences in particle counts was observed between the vertical and horizontal surface orientations. In addition, the deposition trend in the mockup cabin, left to right for horizontal orientation, reversed when the surface orientation was changed.

Source apportionment of airborne particles in commercial aircraft cabin environment: Contributions from outside and inside of cabin

Airborne particles are an important type of air pollutants in aircraft cabin. Finding sources of particles is conducive to taking appropriate measures to remove them. In this study, measurements of concentration and size distribution of particles larger than 0.3 μm (PM>0.3) were made on nine short haul flights from September 2012 to March 2013. Particle counts in supply air and breathing zone air were both obtained. Results indicate that the number concentrations of particles ranged from 3.6 × 102 counts L−1 to 1.2 × 105 counts L−1 in supply air and breathing zone air, and they first decreased and then increased in general during the flight duration. Peaks of particle concentration were found at climbing, descending, and cruising phases in several flights. Percentages of particle concentration in breathing zone contributed by the bleed air (originated from outside) and cabin interior sources were calculated. The bleed air ratios, outside airflow rates and total airflow rates were calculated by using carbon dioxide as a ventilation tracer in five of the nine flights. The calculated results indicate that PM>0.3 in breathing zone mainly came from unfiltered bleed air, especially for particle sizes from 0.3 to 2.0 μm. And for particles larger than 2.0 μm, contributions from the bleed air and cabin interior were both important. The results would be useful for developing better cabin air quality control strategies.

Differential Diagnosis of Subjective Workload and Styles of Coping with Stress among Aircraft Crewmembers

2013 | Volume19 | Issue 4 | 11 This publication concerns psychological characterization of workload and coping with stress among commercial aircraft crews. Analysis was conducted on two study groups: experimental group – pilots (n=19) and commercial aircraft cabin crew (n=22), and control group – shopping mall employees (n=28). Occupational task load was assessed using Polish version of NASA-TLX tool. Styles of coping with stress were evaluated using Polish version of Coping Inventory for Stressful Situations (CISS) by N.S. Endler and D.A. Parker. We validated diff erences between pilots and aircraft cabin crew and control group both with regard to the style of coping with stress as well as specifi cs of occupational burden. It was noted that assessment of both subjective workload and styles of coping with stress among pilots and aircraft personnel in comparison to control group also characterizes work specifi cs for both of those vocational groups. Methods of studying subjective workload and styles of coping with stress may be used for diff erential diagnosis of task-related aspects of various vocations. pilots, aircraft personnel, workload, coping with stress DIFFERENTIAL DIAGNOSIS OF SUBJECTIVE WORKLOAD AND STYLES OF COPING WITH STRESS AMONG AIRCRAFT CREWMEMBERS

Investigation of the role for noise canceling headphones to assist speech recall in noise

There are many situations where it is necessary to hear, understand and be able to recall spoken information in less than ideal listening conditions. For example within an aircraft cabin where, despite improvements in modern passenger aircraft, noise generated from aircraft engines and aerodynamic airflow make it difficult to hear important on-board safety announcements such as the preflight safety brief. The benefits of headphones that incorporate active noise control in such environments are the focus of a series of research studies. In this paper, we discuss the techniques developed to investigate the use of active noise control headphones on the intelligibility and recall of speech generated outside the headsets in noise typical of that in a commercial aircraft cabin. The initial studies were directed towards assessing the effects on the recall for safety announcements. These studies have been extended to investigate if there are any benefits for those for which English is a second language. The results suggest that the use of active noise control headphones can minimize communication errors in a range of situations and this paper will discuss the methodology adopted and summarize the outcomes.

Furry pet allergens, fungal DNA and microbial volatile organic compounds (MVOCs) in the commercial aircraft cabin environment

There has been concern about the cabin environment in commercial aircraft. We measured cat, dog and horse allergens and fungal DNA in cabin dust and microbial volatile organic compounds (MVOCs) in cabin air. Samples were collected from two European airline companies, one with cabins having textile seats (TSC) and the other with cabins having leather seats (LSC), 9 airplanes from each company. Dust was vacuumed from seats and floors in the flight deck and different parts of the cabin. Cat (Fel d1), dog (Can f1) and horse allergens (Equ cx) were analyzed by ELISA. Five sequences of fungal DNA were analyzed by quantitative PCR. MVOCs were sampled on charcoal tubes in 42 TSC flights, and 17 compounds were analyzed by gas chromatography mass spectrometry (GC-MS) with selective ion monitoring (SIM). MVOC levels were compared with levels in homes from Nordic countries. The weight of dust was 1.8 times larger in TSC cabins as compared to LSC cabins (p < 0.001). In cabins with textile seats, the geometric mean (GM) concentrations of Fel d1, Can f1 and Equ cx were 5359 ng g(-1), 6067 ng g(-1), and 13 703 ng g(-1) (GM) respectively. Levels of Fel d1, Can f1 and Equ cx were 50 times, 27 times and 75 times higher respectively, in TSC cabins as compared to LSC cabins (p < 0.001). GM levels of Aspergillus/Penicillium DNA, Aspergillus versicolor DNA, Stachybotrys chartarum DNA and Streptomyces DNA were all higher in TSC as compared to LSC (p < 0.05). The sum of MVOCs in cabin air (excluding butanols) was 3192 ng m(-3) (GM), 3.7 times higher than in homes (p < 0.001) and 2-methyl-1-butanol and 3-methyl-1-butanol concentrations were 15-17 times higher as compared to homes (p < 0.001). Concentrations of isobutanol, 1-butanol, dimethyldisulfide, 2-hexanone, 2-heptanone, 3-octanone, isobutyl acetate and ethyl-2-methylbutyrate were lower in cabin air as compared to homes (p < 0.05). In conclusion, textile seats are much more contaminated by pet allergens and fungal DNA than leather seats. The use of seats with smooth surfaces should be encouraged. The MVOC levels differed between cabin air and homes.