Cabin Environment

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 4578 Experts worldwide ranked by ideXlab platform

Qingyan Chen - One of the best experts on this subject based on the ideXlab platform.

  • evaluating the commercial airliner Cabin Environment with different air distribution systems
    Indoor Air, 2019
    Co-Authors: Daniel Wei, Chao-hsin Lin, Ruoyu You, Qingyan Chen
    Abstract:

    Ventilation systems for commercial airliner Cabins are important in reducing contaminant transport and maintaining thermal comfort. To evaluate the performance of a personalized displacement ventilation system, a conventional displacement ventilation system, and a mixing ventilation system, this study first used the Wells-Riley equation integrated with CFD to obtain the SARS quanta value based on a specific SARS outbreak on a flight. This investigation then compared the three ventilation systems in a seven-row section of a fully occupied, economy-class Cabin in Boeing 737 and Boeing 767 airplanes. The SARS quanta generation rate obtained for the index patient could be used in future studies. For all the assumed source locations, the passengers' infection risk by air in the two planes was the highest with the mixing ventilation system, while the conventional displacement ventilation system produced the lowest risk. The personalized ventilation system performed the best in maintaining Cabin thermal comfort and can also reduce the infection risk. This system is recommended for airplane Cabins.

  • an innovative personalized displacement ventilation system for airliner Cabins
    Building and Environment, 2018
    Co-Authors: Ruoyu You, Daniel Wei, Chao-hsin Lin, Junjie Liu, Qingyan Chen, Yongzhi Zhang, Xingwang Zhao
    Abstract:

    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 and maintain 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.

  • experimental and numerical study of airflow distribution in an aircraft Cabin mock up with a gasper on
    Journal of Building Performance Simulation, 2016
    Co-Authors: Ruoyu You, Daniel Wei, Chao-hsin Lin, Jun Chen, Zhu Shi, Wei Liu, Qingyan Chen
    Abstract:

    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–e 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–e model for predicting the airflow distribution in gasper-induced jet dominant region in an aircraft Cabin.

  • accurate and high resolution boundary conditions and flow fields in the first class Cabin of an md 82 commercial airliner
    Atmospheric Environment, 2012
    Co-Authors: Wei Liu, Chao-hsin Lin, Junjie Liu, Jizhou Wen, Jiangyue Chao, Weiyou Yin, Chen Shen, Dayi Lai, Hejiang Sun, Qingyan Chen
    Abstract:

    Abstract Flow fields in commercial airliner Cabins are crucial for creating a thermally comfortable and healthy Cabin Environment. Flow fields depend on the thermo-fluid boundary conditions at the diffusers, in addition to the Cabin geometry and furnishing. To study the flow fields in Cabins, this paper describes a procedure to obtain the Cabin geometry, boundary conditions at the diffusers, and flow fields. This investigation used a laser tracking system and reverse engineering to generate a digital model of an MD-82 aircraft Cabin. Even though the measuring error by the system was very small, approximations and assumptions were needed to reduce the workload and data size. The geometric model can also be easily used to calculate the space volume. A combination of hot-sphere anemometers (HSA) and ultrasonic anemometers (UA) were applied to obtain the velocity magnitude, velocity direction, and turbulence intensity at the diffusers. The measured results indicate that the flow boundary conditions in a real Cabin were rather complex and the velocity magnitude, velocity direction, and turbulence intensity varied significantly from one slot opening to another. UAs were also applied to measure the three-dimensional air velocity at 20 Hz, which could also be used to determine the turbulence intensity. Due to the instability of the flow, it should at least be measured for 4 min to obtain accurate averaged velocity and turbulence information. It was found that the flow fields were of low speed and high turbulence intensity. This study provides high quality data for validating Computational Fluid Dynamics (CFD) models, including Cabin geometry, boundary conditions of diffusers, and high-resolution flow field in the first-class Cabin of a functional MD-82 commercial airliner.

  • simulations of ozone distributions in an aircraft Cabin using computational fluid dynamics
    Atmospheric Environment, 2012
    Co-Authors: Aakash C Rai, Qingyan Chen
    Abstract:

    Abstract Ozone is a major pollutant of indoor air. Many studies have demonstrated the adverse health effect of ozone and the byproducts generated as a result of ozone-initiated reactive chemistry in an indoor Environment. This study developed a Computational Fluid Dynamics (CFD) model to predict the ozone distribution in an aircraft Cabin. The model was used to simulate the distribution of ozone in an aircraft Cabin mockup for the following cases: (1) empty Cabin; (2) Cabin with seats; (3) Cabin with soiled T-shirts; (4) occupied Cabin with simple human geometry; and (5) occupied Cabin with detailed human geometry. The agreement was generally good between the CFD results and the available experimental data. The ozone removal rate, deposition velocity, retention ratio, and breathing zone levels were well predicted in those cases. The CFD model predicted breathing zone ozone concentration to be 77–99% of the average Cabin ozone concentration depending on the seat location. The ozone concentration at the breathing zone in the Cabin Environment can better assess the health risk to passengers and can be used to develop strategies for a healthier Cabin Environment.

Chao-hsin Lin - One of the best experts on this subject based on the ideXlab platform.

  • evaluating the commercial airliner Cabin Environment with different air distribution systems
    Indoor Air, 2019
    Co-Authors: Daniel Wei, Chao-hsin Lin, Ruoyu You, Qingyan Chen
    Abstract:

    Ventilation systems for commercial airliner Cabins are important in reducing contaminant transport and maintaining thermal comfort. To evaluate the performance of a personalized displacement ventilation system, a conventional displacement ventilation system, and a mixing ventilation system, this study first used the Wells-Riley equation integrated with CFD to obtain the SARS quanta value based on a specific SARS outbreak on a flight. This investigation then compared the three ventilation systems in a seven-row section of a fully occupied, economy-class Cabin in Boeing 737 and Boeing 767 airplanes. The SARS quanta generation rate obtained for the index patient could be used in future studies. For all the assumed source locations, the passengers' infection risk by air in the two planes was the highest with the mixing ventilation system, while the conventional displacement ventilation system produced the lowest risk. The personalized ventilation system performed the best in maintaining Cabin thermal comfort and can also reduce the infection risk. This system is recommended for airplane Cabins.

  • an innovative personalized displacement ventilation system for airliner Cabins
    Building and Environment, 2018
    Co-Authors: Ruoyu You, Daniel Wei, Chao-hsin Lin, Junjie Liu, Qingyan Chen, Yongzhi Zhang, Xingwang Zhao
    Abstract:

    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 and maintain 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.

  • routes of transmission of influenza a h1n1 sars cov and norovirus in air Cabin comparative analyses
    Indoor Air, 2018
    Co-Authors: Hao Lei, Chao-hsin Lin, Shenglan Xiao, Sharon L Norris, Daniel Wei
    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.

  • experimental and numerical study of airflow distribution in an aircraft Cabin mock up with a gasper on
    Journal of Building Performance Simulation, 2016
    Co-Authors: Ruoyu You, Daniel Wei, Chao-hsin Lin, Jun Chen, Zhu Shi, Wei Liu, Qingyan Chen
    Abstract:

    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–e 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–e model for predicting the airflow distribution in gasper-induced jet dominant region in an aircraft Cabin.

  • source apportionment of airborne particles in commercial aircraft Cabin Environment contributions from outside and inside of Cabin
    Atmospheric Environment, 2014
    Co-Authors: Jun Guan, Xudong Yang, Chao-hsin Lin
    Abstract:

    Abstract 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.

Tengfei Zhang - One of the best experts on this subject based on the ideXlab platform.

  • inverse design of aircraft Cabin Environment using computational fluid dynamics based proper orthogonal decomposition method
    Indoor and Built Environment, 2017
    Co-Authors: Jihong Wang, Tengfei Zhang, Hongbiao Zhou, Shugang Wang
    Abstract:

    To design a comfortable aircraft Cabin Environment, designers conventionally follow an iterative guess-and-correction procedure to determine the air-supply parameters. The conventional method has a...

  • inverse design of underfloor heating power rates and air supply temperature for an aircraft Cabin
    Applied Thermal Engineering, 2016
    Co-Authors: Lei Lei, Shugang Wang, Tengfei Zhang
    Abstract:

    Abstract Thermal boundary conditions in commercial airliner Cabins are crucial for creating a comfortable Cabin Environment. Cabin temperature distributions depend on the thermo-fluid boundary conditions of the boundary walls and the air supply. This paper proposed a combined inverse-forward model for designers to determine the total underfloor heating rates and the air-supply temperature in an aircraft Cabin. The contribution ratio of indoor climate (CRI) is applied to describe the cause–effect relationship between the boundary wall convective heat release rates and the resulting temperature rise at certain points, which can be cast into a matrix. The solution contains three sub-models: (i) regularized inversion of the cause–effect matrix with the target Cabin air temperatures as the known input, which solves the convective heat rates of the underfloor heaters and the air-supply temperature, (ii) solution of underfloor heater's surface temperatures based on Newton's law of cooling, and (iii) computation of the radiative heat rates. The above model was used to determine the total underfloor heating rates and air-supply temperature in a single-aisle aircraft Cabin. The design targets are to create an average temperature of 24 °C near the upper human body and 26 °C at the ankle level. An experimental test was conducted in a simplified half section of an aircraft Cabin for model validation. The results show that the proposed methodology is able to provide the total underfloor heating rates and air-supply temperature in good agreement with the measurement data and forward-simulation boundary conditions.

  • a personal air distribution system with air terminals embedded in chair armrests on commercial airplanes
    Building and Environment, 2012
    Co-Authors: Tengfei Zhang, Shugang Wang
    Abstract:

    Abstract A mixing air distribution system is currently used on airplanes, which supplies cool air at high momentum from the ceiling level and extracts the contaminated air at the deck level. However, such highly mixing context has led to numerous complaints not just for air quality but also for thermal comfort. To improve aircraft Cabin Environment, this investigation has proposed a personal chair-armrest-embedded air system. The system delivers conditioned, outside air directly to the breathing zone of a passenger from the air terminal devices embedded within both chair armrests. While simultaneously, a part of outside air mixed together with most of the recirculated air is supplied from the perforated under-aisle panels, and the contaminated air is extracted through the overhead exhausts on the ceiling. To assure thermal comfort, the personal air is conditioned to 25 °C in relative humidity of either 15% or 30%, so the Cabin is mainly cooled down by the air supplied from the under-aisle panels. After elaborate investigation with experimental test and computational fluid dynamics (CFD) modeling, this study finds that by combining the under-aisle air supply with the personal air supply at the chair armrests, the system is robust to prevent the contaminants released at any height to the passenger’s breathing region. Though there is vertical temperature stratification, the system is acceptable in perspective of percent dissatisfied due to draught risk. To aid for personal air system design, some optimal basic parameters are recommended.

  • theoretical modeling approaches to investigating the spread of disease in airports and on aircraft advance models for predicting contaminants and infectious disease virus transport inthe airliner Cabin Environment part 1
    Research on the Transmission of Disease in Airports and on Aircraft: A SynposiumAirport Cooperative Research Program, 2010
    Co-Authors: Qingyan Chen, Tengfei Zhang, Sagnik Mazumdar, Michael W Plesniak, Stephane Poussou, Paul E Sojka, Zhao Zhang
    Abstract:

    Computational fluid dynamics (CFD) is a very attractive tool to study the transmission of airborne contaminants in an airliner Cabin as it is inexpensive and flexible in changing thermofluid conditions inside the Cabins compared with experimental measurements. The results presented here illustrate the potential of using CFD in modeling gaseous and particulate contaminant transport inside airliner Cabins. CFD was also used to model the SARS transmission case in Air China Flight 112 from Hong Kong to Beijing in 2003 where a contagious passenger infected some 20 fellow passengers. Some seated as far as seven rows from the contagious passenger were infected. The movement of passengers and crew members may play a role in transmission.

  • experimental and numerical investigation of airflow and contaminant transport in an airliner Cabin mockup
    Building and Environment, 2009
    Co-Authors: Zhao Zhang, Tengfei Zhang, Sagnik Mazumdar, Xi Chen, Qingyan Chen
    Abstract:

    Abstract The study of airflow and contaminant transport in airliner Cabins is very important for creating a comfortable and healthy Environment. This paper shows the results of such a study by conducting experimental measurements and numerical simulations of airflow and contaminant transport in a section of half occupied, twin-aisle Cabin mockup. The air velocity and air temperature were measured by ultrasonic and omni-directional anemometers. A gaseous contaminant was simulated by a tracer gas, sulfur hexafluoride or SF6, and measured by a photo-acoustic multi-gas analyzer. A particulate contaminant was simulated by 0.7 μm di-ethyl-hexyl-sebacat (DEHS) particles and measured by an optical particle sizer. The numerical simulations used the Reynolds averaged Navier–Stokes equations based on the RNG k–e model to solve the air velocity, air temperature, and gas contaminant concentration; and employed a Lagrangian method to model the particle transport. The numerical results quantitatively agreed with the experimental data while some remarkable differences exist in airflow distributions. Both the experimental measurements and computer simulations were not free from errors. A complete and accurate validation for a complicated Cabin Environment is challenging and difficult.

Ruoyu You - One of the best experts on this subject based on the ideXlab platform.

  • evaluating the commercial airliner Cabin Environment with different air distribution systems
    Indoor Air, 2019
    Co-Authors: Daniel Wei, Chao-hsin Lin, Ruoyu You, Qingyan Chen
    Abstract:

    Ventilation systems for commercial airliner Cabins are important in reducing contaminant transport and maintaining thermal comfort. To evaluate the performance of a personalized displacement ventilation system, a conventional displacement ventilation system, and a mixing ventilation system, this study first used the Wells-Riley equation integrated with CFD to obtain the SARS quanta value based on a specific SARS outbreak on a flight. This investigation then compared the three ventilation systems in a seven-row section of a fully occupied, economy-class Cabin in Boeing 737 and Boeing 767 airplanes. The SARS quanta generation rate obtained for the index patient could be used in future studies. For all the assumed source locations, the passengers' infection risk by air in the two planes was the highest with the mixing ventilation system, while the conventional displacement ventilation system produced the lowest risk. The personalized ventilation system performed the best in maintaining Cabin thermal comfort and can also reduce the infection risk. This system is recommended for airplane Cabins.

  • an innovative personalized displacement ventilation system for airliner Cabins
    Building and Environment, 2018
    Co-Authors: Ruoyu You, Daniel Wei, Chao-hsin Lin, Junjie Liu, Qingyan Chen, Yongzhi Zhang, Xingwang Zhao
    Abstract:

    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 and maintain 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.

  • experimental and numerical study of airflow distribution in an aircraft Cabin mock up with a gasper on
    Journal of Building Performance Simulation, 2016
    Co-Authors: Ruoyu You, Daniel Wei, Chao-hsin Lin, Jun Chen, Zhu Shi, Wei Liu, Qingyan Chen
    Abstract:

    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–e 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–e model for predicting the airflow distribution in gasper-induced jet dominant region in an aircraft Cabin.

Junjie Liu - One of the best experts on this subject based on the ideXlab platform.

  • an innovative personalized displacement ventilation system for airliner Cabins
    Building and Environment, 2018
    Co-Authors: Ruoyu You, Daniel Wei, Chao-hsin Lin, Junjie Liu, Qingyan Chen, Yongzhi Zhang, Xingwang Zhao
    Abstract:

    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 and maintain 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.

  • Evaluation of relative weights for temperature, CO2, and noise in the aircraft Cabin Environment
    Building and Environment, 2018
    Co-Authors: Susu Jia, Dayi Lai, Jian Kang, Junjie Liu
    Abstract:

    Abstract As people are increasingly traveling by air, the aircraft Cabin Environment has received considerable attention in recent years. Temperature, CO2, and noise can influence the Cabin Environment, but their relative importance is unknown. This paper combined data from an objective mental performance test and a subjective questionnaire survey to obtain the relative weights of these three parameters in the aircraft Cabin Environment. Our analyses indicated that the relative weights of temperature, CO2, and noise in the Cabin Environment were 0.4717, 0.2010, and 0.3273 respectively, under summer conditions and 0.5854, 0.1737, and 0.2409, respectively, under winter conditions. In different temperature conditions, the mental performance test results were better in colder temperature. Since we observed a warmer thermal sensation under higher levels of CO2 and noise, we have proposed an adjusted comfort zone for the aircraft Cabin. The new zone has a lower temperature than that of the traditional thermal comfort zone. The results of this study provide useful information for engineers and designers as they seek to improve the Cabin Environment.

  • near fields of gasper jet flows with wedged nozzle in aircraft Cabin Environment
    Building and Environment, 2017
    Co-Authors: Zhanqi Tang, Nan Jiang, Yong Guo, Xujia Cui, Shen Dai, Junjie Liu
    Abstract:

    Abstract The geometry of the outlet nozzle has a direct effect on the near fields of turbulent jets. An attempt is made to modify the gasper jet nozzle by adding wedges of different sizes. The near fields of the wedged gasper jets are measured by a hot-wire anemometer. For the with-wedges cases, the mean velocity exhibits a more rapid decay in the axial direction, and the turbulent intensity is attenuated after the “second potential core.” The higher-order statistics, such as skewness and kurtosis, indicate no obvious difference in the downstream region. As the turbulent structures are formed, the energy spectra indicate that their average energy increases under the wedges' perturbation. Then, the anti-axial-symmetry of the transition flows is observed in two characteristic planes. The mean velocity does not exhibit a significant difference between the two planes, but the turbulent intensity in the perturbed plane embodies the wedges' influence. The wedged nozzle affects the energy intensity and diffusion angle of the turbulent structures in the perturbed plane, and the difference from the unperturbed plane is confirmed by the discrepancy spectra. Furthermore, the anti-axial-symmetry is characterized by turbulent intermittency and entrainment. The turbulent intermittency in the perturbed plane performs with a lower value in the near-nozzle region, and evolves into axial-symmetry in the further downstream region. For turbulent entrainment, the entrainment ratio manifests that wedged nozzle reduces the flow mass in the entrainment of ambient air in the downstream region.

  • PIV methods for quantifying human thermal plumes in a Cabin Environment without ventilation
    Journal of Visualization, 2017
    Co-Authors: Jiayu Li, Congcong Wang, Junjie Liu, Nan Jiang, Xiaodong Cao
    Abstract:

    The role that thermal plumes play becomes more crucial, especially in a densely occupied space, such as an aircraft Cabin. In this paper, the aim is to isolate this effect and to investigate the air distribution of individual human thermal plumes in the Cabin. For this purpose, the thermal plume conditions in the aircraft Cabin have been developed without any ventilation. The experimental procedure to quantify the air distribution of thermal plumes with both high temporal and spatial resolution was built with two different types of 2D particle image velocimetry (PIV) systems, and the reliability and repeatability of the measured data were verified. With such reliable data, the numerical models can be validated and improved in the future. In addition, certain phenomena were revealed in this research. From the time-averaged velocity fields, the thermal plumes were greatly influenced by the particular aircraft Cabin geometry and restricted by the relatively small space and the maximum speed presented behind the manikin’s head. Through a time series analysis of instantaneous air distributions, the thermal plumes appeared one after another with a period of approximately 5 s, and the multi-scale characteristics of both time and intensity were observed by monitoring the instantaneous velocity of a typical point.Graphical abstract

  • turbulent characteristics in the near fields of gasper jet flows in an aircraft Cabin Environment intermittently energetic coherent structures
    Building and Environment, 2017
    Co-Authors: Zhanqi Tang, Nan Jiang, Yong Guo, Xujia Cui, Shen Dai, Junjie Liu
    Abstract:

    Abstract In an aircraft Cabin Environment, a gasper nozzle is a type of air conditioning and part of the air-recirculation system, and its near fields are dominated by intermittently energetic coherent structures (IECSs). Based on the percentage of dissatisfied (PD) model, the turbulent intensity and the intermittent frequency of IECSs are investigated in this study as main factors of draught sensation. The gasper jet flow fields at several Reynolds numbers (Re = 2000~17,047) are determined using a hot-wire anemometer, and a round-pipe jet flow is used for comparison. The mean velocity and streamwise gradient exhibit self-similarity after the reattachment point. Pre-multiplied energy spectra provide the energetic length scales of the intermittent coherent structures. Then, continuous wavelet transform is employed to detect the IECSs. The average waveform indicates that along the axis direction, the IECSs exhibit unstable coherence, symmetric and oscillating waveforms. All of these signatures are independent of the nozzle geometry and display an earlier emergence with an increase in Re. Furthermore, the mean turbulent intensity and waiting time of the IECSs are explored. Compared with the round-pipe jet, the IECSs in the gasper jet flows have a lower mean turbulent intensity. The analysis of the probability density function indicates that the waiting time between the successive IECSs is almost twice that of the energetic length scale, and the dimensionless result presents that the intermittent frequency has the self-similar distribution for all the cases in this study.