A Preliminary Numerical Investigation of Airborne Droplet Dispersion in Aircraft Cabins

The emergence of the novel coronavirus has led to a global pandemic which has led to the airline industry facing severe losses. For air travel to recover, airlines need to ensure safe air travel. In this paper, the authors have modeled droplet dispersion after a single breath from an index patient. Computational Fluid Dynamics (CFD) simulations are conducted using the k-ωSST turbulence model in ANSYS Fluent. The authors have taken into consideration several parameters such as the size of the mouth opening, the velocity of the cabin air as well as the number of droplets being exhaled by the index patient to ensure a realistic simulation. Preliminary results indicate that after a duration of 20 s, droplets from the index patient disperse within a 10 m2 cabin area. About 75% of the droplets are found disperse for up to 2 m axially behind the index patient. This could possess an enhanced risk to passengers sitting behind the index patient. Ultimately, this paper provides an insight into the potential of CFD to visualise droplet dispersal and give impetus to ensure that necessary mitigating measures can be taken to reduce the risk of infection through droplet dispersal.

A model for aircraft cabin evacuation considering passenger type

Pedestrian safety evacuation in aircraft cabins has been a challenging problem because of the aircraft’s unique characteristics,such as the diversity of passengers and the restricted evacuation environment.It is difficult to reproduce evacuation activities in aircraft cabin due to safety concerns and cost constraints.To fill this gap,an improved cellular automaton model of crowd evacuation for aircraft cabin is established by incorporating the characteristics of cabin space structures and passenger attributes.Passengers are divided into healthy individual passengers and disabled-healthy group passengers,whose movement mechanisms are quantified.Based on the constructed model,simulation experiments are conducted using the configuration cabin layout of B737-800 as an example.The results show that the evacuation time is prolonged with increased passenger density and the number of disabled passengers.Moreover,the overall evacuation time is insignificantly affected by whether disabled-healthy group passengers’seats are close to the aisle or window,and the evacuation efficiency is best when their seats are evenly distributed in the cabin.The evacuation time is the shortest when all cabin doors are open,and pedestrians are evacuated the slowest when the central emergency doors are closed.This study pro-vides valuable insights into effective strategies for pedestrian evacuation and crowd emergency management of civil aircraft.

Airborne transmission of virus-laden droplets in an aircraft cabin

This study investigates the airborne transmission of virus-laden droplets generated by a cough of patients in an aircraft cabin to reveal the infection risk of taking an airplane.The influence of the ventilation system on the flow feld of the cabin was analysed to reveal its effects on the airbore transmission ofvirus-laden droplets.Meanwhile.human body heat was also considered in the simulations.The results show that hot plume due to human body hent has a significant impact on the upward movement of virus-laden droplets.The virus-laden droplets expelled by a cough can be transmitted to the region two to three rows away from the generator.Particularly,the transverse motion present in the early stage of the droplet transmission results in a high infection risk to the passengers in the same row as the patient.This work gives insight into the understanding of the airborne transmission of virus-laden droplets in the entire passenger cabin.

Thermal comfort assessment in civil aircraft cabins

Aircraft passengers are more and demanding in terms of thermal comfort. But it is not yet easy for aircraft crew to control the environment control system （ECS） that satisfies the thermal comfort for most passengers due to a number of causes. This paper adopts a corrected predicted mean vote （PMV） model and an adaptive model to assess the thermal comfort conditions for 31 investigated flights and draws the conclusion that there does exist an uncomfortable thermal phe- nomenon in civil aircraft cabins, especially in some short-haul continental flights. It is necessary to develop an easy way to predict the thermal sensation of passengers and to direct the crew to con- trol ECS. Due to the assessment consistency of the corrected PMV model and the adaptive model, the adaptive model of thermal neutrality temperature can be used as a method to predict the cabin optimal operative temperature. Because only the mean outdoor effective temperature ET＊ of a departure city is an input variable for the adaptive model, this method can be easily understood and implemented by the crew and can satisfy 80-90% of the thermal acceptability levels of passen- gers.

Simulation Analysis of Electromechanical Coupling for Unmanned Aerial Vehicle Cabin Door System

In order to study the dynamic response of the unmanned aerial vehicle cabin door opening and closing system under impact load conditions, considering the flexible treatment of mechanical components, and the system’s motion with different stiffness of energy-absorbing components, a rigid-flexible coupling model of the cabin door actuation system was established in LMS. Virtual. Motion. In Amesim, a control model of the motor was created. Through the Motion-Amesim co-simulation module, the dynamic module of the system was combined with the motor control module to complete the electromechanical coupling simulation and analyze the results. .

基于扩展TPB的客舱旅客非适应性疏散行为影响研究

为了研究客舱旅客非适应性疏散行为对疏散效率的影响及作用机理,引入认知程度、感知风险及感知价值3个变量,基于扩展TPB理论构建飞机旅客非适应性疏散行为意向模型,通过调查问卷收集数据并验证模型可行性。研究结果表明:知觉行为控制、主观规范和行为态度正向影响行为意向,感知风险、认知程度和感知价值间接影响行为意向,感知风险直接负向影响行为意向,认知程度和感知价值对行为意向无直接影响。研究结果可为飞机客舱紧急疏散提出针对性建议。

机舱环境5G信道传播模型及信号覆盖研究

针对机舱无线通信覆盖不全面、速度慢、不稳定等问题,该文基于射线跟踪方法构建了机舱环境第5代移动通信技术(5th generation mobile communication technology,5G)信道模型,并分析了信号覆盖能力及信道参数特性。首先,利用三角面元对真实的机舱环境进行三维几何重构,以降低射线跟踪方法获取信道参数的复杂度;然后,结合分簇算法构建5G信道传播模型,进而分析了机舱环境下5G信号覆盖和通信性能。仿真分析结果表明,簇功率偏移和簇时延偏移服从高斯分布,簇到达方位角和簇到达俯仰角偏移服从拉普拉斯分布,同时发现,机舱环境中的密集散射体是影响5G信号覆盖范围的关键因素。上述结论可用于机舱环境5G基站的无线通信信号覆盖预测和多径参数评估等领域。

基于DIALux的飞机客舱照明设计方法

飞机客舱照明是飞机内部照明系统的重要组成部分,合理的客舱照明设计可以提高飞行服务质量、提升旅客满意度和舒适度。基于DIALux计算仿真软件,提出了一种飞机客舱照明设计方法。从旅行安全、视觉舒适度、高品质服务等角度出发,通过对平均照度、眩光、照度均匀度等多方面的量化评估、校核与分析,探讨并提出了具有创新性的飞机客舱的照明设计方法。基于此方法以某型号飞机客舱为研究对象建立光学仿真模型、进行视觉仿真计算,验证了该方法的可行性。

横滚姿态下飞机客舱火灾数值模拟研究

为研究飞机不同横滚角度下客舱火灾发展规律,利用PyroSim搭建国产单通道客机客舱火灾模型,通过分析客舱烟气层高度、温度、CO体积分数变化,得到客舱及翼上出口处的可用疏散时间(ASET)。研究结果表明:影响客舱内部ASET的首要因素是温度,而影响翼上出口处ASET的则是CO;飞机横滚会导致客舱火灾高温区域由同侧壁向客舱前后两端蔓延,导致温度纵向影响跨度增大,但高温区域面积减小;横滚姿态下飞机翼上出口处温度上升时间延后,且最高温度降低;横滚角度增大会使翼上出口处ASET增加,但对前后舱门处影响不明显。研究结果可为航空器横滚姿态下的火灾疏散提供一定参考。

粒子群算法优化支持向量回归的民机客舱座椅舒适度评价预测

为建立民机客舱座椅舒适度主客观评价之间复杂非线性的评价预测模型,同时提高模型的预测精度,本文将支持向量回归(Support vector regression,SVR)中的惩罚参数C、通道控制参数ε以及核函数参数σ作为优化目标,利用粒子群算法(Particle swarm optimization,PSO)寻找全局最优参数,建立PSO-SVR人-民机客舱座椅舒适度评价预测模型,并对预测结果进行对比分析。分析结果表明:与BP神经网络(Back propagation,BP)模型相比,支持向量回归模型具有良好的鲁棒性;与SVR模型相比,PSO-SVR模型预测精度更高,误差波动小,预测结果均方误差(MSE)降低了85.95%,决定系数(R2)提高了15.42%。因此粒子群算法可以有效提高支持向量回归模型的预测精度和泛化能力。

基于正则化声压匹配法的舱室声场复现

舱室噪声控制、声品质设计等研究通常需开展大量的声场测试试验,由于舱室实际试验成本较高,因此通过声场复现的方式在舱室模拟舱中复现所需求的声学环境,对于降低研究成本、开展重复性试验具有重要意义。本文面向舱室声环境复现需求,以经典声压匹配法为基础,建立了基于扬声器阵列输出的多目标点位协同复现算法,通过引入正则化技术,使算法对实际测试中的各类噪声具有更强的鲁棒性。在一个实际舱室模拟舱环境中搭建了复现系统,复现试验表明,本文算法可在指定舱内的多个点位上协同复现目标频响曲线,在宽频范围内相对误差小于5%,具有良好的精度,在舱室声环境复现应用中具有良好的前景。

基于嵌入式系统的表面划痕测量装置的设计与实现

针对飞机机身蒙皮、座舱玻璃等装备零部件表面的划痕深度和宽度现场定量检测的需求,研制了一套基于嵌入式系统的表面划痕测量装置。装置基于光切原理设计,以嵌入式ARM(advanced RISC machines)开发板为硬件平台,连接工业相机和显微镜组,采集由投射光路投射出的平行光条并经过被测表面调制后的图像,经过图像处理和划痕特征提取,计算划痕的深度和宽度,测量结果可数字化显示并保存。试验结果表明,装置在0.005~0.060 mm测量范围内的示值误差不超过±2.0μm,在0.060~2.000 mm的测量范围内的相对示值误差优于±4%。测量装置具备小型化、一体化、高精度、快速、易操作等特点,适用于在现场环境中对飞机机身各处的划痕进行直接测量。

考虑入水冲击过程的舱段结构优化

水陆两栖飞机的舱段结构在入水过程中需要承受入水冲击力的作用,对水陆两栖飞机的结构性能有着重要影响。本文建立了水陆两栖飞机的初始舱段结构模型,基于该结构通过数值仿真方法获取了结构入水过程中的压强分布。建立了舱段结构的有限元模型并开展了参数分析,探究了不同设计参数对舱段结构的影响。在此基础上,考虑舱段入水过程中的结构变形与应力分布,搭建了舱段结构优化设计框架;以舱段结构的应力和应变作为约束、减少质量为目标开展优化设计;根据优化后得到的舱段结构,进一步验证了单向耦合分析方法的准确性。优化结果表明,舱段结构的底面加强筋分布以及底面蒙皮厚度对入水过程中结构产生的最大米塞斯应力有着重要影响。通过对舱段结构的设计参数开展优化设计,可以在满足强度与刚度的前提下,显著降低舱段结构的质量。

Current studies on air distributions in commercial airliner cabins

Abstract Air distribution in commercial airliner cabins is very important for the comfort and health of passengers and crew. Experimental measurements, computational fluid dynamics （CFD） simulations, and inverse modeling are state-of-the-art methods available for studying the air distri- bution. This paper gave an overview of the different experimental models, such as scale models, simplified models, full-scale mockups, and actual air cabins. Although experimental measurements were expensive and time consuming, the data were essential for validating CFD simulations. Different modeling strategies for CFD simulations were also discussed in this paper, including large eddy simulations and Reynolds averaged Navier-Stokes equation modeling. CFD simulations were main stream approaches for studying the air distribution but they could not easily lead to optimal design. Inverse modeling of air distribution has recently emerged into a very powerful and attractive tool for designing the air distribution in airliner cabins, although most of the studies were preliminary.

基于人机工程学的民用飞机舱门操作面板设计

在当前民用飞机舱门操作面板设计中,人机功效和界面设计缺少统一的标准和规范,设计过程过于依赖个人经验和自身偏好,导致所设计的操作面板在使用过程中人机功效较差。为此,基于人机工程学原理讨论了民用飞机舱门操作面板显示与操作的设计原则,并提出了一种集中式舱门操作面板及区域控制面板的设计方案。首先通过问卷调查来确定舱门操作面板的信息组织、编码、显示元素和显示形式等,然后构建舱门操作面板、区域控制面板以及飞机的三维模型,最后使用人机工程仿真软件DELMIA对操作面板的布置、按键尺寸和触及域进行了动态操作仿真。仿真结果表明,所设计的舱门操作面板增强了人机功效,提高了作业的安全性和效率,减少了空乘人员的误操作和工作负荷。所设计的操作面板和区域控制面板不仅实现了整机舱门的集中监控管理与区域作动控制,还能作为人机交互设备,适用于大中型宽体飞机的客舱和货舱,应用前景十分广阔。

客机火灾条件下下降角度对舱内烟气温度分布规律的影响

为探究飞机客舱火灾紧急下降过程中,不同下降角度对火灾烟气运移的影响,运用FDS模拟软件建立波音737-400型飞机客舱全尺寸模型,分析7种飞行角度下客舱火源前、后部区域顶棚最高温度、客舱内部纵向温度场分布以及烟气蔓延过程。结果表明,飞机由巡航改为紧急下降状态会导致客舱内部出现烟囱效应,客舱不同区域烟气温度分布规律受下降角度影响表现不同,随着下降角度的增加,客舱前部烟气运移受阻明显,同一位置顶棚最高温度逐渐降低,温升速率与下降角度呈反比关系;客舱后部烟气在烟囱效应下迅速聚集、下沉,下降角度对其顶棚最高温度及温度分布的影响逐渐弱化。

民机客舱空调送风方式对CO_(2)传播及通风性能影响的数值模拟

利用计算流体力学方法构建A320经济舱7排座数值模型,并对CFD模型进行验证。对顶部送风、混合送风以及置换送风三种空调送风模式进行数值模拟,以CO_(2)作为污染物对比分析飞机客舱通风性能及排污效率。研究发现:顶部送风会使中间乘客吹风感较强,乘客垂直温差约为3K;混合送风的速度场和温度场分布均匀,热舒适性良好;置换送风模式下,乘客周围速度小于0.3m/s,存在温度分层现象,气流运动受到人体热羽流的影响显著。从排污效果看,置换送风会使乘客周围的CO_(2)积聚时间较长,呼吸区平均浓度高出约35%;顶部送风和混合送风的排污效率大小相近。相较于传统空调送风模式,置换送风的排污效率提升了约42.8%,适用于飞机通风结构的优化。

Analysis of volatile organic compounds emitted from aircraft carpets:comparison using headspace and dynamic chamber tests

Volatile organic compounds(VOCs) emitted from three types of carpets used in aircrafts were compared by using headspace and dynamic chamber tests. The headspace samples contained many compounds that were not detected in the dynamic chamber test; in addition, the dominant VOCs found by these two methods were different. The findings indicate that for highly sorptive materials such as carpets, headspace analysis may give inaccurate indication of actual VOC emissions, and it is necessary to conduct dynamic chamber tests over a certain period of time in order to identify the true emission characteristics. From the dynamic chamber tests, 2-ethyl-1-hexanol was the main VOC emitted from all three carpets. The study also examined the emission characteristics of aircraft carpets. In all experiments, total VOC(TVOC) concentration peaked within a few hours after the start of the experiment and was followed by rapid decay. The emission parameters of TVOC emitted by all three carpets were calculated and the simulated data matched the measured data well.

民用飞机座舱舒适性影响因素研究综述

随着客机技术的发展和生活水平的提升,飞机已逐渐成为主流的交通方式之一,座舱环境舒适性也逐渐受到重视。聚焦于民用飞机舱室舒适性影响因素,采用文献调研的方式对飞机舱室主要环境参数控制要求、飞机运营中的实测座舱环境参数及运营飞机中乘客机组舒适性主观评价进行研究分析。研究发现,针对座舱环境参数的标准之间存在较多不一致性,且现有标准未直接体现出飞机座舱驾乘舒适性;通过分析飞机实测参数与指标要求及主观评价值,发现座舱环境的整体评价为“较为满意”,距离“满意”仍有距离,即座舱环境仍有提升的空间和必要性;对于乘客,不同的问卷调查研究结果略有差异,但均显示噪声是影响乘客整体满意度的最不利因素,风速和光线的影响最小,气压、空气品质、温度仍有一定影响;对于机组,相对湿度是最不利的环境因素,其次为空气品质和噪声,但目前关注机组舒适性问题的研究较少。本文的研究成果能够为飞机舒适性优化及提升技术发展方向提供参考。

飞行器舱室内壁蛛网仿生薄膜声学超材料设计

飞行器舱室内部噪声对乘员及飞行操控和通信构成了显著威胁,薄膜声学超材料(MAM)在满足轻量化要求的同时具有出色的降噪性能,能够满足航空工业领域对降噪和飞行器重量的双重要求。受蛛网启发,本文通过结合膜、框和一组振子设计了一种仿生薄膜声学超材料。计算和试验结果表明,仿生模型的振子质量减少了19%,降噪带宽扩展了61%。此外,本文研究了三种设计参数(薄膜形状、振子位置和模型大小)对结构降噪性能的影响规律,并分析了其多级反共振模态。结果表明,圆形模型在降噪性能上优于两个方形模型。当振子位置在半径比为0.54时,可获得最佳的降噪性能。模型在尺寸减小时仍有较大的降噪效果,但当尺寸增大时有失效的可能。非固定框在2×2阵列模型中有助于形成反共振模态,而在3×3阵列模型中作用则相反。根据不同的频率需求调节设计参数,能够适配于飞行器内部复杂、多变的噪声环境。