基于机舱环境背景下的冲击射流与湍流热对流的实验研究

发布时间：2019-05-20 00:42

【摘要】：122客机座舱是一个封闭、狭小、人员密集的特殊微环境,影响舱内气流分布的主要因素有:送风系统通过风口流出的气流、乘客口鼻呼吸产生的气流、由乘客和飞机本身散热引起的热浮力驱动的气流以及由客机座舱内复杂的几何结构引起的分离流。送风口流出的气流和乘客口鼻呼吸的气流与自由射流类似,在遇到座椅和其它设备时形成了冲击效应,而由乘客自身散热引起的热浮力驱动的气流运动形成了湍流热对流。因此,客机座舱内的气流是一种包含冲击射流和湍流热对流的复杂流动。对客机座舱内的空气流动进行研究,是创造一个安全、舒适、健康的客机座舱环境的必要前提。本文采用热线测速技术和粒子图像测速技术,分别对基于机舱环境背景下的冲击射流和湍流热对流进行实验研究,作为实际客机座舱内气流运动研究的基础。采用热线测速技术对冲击湍射流的流场特性进行了实验研究。利用IFA300恒温热线测速仪、标准X型双丝热线探针和边界层X型双丝热线探针,以高于湍流最小时间尺度的分辨率,精细测量了冲击湍射流自由射流区的轴向、径向速度分量的径向分布和壁面射流区径向、轴向速度分量的轴向分布,得到了平均速度、湍流强度、雷诺剪切应力、高阶矩、能谱、耗散谱以及空间特征尺度在自由射流区和壁面射流区的分布。运用小波变换和希尔伯特—黄变换分别对测得的冲击湍射流速度场进行了多尺度(多模态)分析,描述了不同尺度(模态)能谱的湍流能量级串过程,基于此并对这两种分解方法进行了比较,发现希尔伯特—黄变换能够更加准确地刻画出不同尺度(模态)结构在湍动能量传输过程中的变化与作用。最后,通过希尔伯特—黄变换方法获得了冲击湍射流自由射流区和壁面射流区不同模态结构的平均频率与流动结构在不同平均频率下的能量密度分布。采用粒子图像测速技术,对等温工况与加热工况下的暖体假人模型的呼吸流场进行了实验研究。利用周期相位平均方法对两种工况下测得的周期变化的湍流场进行了湍流量统计,得到了呼吸过程中不同相位下的相平均速度、湍流强度和涡量的时空分布演化特征。采用本征正交分解方法将呼吸瞬态湍流场分解为平均流场、拟序流场、过渡流场和湍流流场四部分,研究了四个分流场的各自特点、演变规律以及循环变动特性。运用空间互相关技术,对两种工况不同相位下的雷诺应力与平均速度变形率的空间相位关系变化进行了研究。
[Abstract]:The cockpit of 122 passenger plane is a special microenvironment with closed, narrow and dense personnel. The main factors affecting the distribution of air flow in the cabin are: the air flow from the air supply system through the tuyere, and the air flow generated by passengers' mouth and nose breathing. The flow of air driven by thermal buoyancy caused by the heat dissipation of passengers and aircraft itself and the separated flow caused by the complex geometric structure in the cockpit of an airliner. The air flow out of the tuyere is similar to that of the free jet, which forms an impact effect when the seat and other equipment are encountered, while the air flow driven by the thermal buoyancy caused by the heat dissipation of the passenger itself forms a turbulent thermal convection. Therefore, the air flow in the cockpit of an airliner is a kind of complex flow which includes impinging jet and turbulent thermal convection. The study of air flow in the cockpit of an airliner is a necessary prerequisite for creating a safe, comfortable and healthy cockpit environment. In this paper, hot wire velocimeter technology and particle image velocimeter technology are used to study the impinging jet and turbulent thermal convolution based on the background of cabin environment, which is the basis of the study of airflow motion in the cockpit of an actual passenger plane. The flow field characteristics of impingement turbulent jet were studied by hot wire velocimeter technique. By using IFA300 constant temperature hot wire velocimeter, standard X double wire hot wire probe and boundary layer X double wire hot wire probe, the axial direction of free jet zone of impingement turbulent jet is measured in detail at a resolution higher than the minimum time scale of turbulence. The radial distribution of the radial velocity component and the axial distribution of the radial and axial velocity components in the wall jet region are obtained, and the average velocity, turbulence intensity, Reynolds shear stress, high order moment and energy spectrum are obtained. The distribution of dissipation spectrum and spatial characteristic scale in free jet region and wall jet region. The multi-scale (multimodal) analysis of the measured velocity field of impinging turbulent jet is carried out by using wavelet transform and Hilbert-Huang transform, respectively, and the turbulent energy cascade process of different scale (modal) energy spectrum is described. Based on this and the comparison of the two decomposition methods, it is found that the Hilbert-Huang transform can more accurately depict the changes and functions of different scale (modal) structures in the process of turbulent energy transfer. Finally, the average frequency of different modal structures in the free jet region and the wall jet region and the energy density distribution of the flow structure at different average frequencies are obtained by means of Hilbert-Huang transformation method. The respiratory flow field of warm body dummy model under constant temperature and heating conditions was studied by using particle image velocimeter technique. The periodic phase average method is used to calculate the turbulent flow field with periodic variation under two working conditions, and the temporal and spatial distribution and evolution characteristics of phase average velocity, turbulence intensity and vorticity under different phases are obtained. The intrinsic orthogonal decomposition method is used to decompose the respiratory transient turbulent field into four parts: average flow field, quasi-ordered flow field, transitional flow field and turbulent flow field. The characteristics, evolution law and cyclic variation characteristics of the four separate flow fields are studied. The spatial phase relationship between Reynolds stress and average velocity deformation rate under different phases is studied by using spatial cross-correlation technique.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：O357.5;O358

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