基于逾渗理论的静密封建模方法与泄漏机理研究
发布时间：2018-08-22 07:26
【摘要】：静密封在密封结构中占有重要地位,被广泛应用在航空、航天、车辆、船舶等机电产品中。长期以来,由于静密封失效导致的特种车辆等机电产品中漏油、漏水、漏气等“三漏”问题一直是困扰企业的难题,已经成为保障产品可靠服役的关键因素之一。本文针对静密封失效问题,对金属平面静密封的机理及相关理论、方法进行了深入研究。本文的主要研究工作如下:(1)分析了国内外在静密封及其相关领域上理论、技术的研究进展,指出了目前研究成果存在的问题与不足,并在此基础上给出了论文的研究框架和研究内容。(2)以特种车辆为例分析了静密封失效的类型、原因和后果等,在此基础上提出了静密封的基本模型,并对静密封界面进行了逾渗系统建模。(3)为了研究金属表面在各个尺度的接触行为,提出了基于确定性模型的粗糙表面各尺度接触行为分析方法,首先通过设备实测得到加工表面的形貌数据,其次通过小波滤波器对工程表面进行多尺度分解,最后采用有限元方法建立各个尺度的确定性接触模型,研究了实测表面各尺度分量上无量纲接触面积随无量纲法向压力的变化规律,发现不同伪周期的表面分量具有不同的变化规律;同时研究了材料属性和加载卸载过程对接触行为的影响,最后通过求解高斯表面的接触过程验证了本文确定性模型和所发现规律的有效性。(4)针对确定性接触模型带来大规模计算问题,基于FEAP和PETSc研究了预条件Krylov子空间求解方法,通过采用不同的预条件子和Krylov子空间法求解大小变化的有限元接触问题,从求解时间、并行性、存储空间和稳定性方面对不同组合的预条件Krylov子空间进行了研究,得到了求解此类问题较理想的方法。(5)在对密封界面进行离散和近似的基础上,提出了一种基于栅格渗漏模型的静密封界面渗漏状态预测模型。首先给出了栅格渗漏模型的构建方法,在此基础上通过大量数值实验对密封-渗漏状态演变特性进行了分析,进而建立了静密封界面状态演变曲线的数学模型,发现渗漏发生的概率在与系统相关的阈值附近呈现急转变化的规律,同时研究表明静密封界面的接触面积、表面纹理方向等对密封界面的状态演变特性有显著影响。(6)通过求解1000个随机网格上形成渗漏通道的Navier-Stokes方程,并结合所形成渗漏通道的结构特征,研究了在低雷诺数情况下流体介质流经密封界面的输运特性和尺度效应。数值试验表明,密封界面上平均渗漏率在次临界区和超临界区呈现出不同的变化规律,并且急剧增大的区间滞后于渗漏概率急转增大的区间;远离逾渗阈值处的和逾渗阈值处的渗漏率的变化规律存在明显的差异,逾渗阈值处的平均渗漏率与逾渗系统尺寸呈幂律关系,并与远离逾渗阈值处相比有着更陡的下降趋势。(7)设计并开发了综合密封实验台和多通道垫圈式轴力测量设备,结合实际应用设计静密封实验,对静密封性能与规律进行了实验研究,对论文所得的结论进行了验证。
[Abstract]:Static seal plays an important role in sealing structure and is widely used in aerospace, vehicles, ships and other mechanical and electrical products. One of the key factors is the failure of static seal. In this paper, the mechanism and related theories and methods of metal plane static seal are studied deeply. The main research work of this paper is as follows: (1) The theory and technology research progress in static seal and related fields at home and abroad are analyzed, and the existing problems and shortcomings of current research results are pointed out. On this basis, the research framework and contents of this paper are given. (2) Taking special vehicles as an example, the types, causes and consequences of static seal failure are analyzed. On this basis, the basic model of static seal is put forward, and the percolation system model of static seal interface is established. (3) In order to study the contact behavior of metal surface at various scales, the contact behavior of metal surface is proposed. The contact behavior analysis method of rough surface at different scales based on deterministic model is proposed. Firstly, the shape data of machined surface are measured by equipment, and then the engineering surface is decomposed by wavelet filter. Finally, the deterministic contact model of each scale is established by finite element method. The variations of the dimensionless contact area with the dimensionless normal pressure on the components show that the surface components of different pseudo-periods have different variations. The effects of material properties and loading and unloading processes on the contact behavior are also studied. Finally, the deterministic model and the discovered rules are verified by solving the contact process of the Gaussian surface. (4) Aiming at the large-scale computational problems caused by deterministic contact model, the preconditioned Krylov subspace method is studied based on FEAP and PETSc. By using different preconditioners and Krylov subspace methods, the finite element contact problems with varying sizes are solved. The time, parallelism, storage space and stability of the solution are discussed. The preconditioned Krylov subspace with the same combination is studied and an ideal method for solving this problem is obtained. (5) Based on the discretization and approximation of the sealing interface, a prediction model for the leakage state of the static sealing interface is proposed based on the grid leakage model. Through a large number of numerical experiments, the evolution characteristics of seal-leakage state are analyzed, and then the mathematical model of the evolution curve of the static seal interface state is established. It is found that the probability of leakage occurs changes rapidly near the threshold value related to the system. (6) By solving Navier-Stokes equations of seepage passages on 1000 random grids and combining with the structural characteristics of seepage passages, the transport characteristics and scale effects of fluid flow through the sealing interface at low Reynolds number are studied. The upper average seepage rate shows different variation regularity in the subcritical and supercritical regions, and the rapidly increasing interval lags behind the rapidly increasing interval of the seepage probability; the variation regularity of the seepage rate at the distance from the percolation threshold and at the percolation threshold is obviously different, and the average seepage rate at the percolation threshold is in accordance with the size of the percolation system. (7) Designed and developed a comprehensive seal test bench and multi-channel gasket axial force measuring equipment, combined with practical application design static seal experiment, carried out experimental research on static seal performance and law, and verified the conclusions of the paper.
【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB42
本文编号：2196397
[Abstract]:Static seal plays an important role in sealing structure and is widely used in aerospace, vehicles, ships and other mechanical and electrical products. One of the key factors is the failure of static seal. In this paper, the mechanism and related theories and methods of metal plane static seal are studied deeply. The main research work of this paper is as follows: (1) The theory and technology research progress in static seal and related fields at home and abroad are analyzed, and the existing problems and shortcomings of current research results are pointed out. On this basis, the research framework and contents of this paper are given. (2) Taking special vehicles as an example, the types, causes and consequences of static seal failure are analyzed. On this basis, the basic model of static seal is put forward, and the percolation system model of static seal interface is established. (3) In order to study the contact behavior of metal surface at various scales, the contact behavior of metal surface is proposed. The contact behavior analysis method of rough surface at different scales based on deterministic model is proposed. Firstly, the shape data of machined surface are measured by equipment, and then the engineering surface is decomposed by wavelet filter. Finally, the deterministic contact model of each scale is established by finite element method. The variations of the dimensionless contact area with the dimensionless normal pressure on the components show that the surface components of different pseudo-periods have different variations. The effects of material properties and loading and unloading processes on the contact behavior are also studied. Finally, the deterministic model and the discovered rules are verified by solving the contact process of the Gaussian surface. (4) Aiming at the large-scale computational problems caused by deterministic contact model, the preconditioned Krylov subspace method is studied based on FEAP and PETSc. By using different preconditioners and Krylov subspace methods, the finite element contact problems with varying sizes are solved. The time, parallelism, storage space and stability of the solution are discussed. The preconditioned Krylov subspace with the same combination is studied and an ideal method for solving this problem is obtained. (5) Based on the discretization and approximation of the sealing interface, a prediction model for the leakage state of the static sealing interface is proposed based on the grid leakage model. Through a large number of numerical experiments, the evolution characteristics of seal-leakage state are analyzed, and then the mathematical model of the evolution curve of the static seal interface state is established. It is found that the probability of leakage occurs changes rapidly near the threshold value related to the system. (6) By solving Navier-Stokes equations of seepage passages on 1000 random grids and combining with the structural characteristics of seepage passages, the transport characteristics and scale effects of fluid flow through the sealing interface at low Reynolds number are studied. The upper average seepage rate shows different variation regularity in the subcritical and supercritical regions, and the rapidly increasing interval lags behind the rapidly increasing interval of the seepage probability; the variation regularity of the seepage rate at the distance from the percolation threshold and at the percolation threshold is obviously different, and the average seepage rate at the percolation threshold is in accordance with the size of the percolation system. (7) Designed and developed a comprehensive seal test bench and multi-channel gasket axial force measuring equipment, combined with practical application design static seal experiment, carried out experimental research on static seal performance and law, and verified the conclusions of the paper.
【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB42
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