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The effects of journal misalignment on the transient flow of a finite grooved journal bearing are presented in this study.
A new 3D computational fluid dynamics (CFD) analysis method is applied. Also, the quasi-coupling calculation of transient
fluid dynamics of oil film in journal bearing and rotor dynamics is considered in the analysis. Based on the structured mesh,
a new approach for mesh movement is proposed to update the mesh volume when the journal moves during the fluid dynamics simulation
of an oil film. Existing dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in journal bearings.
The movement of the journal is obtained by solving the moving equations of the rotor-bearing system with the calculated film
pressure as the boundary condition of the load. The data exchange between fluid dynamics and rotor dynamics is realized by
data files. Results obtained from the CFD model were consistent with previous experimental results on misaligned journal bearings.
Film pressure, oil film force, friction torque, misalignment moment and attitude angle were calculated and compared for misaligned
and aligned journal bearings. The results indicate that bearing performances are greatly affected by misalignment which is
caused by unbalanced excitation, and the CFD method based on the fluid-structure interaction (FSI) technique can effectively
predict the transient flow field of a misaligned journal bearing in a rotor-bearing system. 相似文献
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《天津大学学报(英文版)》2017,(5)
Channel engineering stability with underground goafs is a complex three-dimensional problem, especially when considering channel leakage, and is influenced by a number of processes, such as seepage, fluid structure interaction(FSI), modeling, and selection of geological mechanical parameters. In this study, stability finite element analysis by one-way FSI was performed by establishing an integrated 3D engineering geological model. The extended Fourier amplitude sensitivity test was used to quantitatively assess the first-order and total sensitivities of the engineering model to critical geological mechanical parameters. Results illustrate that the channel engineering deformation is under a reasonable range and the elastic modulus is the highest total sensitivity parameter for the channel tilt and curvature at 0.7395 and 0.7525, respectively. Moreover, the most observable coupling effects for the curvature and horizontal strain are cohesion(0.1933)and density(0.7410), respectively. 相似文献
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Recently, the finite element method (FEM) has been commonly applied in the engineering analysis of rotor dynamics. Gyroscopic moments, rotary inertia, transverse shear deformation and gravity can be included in computational models of rotor-bearing systems. In this paper, a finite element model and its solution method are presented for the calculation of the dynamics of dual rotor systems. A typical structure with two rotor shafts is discussed and the procedure for obtaining the coupling motion equations of the subsystems is illustrated. A computer program is developed to solve critical speeds and to simulate the transient motion. The influence of gyroscopic moments on co-rotation and counter-rotation is analyzed, and the effect of the speed ratio on critical speed is studied. The dynamic characteristics under different conditions of increasing speed during start-up are demonstrated by comparison with transient nodal displacements. The presented model provides a complete foundation for further investigation of the dynamics of dual rotor systems. 相似文献
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路径规划算法研究是自动泊车系统中最常见的问题之一。为解决平行泊车场景下,车辆泊车入位较难的问题,采用反向推导法,理论分析泊车过程并推导了路径规划函数公式,在确定泊车起点后,能够安全引导车辆进入泊车位。首先建立车辆模型,在确定碰撞约束和最优目标函数后,推导了车辆三阶段单向行驶泊车路径;然后针对单向泊车路径规划中要求车位长度较长的问题,提出四阶段行驶路径规划方法;最后,根据实际车辆及车位信息,利用Matlab软件与实验车平台,分别验证了该路径规划方法的有效性。实验结果表明,采用双向四阶段泊车方式相比单向三阶段泊车方式,对车位长度的要求缩短了0.26m。 相似文献
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高校课堂教学模式的选择 总被引：6，自引：0，他引：6
潘成云 《扬州大学学报(高教研究版)》2001,5(4):72-73
“单向灌输式”与“双向互动式”是两种不同的教学模式，它们具有各自的特点。长期以来我国高校课堂教学以“单向灌输式”为主。随着社会经济环境的变化，“双向互动式”必将成为课堂教学模式的选择之一。 相似文献
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Dependent on automatically generated unstructured grids, a comprehensive computational fluid dynamics(CFD)numerical simulation is performed to analyze the influence of nozzle geometry on the internal flow characteristics of a multi-hole diesel injector with the multi-phase flow model based on Eulerian multi-fluid method.The diesel components in nozzle are considered as two continuous phases, diesel liquid and diesel vapor respectively.Considering that both of them are fully coupled and interpenetrated, sepa... 相似文献
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In this paper, dynamic analyses of the swash plate vibration and pressure pulsation of an aircraft piston pump based on fluid-structure interactions (FSIs) are presented. Models of the swash plate piston pumps with three FSIs (named full FSIs and non FSI) are given. The simulation results of the discharge pressures at different rotation speeds in the synthesized pump model and experiments show good agreement. The numerical simulation results of the forces on the swash plate and the flow rate of the outlet chamber are presented and compared. The results of the two models show that the discharge pressure pulsation mostly depends on the kinematic relations of the piston slipper-shoe units (FSI-1), and is almost isolated from the swash plate vibration. The full FSIs simulation shows that the swash plate vibration is strongly influenced by the pressure pulsation through the control actuator mechanism (FSI-2) and the control valve mechanism (FSI-3), but the non FSI model does not show the same result. The full FSIs model is much more accurate in predicting the vibration of the swash plate and the pulsation of the discharge pressure than the non FSI model. 相似文献
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提出了一种无线传感器网络中基于蚁群算法的单向链路路由算法,该算法采用单向链路和双向链路相结合的方法,寻找源节点到目的节点的最优路径。仿真结果表明,该算法能够选择参数性能好的路径,最优路径上的总时延远远小于只支持双向链路的传统蚁群算法,而且最优路径的收敛速度明显加快,由此节省了无线传感器网络中的能耗。 相似文献
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A numerical simulation of the interaction between laminar flow with low Reynolds number and a highly flexible elastic sheet is presented. The mathematical model for the simulation includes a three-dimensional finitevolume based fluid solver for incompressible viscous flow and a combined finite-discrete element method for the three-dimensional deformation of solid. An immersed boundary method is used to couple the simulation of fluid and solid. It is implemented through a set of immersed boundary points scattered on the solid surface. These points provide a deformable solid wall boundary for the fluid by adding body force to Navier-Stokes equations. The force from the fluid is also obtained for each point and then applied on the boundary nodes of the solid. The vortex-induced vibration of the highly flexible elastic sheet is simulated with the established mathematical model. The simulated results for both swing pattern and oscillation frequency of the elastic sheet in low Reynolds number flow agree well with experimental data. 相似文献
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In this paper,an equation system of electrohydrodynamics(EHD)based onthe fluid motion equations is discussed.Emphasis is put on the effects of electrical forceand surface tension upon the fluid motion.The Marker and Cell method is used to set up acomputational simulation program of electrically driven motion of fluid.With the help ofthe program,a cylindrical fluid under the influences of electrical field and surface tensionhas been calculated.The result is in good agreement with the experimental observation. 相似文献
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In this study a new dynamic model of a rotor system is established based on the Hamilton principle and the finite element method (FEM). We analyze the dynamic behavior of the rotor system with the coupled effects of the nonlinear oil film force, the nonlinear seal force, and the mass eccentricity of the disk. The equations of the motion are solved effectively using the fourth order Runge-Kutta method in MATLAB. The dynamic behavior of the system is illustrated by bifurcation diagrams, largest Lyapunov exponents, phase trajectory diagrams, and Poincaré maps. The numerical results show that the rotational speed of the rotor, the pressure drop in the seal, the seal length, the seal clearance, and the mass eccentricity of the disk are the key parameters that significantly affect the dynamic characteristics of the rotor system. The motion of the rotor system exhibits complex types of periodic, quasi-periodic, double-periodic, multi-periodic, and chaotic vibrations. This analysis can be used to guide the design of seal parameters and to diagnose the vibration of rotor/bearing/seal systems. 相似文献
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根据液压传动课程的教学内容和特点,通过实例说明流体动力学软件Fluent在教学中的应用,直观展示了流体在元件内部的流动情况,速度、压力的定量分布规律,依此分析结构对流动特性及元件性能的影响。仿真教学有助于学生掌握抽象的流体力学理论,加深对元件工作原理的理解及仿真设计方法的使用,拓展了现有的教学方式,加强了教学与工程应用之间的有机结合。 相似文献
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分析了大型转子绕线机的运动模型,采用最小偏差准则,给出了实现绕线机飞叉轴和水平轴运动控制的直线插补算法。并进一步通过仿真和实际绕线实验验证该算法的有效性。在仿真实验中,采用的最小偏差直线插补算法具有较好的绕线精度;在RW400大型绕线机实际绕线测试实验中,大型电机转子绕线间距均匀,排列紧密,单圈误差小于0.1%。实验结果表明,最小偏差直线插补算法能够较好地用于大型电机转子绕线机插补运动控制。 相似文献
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LIU Xin 《浙江大学学报(A卷英文版)》2006,7(6):1061-1067
INTRODUCTION Meshfree methods are increasingly becoming popular as they are effective for dealing with com-putational mechanics problems including both solid and fluid problems. Most of various approaches proposed in (Liu, 2002) are based on Galerkin form (weak form) which need background meshes for numerical integrations, and are actually not truly meshfree methods. Other approaches are based on collocation form (strong form), such as finite point method (FPM) (Onate et al., 1996), ra… 相似文献
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卢义玉 《重庆大学学报(英文版)》2003,2(1)
~~00002RKRSr= (6) If 0tKt=, Eqs. (2),(3) and (4) change into the following equation that is applied to simulations using the MathCAD software. ddd(,,)dd1dxyygxyzzttt=== (7) where 11251(,,)()(1)gxyzABCyxaaaa=++-+, 2132131145678222124531678831(1),23(1)[(1sin],[3cos()] AyyByxxyxzCxyxyxyxzggaaaaaaaaaaaaagaaaa-------=--=++---+=+-- (8) 5g00pK6g0p… 相似文献