共查询到20条相似文献,搜索用时 656 毫秒
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通过阐述轴流通风机失速和喘振的机理,并分析实际生产中轴流通风机失速和喘振的发生过程,最终给生产运行人员提出了处理该故障的方法. 相似文献
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用ANSYS软件研究轴流通风机叶轮的振动特性 总被引:3,自引:0,他引:3
用ANSYS软件对轴流通风机叶轮的振动特性进行了分析。建立了轴流通风机叶轮的有限元模型,计算出了叶轮的固有频率,振型。说明了用ANSYS软件在对轴流通风机叶轮的振动特性分析上是一种先进方法,也可以用于通风机的计算机辅助设计。 相似文献
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对某轴流通风机进行了有无外风筒的(开式)PIV实验。实验中观测并捕捉到了无外风筒时轴流通风机内的叶尖涡。而在有外风筒情况下,气体从轴向进入且流动平稳,两种情况流动差别较大。为认识轴流通风机内流机制提供了实验依据。 相似文献
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用有限元法分析轴流通风机叶片的振动特性 总被引:6,自引:1,他引:6
本文是采用有限元方法对轴流通风机叶片进行系统振动分析的实例,首先是建立轴流通风机叶的有限元模型,然后在此基础上,计算出叶的固有振频、振型及叶片共振时的局部大应力区位置等。据此提出有限元方法对轴流通风机叶片的振动特性进行分析是一种切这可行的较好方法。 相似文献
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矿用轴流通风机叶片三维几何模型反求重构 总被引:1,自引:0,他引:1
通风机叶片形状是影响通风机气动性能的关键因素,为了引进和吸收先进的矿用轴流通风机叶片设计技术,采用反求技术对其三维几何模型进行反求重构.首先,根据通风机叶片设计特点规划测量路径,应用三坐标测量机(CMM)对矿用轴流通风机叶片表面曲面进行测量,提取通风机叶片表面曲面的三维点云数据.然后,在反求软件UG中,利用最小二乘拟合曲线检查法对所提取的点云数据进行异常点的剔除,运用弦高-夹角综合法进行点云数据的精简.最后,采用非均匀有理B样条(NURBS)对各截面数据点进行曲线拟合,并使用通过曲线组生成曲面的方法重构了矿用轴流通风机叶片的三维几何模型,这对矿用轴流通风机计算流体力学模拟和叶片优化设计具有重要意义. 相似文献
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《流体机械》2016,(11):15-19
为研究导叶式混流泵的轴向力,建立了导叶式混流泵内全三维流道模型,基于非定常大涡模拟亚格子尺度模型与滑移网格技术,对不同工况下的混流泵进行了数值模拟和性能预测,并将非定常方法计算值、定常方法计算值、经验公式估计值与试验值进行比较分析。结果表明:非定常方法计算得到的叶轮轴向力变化规律与试验和经验公式计算得到的轴向力变化规律更接近;在设计工况附近,定常和非定常方法计算得到的混流泵叶轮轴向力的数值与试验值的相对误差均约为10%;在小流量及大流量工况下,定常方法的计算值与试验值的相对误差约为30%,非定常方法的计算值与试验值的相对误差在10%之内。因此,非定常模拟方法可以更准确地预测混流泵的轴向力。 相似文献
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Jianjun Feng Xingqi Luo Pengcheng Guo Guangkuan Wu 《Journal of Mechanical Science and Technology》2016,30(4):1603-1610
Rotor-stator interaction in axial pumps can produce pressure fluctuations and further vibrations even damage to the pump system in some extreme case. In this paper, the influence of tip clearance on pressure fluctuations in an axial flow water pump has been investigated by numerical method. Three-dimensional unsteady flow in the axial flow water pump has been simulated with different tip clearances between the impeller blade tip and the casing wall. In addition to monitoring pressure fluctuations at some typical points, a new method based on pressure statistics was proposed to determine pressure fluctuations at all grid nodes inside the whole pump. The comparison shows that the existence of impeller tip clearance magnifies the pressure fluctuations in the impeller region, from the hub to shroud. However, the effect on pressure fluctuation in the diffuser region is not evident. Furthermore, the tip clearance vortex has also been examined under different tip clearances. 相似文献
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A. Javadzadegan M. Esmaeili S. Majidi B. Fakhimghanbarzadeh 《Journal of Mechanical Science and Technology》2009,23(9):2456-2467
The unsteady flow of blood through stenosed artery, driven by an oscillatory pressure gradient, is studied. An appropriate
shape of the time-dependent stenoses which are overlapped in the realm of the formation of arterial narrowing is constructed
mathematically. A msathematical model is developed by treating blood as a non-Newtonian fluid characterized by the Oldroyd-B
and Cross models. A numerical scheme has been used to solve the unsteady nonlinear Navier-stokes equations in cylindrical
coordinate system governing flow, assuming axial symmetry under laminar flow condition so that the problem effectively becomes
two-dimensional. Finite difference technique was used to investigate the effects of parameters such as pulsatility, non-Newtonian
properties and the flow time on the velocity components, the rate of flow, and the wall shear stress through their graphical
representations quantitatively at the end of the paper in order to validate the applicability of the present improved mathematical
model under consideration. 相似文献
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Man Yeong Ha 《Journal of Mechanical Science and Technology》1992,6(1):49-57
In order to study the oscillating flow induced by a high intensity acoustic field, a computer code which employs the two-dimensional, unsteady mass and momentum conservation equations for laminar flow in spherical coordinates has been developed. The displacement amplitude of the incident sound wave is large compared to the characteristic length of particles, and the acoustic Reynolds number based on the particle diameter and the velocity amplitude of the oscillating flow is less than about 100. Numerical solutions of these equations give the velocity field, axial pressure gradient, shear stress and flow separation angle around the particle for acoustically oscillating flow as a function of acoustic Reynolds number and Strouhal number. The axial pressure gradient, shear stress and separation angle are proportional to the magnitude of oscillating flow at low frequency (~50Hz) and can be approximated by the quasi-steady analysis. The effects of flow oscillation increase with increasing frequency (~2000Hz) due to combined effects of curvature and flow acceleration, giving different values of axial pressure gradient, shear stress and separation angle for different frequencies of 500, 1000 and 2000 Hz. 相似文献
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Time-accurate numerical calculations were performed to investigate unsteady flow features in a low-speed axial compressor. The test compressor has axial skewed slots over the rotor tip region as casing treatment to improve the stall margin. The calculated data are in good agreement with the measured data. This paper reports the effect of casing treatment and flow unsteadiness on the rotor near stall by examining the flows in the smooth wall and casing treatment cases. The axial skewed slot can remove the blockage induced by the tip clearance leakage flow by removing and injecting the flow near the tip. However, for the casing treatment case, blockage is induced near the hub because the hub-corner stall is caused by a decrease in the axial momentum in this region. The tip leakage flow has inherent unsteadiness in the smooth wall case caused by the relatively large tip clearance, whereas the hub-corner stall has unsteadiness in the casing treatment case. The two types of unsteadiness have functions in inducing stall inception. Furthermore, axial slots of different sizes were tested to examine the effect of slot geometry on rotor flow stability. The change in flow structure related to the stall inception was subject to flow injection through the recirculation in the slots. 相似文献
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The unsteady fluid-dynamic forces, generated by a flexural motion in axial (laminar) flow, have been formulated based on a collocation finite-difference method for concentric configurations, in connection with the flow-induced vibration problem. Based on the numerical method, the governing equations of the unsteady flow, obtained from the appropriate Navier-Stokes and continuity equations, redcuced to a system of algebraic equations leading to a block-tridiagonal system. To obtain a solution of the system, the LU decomposition method is used considering the factorization scheme. This numerical method is capable of taking fully into account unsteady viscous effects and of predicting viscous forces rigorously rather than approximately, in contrast with existing theories. In order to validate the numerical approach, semi-analytical approaches have been developed for estimating the fluid-dynamic forces. The numerical results are compared to the analytical results and good agreement was found. The contribution of unsteady viscous damping forces to the overall unsteady forces is significant for low values of the oscillatory Reynolds number, expecially in very narrow annuli. 相似文献
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Norimasa Shiomi W. X. Cai A. Muraoka K. Kaneko T. Setoguchi 《Journal of Mechanical Science and Technology》2001,15(12):1860-1868
An experimental investigation was carried out to clarify unsteady flow fields with rotating stall cell, especially behavior
of stall cell, in a high specific-speed diagonal flow fan. As its specific-speed is very high for a diagonal flow fan, its
pressure-flow rate curve tends to indicate unstable characteristics caused by rotating stall similar to axial flow fan. Although
for an axial flow fan many researchers have investigated such the flow field, for a diagonal flow fan little study has been
done. In this study, velocity fields at rotor inlet in a high specific-speed diagonal flow fan were measured by use of a single
slant hot-wire probe. These data were processed by using the ““Double Phase-Locked Averaging“ (DPLA) technique, i. e. phases
of both the rotor blade and the stall cell were taken into account. The behaviors of stall cell at rotor inlet were visualized
for the meridional, tangential and radial velocity. 相似文献
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The effects on the interlaminar stresses of an unsteady aerodynamic loading on a laminated composite strip are studied. A stress-function-based variational approach and the finite difference method are used to determine the interlaminar stresses in a multilayered strip subjected to arbitrary combinations of axial extension, bending and the unsteady aerodynamic loading of supersonic fluid flow over the upper surface of laminated composite strips. Symmetric four-layer, cross-ply and angle-ply laminates are considered in detail. Some numerical solutions by using a personal computer are obtained. The present results show that the unsteady aerodynamic loading has significant effects on the interlaminar stresses near the free-edge regions. 相似文献
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A small amplitude perturbation analysis has been carried out to determine the rotordynamic characteristics of multilobe hybrid bearings with short axial and circumferential sills. Unsteady state recess flow continuity equation has been written for orifice compensated bearing in terms of dynamic recess pressures by perturbing steady state flow equation. Dynamic recess pressures are evaluated by solving unsteady recess flow continuity equations to determine the dynamic load capacity of the bearing. Stiffness and damping coefficients of the bearing are determined from the dynamic load capacity of the bearing. Results of dynamic characteristics of three lobe and four lobe hybrid bearings are presented for various offset factors, speed, concentric pressure and eccentricity ratios. Multilobe hybrid bearings with offset factors more than one are found to exhibit better dynamic behaviour than circular hybrid bearings. 相似文献