共查询到19条相似文献,搜索用时 187 毫秒
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气体静压多孔质止推轴承静态特性的理论发展 总被引:2,自引:0,他引:2
多孔质材料被用来作空气静压轴承的节流器在过去已经广为报道了。多孔质材料节流器化传统的了流器具有一些显的优点,如设计和制造简单,很高的承载能力和刚度,更优越的尼特性以及体成。甚至更加复杂的几何结构如球轴承,空气静压丝杠也能够很容易获得,到目前为止,止推轴承尤其是圆板状的止推轴承是进行理论分析的最简化的几何模型,同时也是报道最多的。本首先介绍多孔质空气静压轴承的理论,接着着重介绍多孔质止推轴承的理论发展,最后,作讨论了关于多孔质介质的进一步研究的方向。 相似文献
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为了讨论小孔节流空气静压支承轴承的节流器尺寸,气膜厚度与供气压等轴承参数对轴承力学性能的影响。针对圆柱腔小孔节流静压支承止推轴承,首先进行了轴承间隙流场的数值仿真与分析,其中以小孔尺寸,气腔尺寸,供气压及气膜厚为设计变量,利用正交实验设计的基本原理构造正交表,通过对轴承间隙流场的数值计算进行采样以获取轴承的承载力与刚度;其次在设计变量范围内基于径向基神经网络模型建立承载力与刚度的分析数学模型,在该分析模型中全面考虑了各轴承参数的作用,同时考虑了轴承间隙的流场结构对力学性能的影响,得到的模型经过拟合校验以证明具有足够的精度;最后基于该分析模型讨论了小孔与气腔尺寸对轴承承载力与刚度的影响,为工程设计提供了参考。 相似文献
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为了提高孔质静压气体轴承的刚度,将负压腔引入多孔质静压气体止推轴承的设计中,运用有限元方法对真空预载型多孔质静压气体止推轴承进行数值分析,分析负压腔真空度、负压腔面积比S_a/S(负压腔横截面积与轴承横截面积比值)、多孔材料渗透率、供气压力等因素对轴承静态特性的影响。分析结果显示:负压腔中真空度的变化对轴承的刚度几乎没有影响;真空度的增大,改变了气膜的压力分布造成轴承承载能力在一定程度上的下降;在气膜间隙5~12μm之间,真空腔的引入使气膜刚度明显增加;当S_a/S≠0,气膜间隙8~10μm时,S_a/S值的变化对轴承承载能力的影响较刚度更大;在一定承载能力下,轴承刚度随负压腔面积比增大而增大,而气膜厚度随之逐渐减小。试制真空吸附型多孔质静压气体止推轴承,并对其承载能力、刚度进行试验,实验值和理论值有较好的一致性。 相似文献
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应用Fluent软件对小孔节流气体静压止推轴承进行了三维流场的模拟计算,分析了节流孔孔径、节流器工作面积、气源供气压力等因素对气体静压轴承性能的影响。结果表明:止推轴承的承载能力随着节流孔直径的增大而增大,在气膜间隙较小时,刚度随着节流孔孔径增大而减小,在气膜间隙较大时,刚度随着节流孔孔径的增大而增大;在保证加工精度的前提下,增大节流器工作面尺寸,以及在保证气源供气连续的前提下,增大气腔供气压力,都可以显著地改善止推轴承的静态性能。在自行研制的实验平台上进行气体静压实验,实验结果与数值模拟计算结果具有较好一致性,证明了将该数值计算方法的可行性。 相似文献
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传统固有孔节流静压气体止推轴承研究的理论基础均建立在节流孔直径远大于气膜间隙的前提下,为了探究与气膜间隙同一数量级的微孔节流器静压气体止推轴承的静态性能,建立微孔节流静压气体止推轴承模型,通过CFD软件进行三维仿真,分析不同气膜间隙、孔径、供气压力对轴承静态特性的影响,并与环面节流器静压气体止推轴承进行对比。结果表明:无论是微孔节流器还是环面节流器,在节流孔出口处均有压降出现,但微孔节流器相对于环面节流器在节流孔出口边缘处速度和压力变化较为平缓;随着气膜间隙的增大轴承承载力减小,随着微孔节流器孔径减小轴承刚度增大,相同孔径下供气压力越大轴承承载力和刚度越大。 相似文献
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多孔质气体静压径向轴承的Fluent仿真与实验研究 总被引:1,自引:0,他引:1
多孔质气体静压轴承相比传统的小孔节流轴承具有更高的承载能力,更好的稳定性及便于加工等优点。应用基于有限体积法的软件Fluent分析偏心率、多孔质材料渗透率、轴承长径比和平均气膜厚度等关键因素对多孔质径向轴承静态性能的影响,分析结果显示,在给定轴承平均气膜厚度的情况下,存在最佳的渗透率区间使得承载能力最大,增加轴承长径比和减小平均气膜厚度均可以提高多孔质径向轴承的承载能力及刚度,但需要根据加工装配工艺要求及实际工况选择合适的参数。设计制造中心供气新形式的多孔质径向轴承,通过仿真得到气膜间隙的压力分布及承载能力,并通过实验验证仿真结果的正确性。仿真和实验结果表明,该结构形式的多孔质径向轴承承载性能优良。 相似文献
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This paper introduces a simple “Rule of Thumb” (ROT) method to estimate the load capacity of foil air journal bearings, which are self-acting compliant-surface hydrodynamic bearings being considered for Oil-Free turbomachinery applications such as gas turbine engines. The ROT is based on first principles and data available in the literature and it relates bearing load capacity to the bearing size and speed through an empirically based load capacity coefficient, D. It is shown that load capacity is a linear function of bearing surface velocity and bearing projected area. Furthermore, it was found that the load capacity coefficient, D, is related to the design features of the bearing compliant members and operating conditions (speed and ambient temperature). Early bearing designs with basic or “first generation” compliant support elements have relatively low load capacity. More advanced bearings, in which the compliance of the support structure is tailored, have load capacities up to five times those of simpler designs. The ROT enables simplified load capacity estimation for foil air journal bearings and can guide development of new Oil-Free turbomachinery systems. 相似文献
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Hydrodynamic lubrication of porous journal bearings using a modified Brinkman-extended Darcy model 总被引:1,自引:0,他引:1
A numerical solution for the hydrodynamic lubrication of finite porous journal bearings considering the flexibility of the liner is introduced. The Brinkman-extended Darcy equations and the Stokes' equations are utilized to model the flow in the porous region and fluid film region, respectively. A stress jump boundary condition at the porous media/fluid film interface and effects of viscous shear are included into the lubrication analysis. Elrod's cavitation algorithm, which automatically predicts film rupture and reformation in the bearing, is implemented in the solution scheme. The present analysis predictions for pressure distributions, load carrying capacity, and friction factor are in good agreement with three different sets of experimental results available in the literature. Furthermore, the effects of dimensionless permeability parameter, and stress jump parameter on performance parameters such as load carrying capacity, side leakage, friction factor, and attitude angle, are presented and discussed. 相似文献
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Rotation effects on hybrid air journal bearings 总被引:1,自引:0,他引:1
Rotation effects of hybrid air journal bearings with multi-arrays of orifice feedings are investigated numerically. Porous air bearings are also solved for comparison. The results show that bearing load capacity W increases faster with eccentricity ratio than with rotation speed, i.e. bearing number Be. There are optimum orifice diameters, i.e. optimum feeding parameters λo, which give maximum load capacity W for orifice feeding; but for porous feeding, load capacity W increases with feeding parameters λp. It was found that the load capacity increases with feeding arrays of orifices and five rows of orifice feedings can approximate the operations of porous bearings very well. It was also found that load capacity W does not increase further when air supply pressure exceeds 5 atm because there is a critical pressure ratio through orifice (e.g. (Po/Ps)<0.53). 相似文献
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Florin Dimofte 《摩擦学汇刊》2013,56(2):364-372
To identify the potential advantages of the wave journal bearing, a three-wave journal bearing was compared to both a three-wave-groove bearing (a wave bearing with axial grooves that isolate each wave) and a three-lobe bearing. The lobe bearing's profile was selected to approximate the wave journal bearing's profile. The lubricant was assumed to be compressible (gas). The bearing number, A, was parameterized from 0.01 to 100, and the eccentricity ratio, ε, was varied from 0 to 0.4. Data at bearing numbers 0.1, 1, and 50, and eccentricity ratios of 0.1 and 0.4, were selected as representative of the bearing performance. The calculated load capacity and the critical mass are presented for the three bearings. The wave bearing shows a better load capacity than the other bearings at any applied load and running regime. However, at high bearing numbers the lubricant compressibility effect is predominant and all three analyzed bearings show similar load capacity. The critical masses of the wave-groove and lobe bearing are greater than the critical mass of the wave bearing if the applied load is small. For low and intermediate bearing numbers the wave-groove bearing is more stable than the other bearings especially at low wave's amplitude ratio. The lobe bearing is more stable than the other analyzed bearings at high bearing numbers or at large preload ratios. If the applied load increases, the wave bearing dynamic performance is competitive with both wave-groove and lobe bearings. In addition, at high bearing numbers, the wave bearing could run stably for any allocated rotor mass over a wide range of wave position angle. Three wave bearings are more sensitive to the direction of the applied load than the other bearings especially at low and intermediate bearing numbers. Therefore, a careful selection of the waves position angle has to be done to maximize the wave bearing performance. 相似文献
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Previous studies in this series have investigated analytically and experimentally the performance characteristics of nonrotating porous journal bearings. In this paper the effects of rotation are analyzed for operation at small eccentricity ratios and also for operation at very large speed parameters. Shaft rotation is found to have a generally beneficial effect on the flow-rate requirements and load carrying capacity. 相似文献
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An experimental investigation is made regarding conical bearing characteristics related to the introduction of grooves. Load capacities of three bearing types are compared, i.e., smooth bearings, bearings with radial grooves, and bearings with inclined grooves rotated in both directions. The obtained results indicate that the presence of grooves significantly affects conical bearing performance. It is concluded that for the maximum load capacity, a bearing with inclined grooves should be used with forward rotation, i.e., when the entry part of the groove advances ahead of the exit of the groove. 相似文献
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The study deals with the development of a hybrid search algorithm for efficient optimization of porous air bearings. Both the compressible Reynolds equation and Darcy's law are linearized and solved iteratively by a successive-over-relaxation method for modeling parallel-surface porous bearings. Three factors affecting the computational efficiency of the numerical model are highlighted and discussed. The hybrid optimization is performed by adopting genetic algorithm (GA) for initial search and accelerated by simplex method (SM) for refined solution. A simple and useful variable transformation is presented and used to convert the unconstrained SM to a constrained method. In this study, the hybrid search algorithm for a multi-variable design exhibits better efficiency compared with the search efficiency by using the SM. The proposed hybrid method also eliminates the need of several trials with random initial guesses to ensure high probability of global optimization. This study presents a new approach for optimizing the performance of porous air bearings and other tribological components. 相似文献
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Christopher Dellacorte 《摩擦学汇刊》2013,56(4):674-684
Gas foil bearings are a key technology in many commercial and emerging oil-free turbomachinery systems. These bearings are nonlinear and have been difficult to analytically model in terms of performance characteristics such as load capacity, power loss, stiffness, and damping. Previous investigations led to an empirically derived method, a rule-of-thumb, to estimate load capacity. This method has been a valuable tool in system development. The current article extends this concept to include rules for stiffness and damping coefficient estimation. It is expected that these rules will further accelerate the development and deployment of advanced oil-free machines operating on gas foil bearings. 相似文献