附录一 英文科技文献翻译
中国有几个主席英文原文：
Experimental investigation of lar surface textured parallel thrust bearings素蟹粉
Performance enhancements by lar surface texturing (LST) of parallel-thrust bearings is experimentally investigated. Test
results are compared with a theoretical model and good correlation is found over the relevant operating conditions. A compari-
son of the performance of unidirectional and bi-directional partial-LST bearings with that of a baline, untextured bearing is
prented showing the benefits of LST in terms of incread clearance and reduced friction.
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KEY WORDS: fluid film bearings, slider bearings, surface texturing
1. Introduction
The classical theory of hydrodynamic lubrication yields linear (Couette) velocity distribution with zero pressure gradients between smooth parallel surfaces under steady-state sliding. This results in an unstable hydrodynamic film that would collap under any external force acting normal to the surfaces. However, experience shows that stable lubricating films can develop between parallel sliding surfaces, generally
becau of some mechanism that relaxes one or more of the assumptions of the classical theory.
A stable fluid film with sufficient load-carrying capacity in parallel sliding surfaces can be obtained, for example, with macro or micro surface structure of different types. The include waviness [1] and protruding microasperities [2–4]. A good literature review on the subject can be found in Ref. [5]. More recently, lar surface texturing (LST) [6–8], as well as inlet roughening by longitudinal or transver grooves [9] were suggested to provide load capacity in parallel sliding. The inlet roughness concept of Tonder [9] is bas
ed on ‘‘effective clearance’’ reduction in the sliding
direction and in this respect it is identical to the par- tial-LST concept described in ref. [10] for generating hydrostatic effect in high-pressure mechanical als.想念一个人的心情
气象万千
Very recently Wang et al. [11] demonstrated experimentally a doubling of the load-carrying capacity for the surface- texture design by reactive ion etching of SiC parallel-thrust bearings sliding in water. The simple parallel thrust bearings are usually found in al-less pumps where the pumped fluid is ud as the lubricant for the bearings. Due to the parallel sliding their performance is poorer than more sophisticated tapered or stepped bearings. Brizmer et al. [12] demon-strated the potential of lar surface texturing in the form of regular micro-dimples for providing load-carrying capacity with parallel-thrust bearings. A model of a textured parallel slider was developed and the effect of surface texturing on load-carrying capacity
was analyzed. The optimum parameters of the dimples were found in order to obtain maximum load-carrying capacity. A micro-dimple ‘‘collective effect’’ was identi-
fied that is capable of generating substantial load-carrying capacity, approaching that of optimumconventional thrust bearings. The purpo of the prent paper is to investigate experimentally the validity of the model described in Ref. [12] by testing practical thrust bearings and comparing the performance of LST bearings with that of the theoretical predictions and with the performance of standard non-textured
bearings
2. Background
A cross ction of the basic model that was analyzed in Ref. [12] is shown in figure
1. A slider having a width B is partially textured over a portion Bp =αB of its width. The textured surface consists of multiple dimples with a diameter，一村一警depthand area density Sp. As a result of the hydrodynamic pressure generated by the dimples the sliding surfaces will be parated by a clearancedepending on the sliding velocity U, the fluid viscosity l and the external loadIt was found in Ref. [12] that an optimum ratio exists for the parameter that provides maximum dimensionless load-carrying capacity where L is
羊冲什么生肖the bearing length, and this optimum value is hp=1.25. It was further found in Ref. [12] that an optimum value exists for the textured portion a depending onthe bearing aspect ratio L/B. This behavior is shown in figure 2 for a bearing with L/B = 0.75 at various values of the area density Sp. As can be en in the range of Sp values from 0.18 to 0.72 the optimum a value varies from 0.7 to 0.55, respectively. It can also be en from figure 2 that for a < 0.85 no optimum value exists for Sp and the maximum load W increas with increasing Sp. Hence, the largest area density that can be practically obtained with the lar texturing is desired. It is also interesting to note from figure 2 the advantage of partial-LST (a < 1) over the full LST (a = 1) for bearing applications. At Sp= 0.5, for example, the load W at a = 0.6 is about three times higher than its value at a = 1. A full account of this behavior is given in Ref. [12].
