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To improve the load capacity and stability of gas foil journal bearings (GFJB), this paper aims to propose a novel GFJB with taper-grooved top foil.

A modified bump stiffness model is established considering rounding and friction. By considering the variation of clearance in the circumferential and axial direction, the static and dynamic characteristics of the novel bearing are calculated using the finite difference method, and perturbation method, respectively. The bearing performance under different groove parameters is studied and compared to the traditional bearings.

The results show that this novel GFJB can bring multi-extra local dynamic pressure and decrease the gas end leakage, which improves the static and dynamic properties. Moreover, as the increment of groove depth, the load capacity and direct stiffness are reinforced. There is an optimal groove width to maximize the load capacity, and the taper-groove is more beneficial to the improvement of bearing performance than other groove shapes. For the novel GFJB (Ng = 6, Hg = 10µm), the load capacity and direct stiffness increase by about 6.67 and 13.5 per cent, respectively. The stability threshold speed (STS) of a rotor supported by the novel bearings is also increased.

The performance of the presented novel GFJB is enhanced immensely compared to the traditional bearings, and the results are expected to be helpful to bearing designers, researchers and academicians concerned.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0307.

The method of making a ring‐like flexible valve seat element for an internal combustion engine of the poppet valve type which comprises providing a suitable frusto‐conical shaped blank having a counterbored aperture extending therethrough with the large end of said aperture which also forms the seat proper opening into the large end of the blank and an annular tapered groove converging towards its bottom in the large end of the blank in spaced relation with said counterbore and undercutting a portion of the blank radially inwardly of the groove, the outer side wall of said groove diverging toward the surface of the blank, contracting the portion of the blank externally of the groove to only partly close said groove, and subsequently machining the blank to the desired final shape.

ALTHOUGH the primary object of this article is to describe processes and plant used in the manufacture of cold drawn seamless steel tubing, it cannot be considered complete without some reference to previous work on the steel, by which it is converted from the solid rolled billet to the hollow bloom, which may be considered as the “raw material” for cold drawing.

A description of how oxygen pressure vessels for the prototype B.A.C./Sud Concorde are manufactured from seamless steel tubing produced by the Weldless works of Tubes Limited and an outline of the salient features of the Concorde's oxygen system for crew and passengers. On February 28, 1968—just fourteen months hence—the first prototype Concorde supersonic airliner (FIG. 1) will make its maiden flight from the Toulouse‐Blagnac airfield in France. Six months later the second prototype will make its first flight from British Aircraft Corporation's airfield at Filton, Bristol. In September 1969, and November 1969, respectively, two pre‐production aircraft will fly for the first time—these having a longer fuselage, higher gross weight, additional fuel capacity and higher payload capacity than the prototype aircraft. Apart from the fact that the pre‐production types will carry full flight test instrumentation, they will be fully representative of production Concordes—60 of which have already been ordered for service with thirteen leading world airlines.

Considers the development of the automatic cutting tool selection system. Examines how the advent of knowledge‐based expert systems and CAD popularity has enabled wider availability of manufacturing process information, and the knowledge requirements for specifying optimal cutting tools in manufacturing environments where the number of machining operations makes the problem complex. Concludes that an ACTS expert system module can offer possibilities of total design systems when combined with CADCAM.

The ink maker and printer are vitally concerned with the behaviour to be expected from a pigment in terms of its contribution to printing properties (such as rheology, bleeding, damping water incompatibility), print appearance (colour, lustre), and useful service life (fading, resistance to chemical attack). Although practical printing tests can properly demonstrate the ultimate utility of a pigment for an intended use, sufficient preliminary data can normally be assembled to suggest candidate pigments suitable for evaluation.

The correct sealing of antifriction bearings is just as important as correct lubrication, in fact one is almost useless without the other.

THIS article is representative of tube manufacturing practice in general, but mainly deals with the tube range of Accles & Pollock, Limited, and its application to aircraft.

This study aims to investigate the rarefaction effects on flow and thermal performances of an equivalent sand-grain roughness model for aerodynamic thrust bearing.

In this study, a model of gas lubrication thrust bearing was established by modifying the wall roughness and considering rarefaction effect. The flow and lubrication characteristics of gas film were discussed based on the equivalent sand roughness model and rarefaction effect.

The boundary slip and the surface roughness effect lead to a decrease in gas film pressure and temperature, with a maximum decrease of 39.2% and 8.4%, respectively. The vortex effect present in the gas film is closely linked to the gas film’s pressure. Slip flow decreases the vortex effect, and an increase in roughness results in the development of slip flow. The increase of roughness leads to a decrease for the static and thermal characteristics.

This work uses the rarefaction effect and the equivalent sand roughness model to investigate the lubrication characteristics of gas thrust bearing. The results help to guide the selection of the surface roughness of rotor and bearing, so as to fully control the rarefaction effect and make use of it.