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This paper aims to study the bearing performance with different cone angle errors, to study the effect law of manufacturing taper error on the properties of gas foil conical bearing (GFCB).

For the GFCB supported by separated bump foil strips, a nonlinear structure stiffness model considering Coulomb friction and arch characteristics was proposed. The finite element method and finite difference method were used to solve the Reynolds equation and the film thickness equation by coupling, and the properties of the GFCB were obtained. The effect of foil and bearing structure parameters on the static and dynamic performance under different taper error cases was analyzed. Moreover, a test on the air compressor supported by GFCBs was conducted to verify the practicability.

The taper error has a largely adverse effect on the load capacity of GFCB. When the taper error is −0.03°, the radial load capacity Fr and axial load capacity Fz decrease by 37.5 and 58.3%, respectively. The taper error decreases the direct stiffness and cross-coupled damping of GFCB, which will weaken the bearing stability. Moreover, the performance of GFCB is closely related to the foil and bearing parameters.

The taper error adversely affects the static and dynamic characteristics of GFCB, which should be concerned by bearing designers, researchers and academicians.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2020-0089/

The purpose of this paper is to study the characteristics of gas foil conical bearings (GFCBs) considering the misalignment, the static and dynamic performances with different misalignment cases were studied.

A test rig on the air compressor supported by GFCBs has been developed to measure the practicability. A nonlinear bump stiffness model and one-dimensional beam top foil stiffness model were used as a basis for the calculation of static and dynamic performance. The finite element method and finite difference method are adopted to solve the Reynolds equation and the film thickness equation coupled, in which different misalignment cases were considered by changing the film thickness.

The supporting performance of GFCB is excellent, and the film clearance plays a critical role. The misalignment effects depend on the assembled angle and the misalignment angle. The load capacity, friction torque, temperature of GFCB decrease when the misalignment assembled angle is between 120° and 240°, while the dynamic bearing stability is improved. The static and dynamic performances show the opposite law for the other assembled angles, and the misalignment effect is more dramatic when there is a larger misalignment angle. Moreover, the bearing and running parameters largely affect the bearing performance.

The present study focuses on the static and dynamic characteristics of GFCB and investigates the effects of misalignment on the bearing performance.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0117

The purpose of this paper is to study the effect law of roundness error on the properties of gas foil conical bearing (GFCB), and the performance of bearings with different non-circular sleeve shapes are calculated.

For the bump-type GFCB, the nonlinear bump foil stiffness model and 1-D beam top foil stiffness model are built. On this basis, the finite element method and finite difference method are used to solve the Reynolds equation and the film thickness equation coupled, and the static and dynamic properties of GFCB are calculated. The effect law of sleeve roundness error on the static performance under different conditions is obtained. Moreover, the dynamic stiffness and damping characteristics under different errors are also studied.

The roundness error will decrease the load capacity and friction torque of GFCB, and increase the attitude angle. The error effect is more dramatic when there is larger eccentric, small nominal clearance, larger error value and more error lobes, and the static performance exhibits a periodic change in the circumferential direction. The roundness error can also decrease the direct stiffness and cross-coupled damping of GFCB, while the cross-coupled stiffness increases largely, which will reduce the bearing stability.

The roundness error adversely affects the static and dynamic characteristics of GFCB, which should be concerned by bearing designers, researchers and academicians.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0019/

The purpose of this paper is to investigate dynamic characteristics of opposed-conical gas-dynamic bearings considering five degree-of-freedom motion, including translation and tilt.

The steady-state Reynolds equation and perturbed Reynolds equations are solved on the surface of conical bearings, and both stiffness and damping coefficients are calculated. A formula for quickly calculating critical mass is deduced to discriminate the stability of the rotor considering the five degree-of-freedom motion.

Results show that the stability of the rotor is mainly determined by translation rather than tilt. The formula of critical mass is validated by comparing the results with traditional Routh–Hurwitz criterion.

The formula proposed in this paper greatly simplifies the solution of critical mass, which facilitates the rotor stability design. It is applicable for opposed-conical bearings, opposed-hemispherical bearings and spherical bearings. The results provide theoretical guidance for the design of gas-dynamic bearings.

This paper gives a review of the finite element techniques (FE) applied in the analysis and design of machine elements; bolts and screws, belts and chains, springs and dampers, brakes, gears, bearings, gaskets and seals are handled. The range of applications of finite elements on these subjects is extremely wide and cannot be presented in a single paper; therefore the aim of this paper is to give FE researchers/users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An Appendix included at the end of the paper presents a bibliography on finite element applications in the analysis/design of machine elements for 1977‐1997.

TO say that the Twenty‐fourth S.B.A.C. Show was an unqualified success is perhaps to gild the lily. True there were disappointments— the delay which kept the TSR‐2 on the ground until well after the Show being one—but on the whole the British industry was well pleased with Farnborough week and if future sales could be related to the number of visitors then the order books would be full for many years to come. The total attendance at the Show was well over 400,000—this figure including just under 300,000 members of the public who paid to enter on the last three days of the Show. Those who argued in favour of allowing a two‐year interval between the 1962 Show and this one seem to be fully vindicated, for these attendance figures are an all‐time record. This augurs well for the future for it would appear that potential customers from overseas are still anxious to attend the Farnborough Show, while the public attendance figures indicate that Britain is still air‐minded to a very healthy degree. It is difficult to pick out any one feature or even one aircraft as being really outstanding at Farnborough, but certainly the range of rear‐engined civil jets (HS. 125, BAC One‐Eleven, Trident and VCIQ) served as a re‐minder that British aeronautical engineering prowess is without parallel, while the number of rotorcraft to be seen in the flying display empha‐sized the growing importance of the helicopter in both civil and military operations. As far as the value of Farnborough is concerned, it is certainly a most useful shop window for British aerospace products, and if few new orders are actually received at Farnborough, a very large number are announced— as our ’Orders and Contracts' column on page 332 bears witness. It is not possible to cover every exhibit displayed at the Farnborough Show but the following report describes a wide cross‐section beginning with the exhibits of the major airframe and engine companies.

An aeroplane comprises a body of delta planform, two wings extending from the ends of the base of the body and pivotally connected thereto for adjustment in sweep during flight, and means for rotating the wings during flight in relation to the body about an axis parallel to the OY axis of the aircraft irrespective of their position in sweep. In the illustration the body A comprises a central structure B, and two conical frame members CA, CB, are mounted in structure B by flanges D co‐operating with a fixed bearer (not shown), so that they can be rotated about axes parallel to the aircraft OY axis by independent fluid pressure jacks JA, JB. Each member CA, CB, has a pivot G on which a wing HA, HB is mounted so as to be variable in sweep. The wings HA, HB can thus be varied in incidence to suit the air speed and can be adjusted in incidence together for control, or differentially for roll control. A vertical stack of jet propulsion engines is located in a fin BA, with an air inlet L.

In combination with a by‐pass gas turbine engine comprising a low‐pressure compressor stage, a high‐pressure stage connected with the outlet of said low‐pressure compressor stage, combustion equipment connected with the outlet from the high‐pressure compressor stage, turbine means adapted to drive the compressor stages and connected to receive combustion gases from the combustion equipment, fuel supply means adapted to deliver fuel to said combustion equipment and including a fuel delivery conduit through which said fuel is delivered, a propelling nozzle, and a by‐pass duct connected at its inlet end to the outlet of said low‐pressure compressor stage and adapted to deliver the by‐passed air to the propelling nozzle to pass therethrough to atmosphere as a propulsive jet; a control arrangement comprising pressure‐responsive means connected to said by‐pass duct and adapted to respond to a rapid fall in pressure in said by‐pass duct, and valve means in said fuel delivery conduit and connected to said pressure‐responsive means to be operated thereby to reduce the fuel flow to the engine on sensing of a rapid fall in pressure in the by‐pass duct.

In a gas turbine plant adapted to operate according to a cycle at variable pressure but constant volume, a source of air under pulsating pressure comprising a centrifugal compressor having a centrifugal wheel with novable blades and a difTuser with stationary blades arranged downstream with respect to said wheel and adapted to transform into pressure the kinetic energy of the whole air output issuing from said movable blades, a pulsating source of hot gases including at least one combustion chamber fed with air under pulsating pressure from said difTuser for supporting combustion in said chamber, said chamber having an elongated form with dimensions adapted to give the chamber a resonance frequency tuned to the frequency of said pulsating pressure, fuel injecting means delivering fuel into said chamber, and control means for operating periodically said fuel injecting means at the frequency of said pulsating pressure, a gas turbine of the variable‐pressure operated type the intake of which has stationary expansion nozzles freely opened and connected to the said hot‐gas source, and coupling means between said gas turbine and said centrifugal compressor adapted to drive it.

Accles & Pollock Ltd. of Oldbury, Worcestershire, a TI Steel Tube Division company, will be exhibiting a comprehensive range of precision steel tube and tubular products, including plain, annularly convoluted and thin wall tube, at Farnborough.