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In hydraulically‐operated retractable wheels for aircraft the actuating member comprises a jack having a piston connected on one side with a motive pump and an exhaust, and on the other side with a hydro‐pneumatic pressure accumulator into which the liquid is forced by the jack during each lifting operation, the stored energy in the accumulator actuating the jack to assist the action of gravity when lowering the wheels. The retractable wheels R (Fig. 1) are each pivoted at A and connected to a fluid‐operated piston in a cylinder V pivoted at T, the wheels being drawn up into the machine through spring‐operated doors C1, D1 which are opened by fluid‐operated means G2 (Fig. 2) when the wheels are lowered. The cylinder V is connected by pipe 3 and non‐return valve 4 to a pump 1 supplied from a reservoir 2, surplus liquid being bye‐passed from the pump through a pipe 16. A pipe 5 for exhausting the cylinder V is connected through a manually‐operated valve 6 to the reservoir 5 and a branch 3a from the pipe 3 is connected to a cylinder 8 whereby pressure is applied to move valve 12 and non‐return valve 10 to place the other end of the cylinder V to discharge through pipes 3b, 3e to a pneumatic accumulator 9 supplied with air from a cylinder 14. When pressure is supplied by the pump 1 to the cylinder V to retract the wheels, a projection on the valve 12 opens the valve 10 and the liquid in the other end of the cylinder is forced into the accumulator 9, and when the wheels are to be lowered the valve 6 is opened by the lever 7 to exhaust one end of the cylinder into the reservoir 2 while the other end of the cylinder is supplied with pressure fluid from the accumulator. A pipe 17 from the pump 1 is connected to a cylinder G2 and is provided with a branch 18 and manually‐operated valve 19 whereby the cylinder may be exhausted. The cylinders G2 (Fig. 5) are connected by links to the doors C1, C2 maintained in the closed position by springs r1, r2, the doors C1, C2 being interconnected to open smaller doors D1 (Fig. 1) which remain open when the wheels R are lowered. The levers 25, 20, 7 (Fig. 2) are connected to a single control lever. In Fig. 10, the wheel arm J is pivoted at A and is connected by piston rod P to the cylinder V pivoted at T. A wire 35 connected to the arm J passes over pulleys 36, 37, and is connected to a piston in a horizontal cylinder 41 open to a pneumatic reservoir 9. When the wheel R is raised to the position R1 by the admission of fluid under the piston P, the wire 35 rapidly withdraws the piston in the cylinder 41 to compress the air in the accumulator 9, and since the effect of gravity is not so pronounced between the positions R, R1 as between R1, R2 and the fact that the air pressure on R tends to raise the wheel, the pressure applied to the piston P is mainly stored in the accumulator 9. From the position R to R1 the effect of air pressure is less and gravity greater, so that between these positions the wire 35 is adapted to lap around a pulley 43 on the axis A whereby the movement of the piston in the cylinder 41 is small and less power is stored in the accumulator 9, the pressure on the piston P being primarily expended in raising the wheel from R1 to R2. Similarly when lowering the wheel the accumulator expends the greatest power between R1, R. A device for recovering any leakage from the pump 1 when the reservoir 2 is at a higher level is shown in Fig. 9. A leakage pipe 28 is connected by a housing 29 and pipe 30 to the suction pipe 33, and the housing contains a float 31 with upper and lower needle valves. When the housing 29 is full of liquid, the pipe 28 is closed by the upper needle valve and the liquid in the housing is withdrawn through pipe 30 and when the housing is empty the float falls and closes the pipe 30.

The purpose of this paper is to propose a partitioned approach by coupling the smoothed profile method (SPM) and the Euler tension beam model in simulating a vortex-induced vibration of both rigid and flexible cylinders at various reduced velocities.

For the fluid part, SPM in the framework of the spectral element method is adopted to simulate the flow. The advantage of SPM lies in modelling multiple complex shapes as it uses a fixed computational mesh without conformation to the geometry of the particles. For the structure part, an elastic-mounted rigid cylinder is considered in two-dimensional (2D) simulations, while a flexible cylinder with a Euler tension beam model is used in three-dimensional simulations.

Firstly, in the flow past a freely vibrating cylinder, the maximum vibration responses of the cylinder are about 0.73D and 0.1D in the y and x directions, respectively, which occur at the point U_r = 5.75 and are much higher than U_r = 5 in 2D simulations. It is found that the numerical results from the SPM solver are very consistent with those from the NEKTAR-Arbitrary Lagrangian Eulerian method (NEKTAR-ALE) solver or the NEKTAR-Fourier solver. Furthermore, the flow past the tandem cylinders is also investigated, where the upstream cylinder is static while the downstream one is free to vibrate. Specifically, the beating behaviour is captured from the vibration response of the freely vibrating cylinder under the reduced velocity of U_r = 6 with a gap distance of L = 3.5D.

The originality of the paper lies in coupling the SEM with the Euler beam model in simulating the vortex induced vibration (VIV) of flexible cylinders.

In this paper, wear of the cylinder is taken to mean not only wear of the liner but of the piston ring assembly also, since usually, though not always, the wear of the one is closely related to that of the other. The wear process may be corrosive, abrasive or frictional, and it is likely that all three processes occur together to varying extents, depending on such factors as engine design and operating conditions.

The purpose of this paper is to provide the guidance on a design and integrity evaluation of a cylinder under pressure, for which stress analysis has been done for transversely isotropic thick-walled circular cylinder under internal and external pressure with thermal effects.

Transition theory has been used to evaluate plastic stresses based on the concept of generalized principal Lebesgue strain measure which simplifies the constitutive equations and helps to achieve better agreement between the theoretical and experimental results.

It can be concluded that circular cylinder with thermal effects under internal and external pressure made of isotropic material (steel) is on the safer side of the design as compared to the cylinder made of transversely isotropic material (i.e. magnesium and beryl) because percentage increase in effective pressure required for initial yielding to become fully plastic is high for isotropic material (steel) as compared to transversely isotropic material (i.e. magnesium and beryl). It can also be concluded that out of two transversely isotropic materials, beryl is better choice for design of cylinder as compared to magnesium material because percentage increase in effective pressure required for initial yielding to become fully plastic is high for beryl as compared to magnesium.

A detailed investigation of thermal transversely isotropic thick-walled circular cylinder under internal and external pressure has been done which leads to the idea of “stress saving” that minimizes the possibility of fracture of cylinder.

Frictions in cylinder liner-piston ring often cause an inevitable loss of energy loss in the diesel engine. This study aims at evaluating the effect of depths in the cylinder liner groove texture on friction, wear and sealing performances.

Five depths of groove texture cylinder liners (50, 100, 150, 200, 250 µm) were fabricated, and experiments were carried out using a special-purpose diesel engine tester. Comparative analyses of cylinder liner contact resistances, piston ring wear losses and surface appearances were conducted with respect to different surface textures and applied loads.

Under no-load conditions, the cylinder liner with a 100 deep thread groove can significantly improve sealing and optimize its lubrication performance. On the other hand, the sealing is highly correlated with the depth of groove and the load within the cylinder liner. Under loaded conditions, the thread groove has less effect on the sealing performance.

The findings can provide feasible basis for the tribological design and production of diesel engines.

The purpose of this paper is to investigate creep in an internally pressurized thick-walled, closed ends cylinder made of functionally graded composite, having linear and non-linear distribution of reinforcement, using finite element (FE) analysis.

FE-based Abaqus software is used to investigate creep behavior of a functionally graded cylinder. The cylinder is made of composite containing linear and non-linearly varying distributions of reinforcement along the radius. The creep behavior has been described by Norton's power law. The creep stresses and strains have been estimated in linear and non-linear functionally graded materials (FGM) cylinders and compared with those estimated for a similar composite cylinder but having uniform distribution of reinforcement.

The radial stress in the composite cylinder is observed to decreases over the entire radius upon imposing linear or non-linear reinforcement gradients. However, the tangential stress in the cylinder increases near the inner radius but decreases toward the outer radius, on imposing linear or non-linear reinforcement gradients. The creep strains in the FGM cylinders are significantly lower than those observed in a uniform composite cylinder.

The creep strains in an internally pressurized functionally graded thick composite cylinder could be reduced significantly by employing non-linear distribution of reinforcement along the radial direction.

A SPANWISE rotating cylinder placed at a suitable location in an aerofoil with the cylinder's upper surface moving rearwards in the direction of the local air flow can serve to re‐energize the boundary layer on the aerofoil. For example, when placed between a flap and a wing with the cylinder protruding substantially into the air flow as shown schematically in no. 1, the moving surface of the cylinder destroys, by viscous shear action, the low‐energy boundary layer impinging on the cylinder from the wing and results in a new boundary layer on the flap's upper surface which has a higher energy level adequate to negotiate the adverse pressure gradients and flow conditions existing at the rear of a flap deflected through a large angle. The boundary layer re‐energizing function of the cylinder depends on its upward protrusion, on its peripheral speed, and on the local flap geometry. The beneficial effects of the rotating cylinder on the flow fields have been visualized in two dimensional smoke studies conducted by Alvarez Caldcrón and Arnold of Stanford University on a flap designed for deflected slipstream V/S.T.O.L. aircraft. Fig. 2 shows flow around the flap with the cylinder stationary. It exhibits complete flow separation at the flap which is also typical of a slotted flap deflected through a large angle. The large white disk is a cylinder end plate; the actual cylinder appears in the darker circular shade of small diameter. The photograph of FIG. 3 was taken with the cylinder rotating: it shows a radical flow change not only in the total elimination of flow separation on the flap but in the induction of strong upwash fields and low pressure regions toward the leading edge of wing itself which obviously greatly increases lift and decreases wing pitching moments.

The purpose of this study is to prolong the service life of the Al–Si alloy cylinder and achieve the objective of energy saving and emission reduction by the composite treatments.

Chemical etching + laser texturing + filled MoS₂ composite treatment was applied to the friction surface of aluminum–silicon (Al–Si) alloy cylinder. The friction coefficient and wear loss were measured to characterize the tribology property of cylinders.

The composite-treated Al–Si alloy cylinder had the lowest friction coefficient and weight loss. The friction coefficient and weight loss of the composite treatment were approximately 27.08% and 54.17% lower than those of the untreated sample, respectively. The laser micro-textures control the release of solid lubricant to the interface of friction pairs slowly, which prolongs the service life of cylinders.

The synergistic effect of the chemical etching + laser texturing + filled MoS2 modified the tribology properties of Al–Si alloy cylinder. The chemical etching raised the silicon particles to bear the load, and laser micro-textures control the release of solid lubricant to improve the lubrication property.

This paper aims to investigate magnetic impacts on bioconvection flow within a porous annulus between an outer cylinder and five inner cylinders. The annulus is filled by oxytactic microorganisms and nano-encapsulated phase change materials.

The modified ISPH method based on the time-fractional derivative is applied to solve the regulating equations in Lagrangian dimensionless forms. The pertinent factors are bioconvection Rayleigh number Ra_b (1–100), circular cylinder’s radius R_c (0.1–0.3), fractional time derivative α (0.95–1), Darcy parameter Da (10⁻⁵–10⁻²), nanoparticle parameter ϕ (0–0.1), Hartmann number Ha (0–50), Lewis number Le (1–20), Peclet number Pe (0.1–0.75), s (0.1–0.9), number of cylinders N_Cylinders (1–4), Rayleigh number Ra (10³–10⁶) and fusion temperature θ_f (0.005–0.9).

The simulations revealed that there is a strong enhancement in the velocity field according to an increase in Ra_b. The intensity and location of the phase zone change in response to changes in θ_f. The time-fractional derivative a acting on a nanofluid velocity and flow characteristics in an annulus. The number of embedded cylinders N_Cylinders is playing a significant role in the cooling processes and as N_Cylinders increases from 1 to 4, the velocity field’s maximum reduces by almost 33.3%.

The novelty of this study is examining the impacts of the magnetic field and the presence of several numbers of embedded cylinders on bioconvection flow within a porous annulus between an outer cylinder and five inner cylinders.

This study aims to numerically explore the heat transfer characteristics in turbulent two-degree-of-freedom vortex-induced vibrations (VIVs) of three elastically mounted circular cylinders.

The cylinders are at the vertices of an isosceles triangle with a base and height that are the same. The finite volume technique is used to calculate the Reynolds-averaged governing equations, whereas the structural dynamics equations are solved using the explicit integration method. Simulations are performed for three different configurations, constant mass ratio and natural frequency, as well as distinct reduced velocity values.

As a numerical challenge, the super upper branch observed in the experiment is well-captured by the current numerical simulations. According to the computation findings, the vortex-shedding around the cylinders increases flow mixing and turbulence, hence enhancing heat transfer. At most reduced velocities, the Nusselt number of downstream cylinders is greater than that of upstream cylinders due to the impact of wake-induced vibration, and the maximum heat transfer improvement of these cylinders is 21% (at U_r = 16), 23% (at U_r = 5) and 20% (at U_r = 15) in the first, second and third configurations, respectively.

The main novelty of this study is inspecting the thermal behavior and turbulent flow–induced vibration of three circular cylinders in the triangular arrangement.