Study on Vibration and Bifurcation of an Aeroengine Rotor System with Elastic Ring Squeeze Film Damper

To analyze the problem of vibration and bifurcation in the rotor system of the aeroengine with the elastic ring squeeze film damper (ERSFD) and elastic supports, the theoretical equation of the dynamic rotor system is developed in this paper, based on the rotor system, elastic ring squeeze film damper (ERSFD), and three elastic supports. The estimated analytical solution of the oil film force is solved using the short bearing approximation theory and the semi-oil film inference theory in the suspension and the inner and outer boss contact. Considering the oil film stiffness and damping of rolling bearings, the rolling bearing force model is established based on the elastohydrodynamic lubrication (EHL) theory. By the average method, the vibration and bifurcation modes are obtained concerning the bearing coefficient and parameters. The range optimization of parameters can be appropriately improved to enhance the dynamic characteristics of the device given different parameters of the hole of oil seepage, the stiffness, the position of elastic supports, and other structural parameters.

Experimental and numerical investigations on novel models for mechanical behaviors of the elastic ring in aero-engine

The elastic ring is widely used in elastic support structures of aero-engine because of its simple structure and convenient manufacturing. In this paper, two elastic ring models, 3D and 2D models, are proposed, where the fillets between the bulges and ring are considered. The 2D model is more efficient for the calculation of stiffness characteristics. The 3D model can be used to obtain the maximum stress position in the axial direction. Then the experimental testing is carried out to verify the accuracy and effectiveness of the proposed models. Based on the proposed models, the stiffness nonlinearity and critical load of the elastic ring are found for the first time, which can be used to determine the normal working load range. Moreover, the elastic ring models with and without fillets are developed, and the effect of the fillets on stress is discussed. The results show that the stress is reduced by considering the fillets, which are not considered in the existing literature.

Elastic multi-blisters induced by geometric constraints

We study a prototypical system describing instability effects due to geometric constraints in the framework of nonlinear elasticity. By considering the equilibrium configurations of an elastic ring constrained inside a rigid circle with smaller radius, we analytically determine different possible shapes, reproducing well-known physical phenomena. As we show, both single- (with different complexity) and multi-blister configurations can be observed, but the lowest energy always corresponds to single-blister solutions. Important physical insight is attained through an analogy between the elastica and the dynamics of a nonlinear pendulum. A complete geometric characterization is attained, proving symmetry and other relevant properties. The effectiveness of the model is tested against a simple experiment by considering a thin polymer strip constrained in a rigid cylinder.

In-Plane Vibration of a Deployable Segmented Ring

The in-plane vibrations of regular polygonal rings composed of rigid segments joined by torsional springs are studied for the first time. The nonlinear dynamical difference equations are formulated and solved by perturbation about the equilibrium state. As the number of segments increase, the frequencies, if aptly normalized, converge to the classical vibration frequencies of a continuous elastic ring. The vibration mode shapes are illustrated. The tiling of many identical polygons is discussed. Possible applications include the vibrations of space structures and graphene sheets.

DIESEL INJECTOR PUMP WITH RING CONTROL VALVE

The studies were carried out with the aim of modernizing the pump injector with a hydraulic actuator of the HEUI system plunger with the development of a control valve model based on a split elastic ring that provides fast fuel injection control. The upgraded device differs from the existing ones in that instead of a control freely floating valve (ball) or a poppet valve with springs, a valve in the form of a split elastic ring is installed in the valve assembly. One end of this ring is fixed rigidly, the other is freely movable to block the drain channel of the liquid. The canal overlaps the free edge of the ring when the electromagnet is turned on (installed with a gap inside the ring), and also (in the absence or malfunction of the electromagnet) from the valve itself running under the pressure of the supplied fluid. When upgrading the pump injector by the proposed method and using an annular control valve with electronic control (with optimal ring parameters), a new technical effect is achieved - reducing the response time of the control valve. This is due to the fact that the free edge of the split elastic ring, like a mechanical multiplier, blocks the drain canal π times faster than the valve stroke when it rises from the pressure of the fluid flow or signal when the electromagnet is on. The ring valve simultaneously acts as a spring to return to its original position, simplifying the design as much as possible. In the course of research, a new mathematical expression was derived for calculating the valve stroke depending on its design parameters. Using this formula, the optimal parameters of the control ring valve of the pump injector were established, which affect the quality of fuel injection in a wide range of diesel operation: diameter - 20 mm, ring width - 12 mm, thickness - 0.46 mm, diameter of the control fluid supply canal - 3 mm.

DIESEL INJECTOR PUMP WITH RING CONTROL VALVE

The studies were carried out with the aim of modernizing the pump injector with a hydraulic actuator of the HEUI system plunger with the development of a control valve model based on a split elastic ring that provides fast fuel injection control. The upgraded device differs from the existing ones in that instead of a control freely floating valve (ball) or a poppet valve with springs, a valve in the form of a split elastic ring is installed in the valve assembly. One end of this ring is fixed rigidly, the other is freely movable to block the drain channel of the liquid. The canal overlaps the free edge of the ring when the electromagnet is turned on (installed with a gap inside the ring), and also (in the absence or malfunction of the electromagnet) from the valve itself running under the pressure of the supplied fluid. When upgrading the pump injector by the proposed method and using an annular control valve with electronic control (with optimal ring parameters), a new technical effect is achieved - reducing the response time of the control valve. This is due to the fact that the free edge of the split elastic ring, like a mechanical multiplier, blocks the drain canal π times faster than the valve stroke when it rises from the pressure of the fluid flow or signal when the electromagnet is on. The ring valve simultaneously acts as a spring to return to its original position, simplifying the design as much as possible. In the course of research, a new mathematical expression was derived for calculating the valve stroke depending on its design parameters. Using this formula, the optimal parameters of the control ring valve of the pump injector were established, which affect the quality of fuel injection in a wide range of diesel operation: diameter - 20 mm, ring width - 12 mm, thickness - 0.46 mm, diameter of the control fluid supply canal - 3 mm.