Applied Mechanics and Materials Vols. 716-717

Abstract: Vacuum dampening is a crucial step in the tobacco production. It needs to vacuumize the tank to a specified value, and then injects water mist to dampen the tobacco packages. This paper analyzes the control principle and technical indexes of a Vacuum Dampening Machine, and the influence dampening effects of the two systems (vacuum system and dampening system). It found that the vacuum system of Level 3 Section 4 and bottom dampening are predominant.

Abstract: Based on the analysis of the structures of Drum Loose Dampening Feeder, we found some problems and carried on researches, put forward some improvements in accordance with the actual applications, and achieved significant effects.

Abstract: For the horizontal well of petroleum drilling engineering, the horizontal section of drill string was selected as a research object. Collision and friction between drill string and well wall, displacement response on the drill bit and other boundary conditions were considered in this simulated modeling. By using finite element analysis software ANSYS, the dynamic characteristics of horizontal section of drill string were calculated and discussed. The effect of different positions of stabilizers on the vibration characteristics of drill string were studied specially. The calculated results show that the installation positions of stabilizers have remarkable effects on the dynamic characteristics of drill string. It will change the lateral vibration and whirling motion of drill string remarkably. Furthermore, the reasonably installation of the stabilizers can decrease the amplitudes of lateral vibration and transient torque. Those results may provide some guidance for the vibration analysis of drill string system.

Abstract: Aimed at braking large mass impact loading problem, a mathematical model of the multi-orifice hydraulic buffer has been established, with the use of hydrodynamics theory, hydraulic theory and engineering structural mechanics theory. Damping characteristic curves under different operating conditions have been analyzed. The problem that traditional hydraulic buffer damping characteristics could not match to different mass impact loading well has been found. By analyzing the influence of buffer cylinder structural parameters on buffer damping characteristics, a variable damping buffer has been proposed, and the problem has been verified with simulation.

Abstract: Aimed at braking large-mass unidirectional impact loading problem, the impact loading characteristics has been analyzed and a mechanical model has been established. A new improved Bingham model has been proposed to solve the problem of big error in traditional Bingham model in low-velocity region. Unlike the traditional Bingham model, there are two different kinds of expression of damping force on both low-velocity and high-velocity region in the improved Bingham model. Thus, the accuracy of the model has some improvement, and it has been verified with simulation.

Abstract: Researches on vibration of centrifugal pump induced by fluid exciting forces are significant for reducing equipment faults, which are caused by the vibration transferring from the base, and noise emission of shells which connected with the base. Fluid exciting forces are the main vibration sources in centrifugal pump systems. The vibration of impellers is generated by fluid exciting forces, and transferred to mechanical systems through pump shell and shaft bearings. By optimizing of inner flow filed of centrifugal pump, not only the fluid exciting forces can be reduced, but also the vibration level of the pump can be improved. In this paper, based on reducing noise and isolating vibration, the inner flow field of the centrifugal pump was emulated by CFD method. The flow field was optimized by controlling the impellers cutting process. The optimizing results were shown by comparing the pressure pulsation of the optimized flow field with those of the original flow field. The improvement of optimization was verification by measuring the vibration responses of the centrifugal pump base structure. The experimental results shows that: the level of flow field excitation and the pressure pulsation of flow field under the blade frequencies and multiplication frequencies are declined to some degree by cutting impellers; the vibration responses of pump base decreased 4.5 dB after cutting impeller.

Abstract: An approach of combining the rigid body theory and improved Fourier series method is proposed to model the single-stage isolation system based on an elastic plate-shell coupled structure, and the isolation performance is investigated. Considering the practical problems of the machinery system design in the field of marine engineering, the influences of various structural parameters on the isolation performance for the isolation system is implemented. The numerical simulation results are given and discussed.

Abstract: To realized the parametric design of automobile synchronizer ring spline tooth efficiently, a method is presented in this article, which is realized based on the UG secondary development tools. The user environment settings and the establishment of the menu file and the human-computer interaction window are introduced in detail. The programming language is written to realize the parametric design of the spline tooth of synchronous ring. Application result shows that the method simplifies the synchronous ring modeling process and improves the working efficiency.

Abstract: The multi-stage centrifugal pump run instability at the original design point, and the running operating point deviated far from the design point during the run. In order to better meet the multi-stage centrifugal pump operational requirements, through hydraulic model modification, changing the multi-stage pump design point, while the performance curve before and after the modification can be interchangeable in the flow of 150m3/h~320m3/h. The original program used 3 blades impeller. Taking into account the matching problem with pressurized water chamber, modification plan used 5 blades impeller. Analysis on the internal flow field before and after the modification was made. Through comparison the internal and external characteristics of the two plans, the analysis found that in the double volute pressurized water chamber, the flow field symmetry of 5 blades is better than the 3 blades’. The flow field symmetry can be well balanced radial force, and help to improve the instability phenomenon in operation.

Abstract: A 3-D model of pelton turbine bucket was built to investigate the motion characteristics of sediment particles in pelton turbines and the erosion caused by the movement. With the assistance of fluid analysis software FLUENT, A continuous phase turbulence model was estimated by the Euler equation which achieved convergence and the selected coupled calculation for solid-liquid two-phase flow with DPM model was built. It can be draw from the numerical analysis that, with the same size and sediment concentration, the inner bucket wall would suffer from the greater erosion by the relatively greater flow velocity; under the same condition of flow velocity and sediment concentration, the more serious erosion was caused by the bigger sized sediments; and the greater sediment concentration led to greater erosion, given the same flow velocity and sediment size. Based on the study, it showed that the erosion of inner wall of buckets was mainly affected by sediment size and concentration, as well as flow velocity.