Advanced Materials Research Vol. 744

Abstract: High-speed couplings are the key parts of micro-turbomachinerys. They are assembled to shafts by interference fits, which can transfer large torque, are easy to produce and offer significant cost advantages. Considering of the influences of the torque, rotational speed and temperature variation, the interference fits between couplings and shafts have to be analyzed accurately in order to save the construction cost and reducing risk of invalidation accidents. In this paper, a model of the interference fit between a coupling and a shaft is developed to study the determine parameters of the interference value. Using the classic elastic plane stress theory, the exact solutions of the radial stresses, hoop stresses and radial displacements are obtained. Three determine parameters (the torque, angular velocity and temperature variation correction terms) are derived in order to calculate the interference value. Taking a high-speed microturbomachinery for example, the numerical results show that the interference value is dependent of the ratios of inner radius to outer radius of the coupling and shaft significantly. The torque, angular velocity and temperature variation correction terms are in the same order of magnitude. The present analytical solutions are expected to be useful in the structure design of the interference fit between a high-speed coupling and a shaft.

Abstract: In this paper, Least Square method is applied to model the clearance wear to achieve the accurate prediction with low cost. So, firstly, the characteristics of the clearance wear are analyzed, i.e. time-variant, asymmetric, and coupling. Secondly, the dynamic incremental model is deduced from Archards wear law to obtain the wear incremental at a time step. Based on the wear data of the experiment, Least Squares Method is adopted to model the extrapolation function for divided sectors of contact surface. Finally, both models are applied to predict the clearance joint wear in the crank slider mechanism, getting two wear trend curves with great similarity. However, the computing time is greatly reduced in the extrapolated model.

Abstract: According to the plunger pump movement principle, this paper analyzed the two kind of typical force situation of the connecting rod, and obtained the theoretical maximum value of the force. The finite element analysis method was applied to analyze the structure strength of the connecting rod. The finite element model of the connecting rod was established, and the load handling and boundary condition was analyzed. The maximum stress 405MPa occurs at the transition from the small end to the link body. The average stress of the link body is 136MPa. The maximum displacement is 0.17mm, belongs to the small deformation range. The last results of the node stress and displacement show that the connecting rod can work safely.

Abstract: For the thin film lubrication, boundary lubrication, and local dry friction lubrication state of hydrodynamic bearing, a lubrication model of distributed liquid film is established in this paper which is designed to service for calculating or predicting the full life cycle design performance of water-lubricated bearing. The limitations of the fluid-solid-thermal coupling model for describing the distributed liquid film are investigated. Two new methods to build the lubrication model of distributed liquid film are given. The first one takes fluid-solid-thermal model that can guide the design of bearings parameters as dominant factor, and combines with wear, corrosion, two-phase of gas-liquid and other additional factors. A comprehensive model integrating simulation and mechanism can be built. Through researching the regional properties or distributed parameter of water film and solid interface, the second way proposes a decomposition and synthesis modeling method of water film and rubber. A distributed parameters model of dynamic characteristics for water-lubricated bearing is built. The lubrication theory of distributed liquid film proposed in this paper is appropriate for the situation when the film thickness is less than 10μm or contact. When the film thickness is greater than 10μm, classical lubrication theory is applicable.

Abstract: There is a need for a computational tool for analyzing creep damage problems for the research community and high temperature industries, and dedicated in-house software still has its merits and advantages. This paper reports the development of such software including the development of finite element algorithms based on CDM for creep damage analysis, and the use of some standard subroutines in programming, and sample of validation.

Abstract: The preliminary validation of in-house finite element analysis software for creep damage mechanics is reported. The Finite Element Analysis Method and the programme strcuture for creep damage problem were reported elsewhere and the validation conducted so far include plane stress, plane strain, and axisymmetric cases. Furture work is also outlined.

Abstract: In this paper, the three-dimensional CFD method is used in numerical simulation of the highly intensified diesel engine intake process. The effect of different intake flow compound modes on the highly intensified diesel engine is studied (Including compounded port with helical and tangential intake port, compounded port with two helical intake ports and compounded port with two tangential intake ports). By contrasting the instantaneous flow field, flow characteristic and inlet ability of the three compound modes, the pattern of influence on the inlet flow characteristics by compound modes is analyzed. The results indicate that the combinations of the intake port greatly affect the swirl rate and the inlet ability. The interference of the two helical intake ports is serious, causing more inlet loss. The two helical intake ports have the weakest inlet ability among the three types of intake ports. However, two helical intake ports can cause higher swirl rate. Two tangential intake ports inlet ability is the most excellent, but its swirl rate is the lowest.

Abstract: In order to research the NOx emission characteristics of the medium speed diesel engine DN8340, a finite element model is built. Calculate the influence of changing the intake charge temperature and injection timing on NOx emission, and forecast how it works to decrease the intake charge temperature and delay injection timing by the methods of Miller-cycle, oscillating cooling piston and electronic controlled high pressure common rail. The calculation result shows that Decreasing the intake charge temperature and delaying the injection timing can reduce the NOx emission to 2.22g/kWh effectively which meets the requirement of IMO TierIII.

Abstract: Two models with and without insulating clapboard were established. The electric potential distribution and the flow of electric current in electrolytic cell under the two models were simulated by Ansoft finite element software. The results show that the distribution of equipotential surface is the most intensive in the area close to the electric plate,and the current in the cell obviously skewed flows to the bottom of the strip under the insulating clapboard model , which is important to improve the current efficiency of the electrolytic cleaning. Finally, the influence of insulating clapboard on current efficiency and under different plate spacing were carried on by experiment and analysis, proved the correctness of the simulation results.

Abstract: This paper presents a new heat-work device, which chooses the gear-rack mechanism to realize the reciprocating motion of cylinder, and that applies swing rod rotation to transmit thermal energy, it changes the use of traditional engine crank-link mechanism and improves the mechanical transmission efficiency effectively. Using incomplete gear mesh, the length of displacement can change in the exhaust stroke, so that the combustion exhaust gas can discharge more. The premix gas is completed ahead of schedule two stroke earlier than traditional gasoline engine in the auxiliary cylinder, and mixture gas burn more thoroughly. To combine swing rod with overrunning clutch install on the output straight shaft, it can replace the crankshaft for output power.