Applied Mechanics and Materials Vols. 799-800

Abstract: Flow maldistribution and specifically in distributors has been a major area of study in engineering fluid dynamics. The literature shows some of the work done on the flow distribution in parallel tubes, nozzles, and air conditioning distributors and its effect on the pressure drop as well as the energy losses in the heat exchanger. This study aims at investigating the maldistribution of the flow in various geometries of the distributor, and trying to identify the geometry that causes the least maldistribution. FLUENT 14 software was used to carry out the CFD study in a one-phase flow (liquid), as well as in two-phase flow simulations. The results obtained show that the distributor geometry type 9, has the highest maldistribution, while type 8 has the least. The effects of the dispersion cone, the orifice, as well as erroneous tilting in installation/manufacturing, on maldistribution are also investigated. The orifice might actually lead to more maldistribution. And the cone was shown to have negligible effect on maldistribution.

Abstract: A novel evaporative cooling system, which uses an ejector for refrigeration, integrated with a membrane dehumidification module has been studied. In the system investigated, where ultrasonic nebulizers are utilized to pulverize water into droplets for evaporation. The cooling effect influenced by the intensity of ultrasonic automization has been experimentally studied. The prototype of the membrane module is made and several experiments are conducted to evaluate its effect on the system. It is found that, in a permanent inlet air condition, the temperature drop would increase as intensity of ultrasonic grows. Cooling effect of the ejector is better in dry ambient condition compared to moist one. When in the humid environment, the membrane module would increase the system refrigeration capacity by 80%.

Abstract: Space solar power satellite (SSPS) as a very large flexible spacecraft structure with complex configuration, large size and number of units bring the difficulties to dynamics modeling and analysis. Considering SSPS structure characteristics, equivalent strain and kinetic energy theory is adopted to establish the equivalent beam model of SSPS truss structure. The assumed mode method is adopted to describe the flexible body. The modal truncation method implements the dynamics system order reduction. Mixed coordinates method is adopted to establish the rigid-flexible coupled dynamic model. The established dynamic model can reflect dynamic characteristics of SSPS, achieve control requirements for SSPS and decrease the workload of simulation calculation. The independent modal space control (IMSC) method is proposed to active control research view of the large displacement, nonlinearity, low and dense mode frequency, light damping of flexible structures. Simulation results on flexible solar array show the effectiveness of the control method.

Abstract: when detonation wave is spreading in cylindrical charge which has a shell constraint, the border of the shell will reflect the detonation wave, reflection wave still has a strong influence on charge’s centerline. Compared with cylindrical charge, the influence of variable-section charge’s stack reflection wave on centerline is unsteady, relating to the gradual trends height of section area. On the condition of end-point detonation, doing the numerical simulation on detonation process of equal-section charge 、reduced-increased charge and increased-reduced charge, analyzing the pressure and velocity of detonation products on position of centerline, founding in the range of gradually decreasing section al, detonation wave through reflecting and then occur oblique collision that induce the pressure increasing rapidly. Doing the numerical simulation on variable-section charge’s detonation, promoting the understand of the reflection wave mechanism and the velocity of detonation product, this can be a practical significance to further improve the charge structure design and realize the efficient utilization of detonation energy.

Abstract: The waste heat emissions of thermal discharge from floating nuclear power plants may have a negative thermal effect on the environment. Study on the dilution and diffusion of cooling water plays an important role in thermal pollution prevention. The cooling water discharge process can be condensed into the thermal jet in cross flow. According to the theory of computational fluid dynamics, the mathematical model of round horizontal thermal jets in cross flow is established. The 3D numerical simulation of thermal jets based on finite volume method is achieved by using the Realizable k-ε turbulence model and the Semi-implicit method for pressure linked equations, and the three-dimensional trajectory of thermal jet are obtained. The rationality of analysis method is approved by comparing calculation value with experimental value. The temperature distributions in thermal jets are studied through the numerical experiments conducted under different cross-flow velocity and different emission angle. As a result, the impacts of these conditions on thermal pollution area are found, and the theoretic bases are provided for the design of the cooling water discharge pipe.

Abstract: In this paper, the structure of cylindrical shell with a reinforced circular cutout using combination model of solid element and shell element was analyzed by Finite Element Method (FEM) simulations. Multipoint constraint (MPC) method is mainly used to solve the connection between solid element and shell element when considering the calculation accuracy and efficiency of the model. The combination model of solid and shell element is established in ANSYS, and has been compared to the model of shell element and the model of solid element. The result showed that in the aspects of the stress distribution of the pressure hull near the cutout, buckling behavior of the structure and its instability response, the combination model of solid and shell element was almost equal to the others, it is convincible as well as possessing merits of other models.

Abstract: A finite element model of tailiings dam was used to analyze the dynamic responses of the stress field, displacement and acceleration of the dam with the dynamic time-history response analysis method in this paper. The time-history curves of different responses were obtained. And an evaluation for dynamic stability of the tailings dam was also discussed. The analysis result shows that this case can provide a certain reference value for the dynamic calculation and the dynamic stability analysis of tailings dam under seismic load.

Abstract: The aim of this investigation is to study the characteristics of solidification of flow through an elliptical pipe and to avoid the solidification and blockage in the pipe. A three-dimensional model has been completed using the commercial fluid dynamics code, Fluent. Analyses under different conditions show that different factors affect the characteristics of solidification and heat transfer in the pipe. The lower Reynolds number is or the higher dimensionless wall temperature turns, the thicker the ice layer becomes, which will increase the risk of blockage. The thickness at the long axis direction will grow with the increase of ellipse aspect ratio while it turns out contrary at short axis direction.

Abstract: At first, the unidirectional stress fatigue strength has been made the brief description, and the calculation methods about the fatigue stress under two cases also has been introduced, two cases are the symmetrical and asymmetrical cyclic stress fatigue strength. The calculation of fatigue strength is based on the fact that calculating safety factor is equal to or greater than the allowable safety coefficient. Finally, some alloy steel parts are taken as an example to carry on the fatigue strength calculation.

Abstract: The internal-meshing rotary mechanism is widely used in the oil pumps and cyclonical pin wheels application. The working principle of the internal meshing rotary compressor is very different with the current institutions applications. while, the mechanical property method of the internal meshing rotary pump can’t be entirely and directly used in the rotary compressor because of the different working principles. In order to simplify the study of the internal-meshing rotary compressors, the forces acted on the inner and outer gears are computed. The gas force and torque related to the rotating angle are derived, and then compared with other rotary compressors. The result shows that the internal meshing rotary compressor’s mechanical parameters vary periodically and the period is 2π/Z₂and this type of compressor has perfect mechanical property compared with other compressors.