Applied Mechanics and Materials Vols. 635-637

Abstract: Control problems are considered for a two-dimensional model describing wave scattering in an unbounded homogenous medium containing an impenetrable covered (cloaked) boundary. The control is a surface impedance which enters the boundary condition as a coefficient. The solvability of the original scattering problem for 2-D Helmholtz equation and of the control problem is proved. Optimality system dгescribing the necessary extremum conditions are derived. The algorithm for numerical solving of the control problem based on the optimality system and boundary element method is designed.

Abstract: Taking the air intake pipe in the engine as the target of the research, the software STAR-CDE is adopted to build a three-dimensional simulation model for the air intake pipe in the engine T12V190 with the aim to solve the problems of air input deficiency, Combustion deterioration and performance reduction of one cylinder caused by the non-uniformity. Moreover, the non-uniformity of the flux of air intake of the air intake pipe is mainly studied and analyzed through a calculation on the CFD of the inner flow field of the three dimension of the air intake pipe in the engine T12V190. In addition, a retrofit design with multiple schemes is made based on the cavity structure of the original mold for the air intake pipe. Finally, through a comparison among the three selected designs, a more feasible retrofit designing scheme and a designing thought on the air intake pipe in the engine with directional significance are got.

Abstract: We consider control problems for 2-D Helmholtz equation in a bounded domain with partially coated boundary. These problems are associated with acoustic cloaking. Dirichlet boundary condition is given on one part of the boundary and the impedance boundary condition is given on another part of the boundary. The role of control in control problem under study is played by surface impedance. Solvability of control problem is proved and optimality system is derived.

Abstract: Countercurrent cyclones have been quite widely applied in various industries [1-12]. In this paper, on the example of classical construction of countercurrent cyclone considers the impact of the conical nozzle on the exhaust pipe to the gas-dynamic picture and efficiency dedusting.

Abstract: To ensure fresh water cooling system in a certain self-elevating drilling unit to work securely, the pipes of fresh water cooling system, which are immerged in ballast water tanks, are analyzed and designed by means of convective heat exchange and heat conduction. The calculated results show that it’s unnecessary to adopt insulating measures for the pipes of the fresh water cooling system exposed in sea water, and it saves cost for shipyard and ship owner. The references are afforded to the design of fresh water cooling system in the process of self-elevating drilling unit shipbuilding in the future.

Abstract: The FLUENT6.3 software is applied to simulate the supersonic flow in micro convergent-divergent nozzle. The simulation is complemented by computing steady 2-D Navier-stokes equations to analyze the pressure contour and velocity contour inside the micro nozzle which has straight exit section or not and the length of straight exit section l. Also the performances of fluent mass coefficients and thrust force efficiencies are studied. The numerical results show: That the nozzle has straight exit section or not and the section length l affect the pressure contour and velocity contour inside the thruster. Compared to the nozzle that has no straight exit section, the minimum pressure region and the maximum velocity region are close to the center of exit in the nozzle that has straight exit section. Also the affected region is increased. When the throat Reynolds number Re is small, the flow coefficient C_d and thrust coefficient η_F firstly increase then decrease with the increase of l.

Abstract: Aiming at high voltage electrostatic field of melting electron beam gun system, taking 30 kv 60 kw melting electron beam gun for example, the structure of the electric field and boundary conditions was designed. And the mathematical model of the electric field was established. The method of numerical calculation was used to solve the mathematical model, and Matlab software was used to simulate the equipotential lines of the electric field. The electrolytic cell experiment was used to simulate high voltage electrostatic field distribution of the electron beam system. At the same time compared with the two different results, the reasons and the improved method were analyzed. For research and calculation high voltage electrostatic field of processing equipment such as electron beam welding, melting, etc, offers a more general analysis, design and calculation methods.

Abstract: Grid division is the geometric expression forms and vectors of CFD numerical simulation engineering problems. The quality of the grid has an important impact on the CFD accuracy and computational efficiency about CFD. In this paper, it compares the structured and non-structured grid process summary base on blade pump. During a large number of mechanical fluid grid division and performance calculations, and combining with the theoretical guidance based on rotating machinery fluid Dynamics calculations, it summarizes some experience and practice on blades grid division optimization.

Abstract: The pulverized coal combustion in precalciner in the cement plant with capacity of 5000t/d was investigated by numerical calculation using Fluent software. The standard k-ε model and particle stochastic trajectory model was proposed to simulate the three-dimension turbulence flow and pulverized coal movement respectively. The energy equation including P1 raditional model and non-premixed combustion model were applied to calculate the internal flow field of temperature and concentrations of volatile, CO, O₂ and CO₂. It indicates that the structure of precalciner is well designed and the pulverized coal can burn quickly after injecting from burners. The decomposition temperature that production needed is satisfied and the concentrations after combustion are accepted.