Applied Mechanics and Materials Vols. 423-426

Abstract: Thermal water jet is an important part of the synthetically de-icing equipment designed to cut the frozen ice and snow on the public facilities. The inner structures of the jet nozzle, such as the conical and straight conical nozzles, have a crucial influence on the final efficiency of the cutting. In order to figure out the effect of these two kinds of nozzle structures to the jet fluid, and provide some strong references for the structure optimization, this paper synthetically uses ICEM CFD and ANSYS FLUENT software to analyze the fluid of the conical and straight conical jet nozzles. The results show that: as the initial conditions are determined, the conical nozzle has a higher speed and longer isokinetic core zone of the flux than that of the straight conical nozzle, and the speed changes more dramatically. However, the straight conical nozzle has a more stable speed, and lower operating vibrations. Through repeated indoor experiments, the simulation results are demonstrated.

Abstract: Numerical investigations are conducted to simulate the flow field of a 2D converging-diverging nozzle, for fluidic thrust vectoring. The numerical simulation of nozzle flow is carried out with Navier-Stokes equations model. Simulations are done with different primary and secondary jet conditions. The numerical results show that the smaller of the distance between secondary jet and exit, the larger is the thrust deflection angle. As the injection pressure ratio increases, the deflection angle increases followed on the premise of not far between secondary jet port and exit. The parameters play important roles on thrust vectoring capability.

Abstract: Static force measurement aerodynamic wind tunnel test data provided by the aircraft normally used to predict the stall characteristics, predicted aircraft deviated,spin Sensitivities, numerical simulation of aircraft stall, spin dynamics and so on. Based on practical flight, the paper analyzed the harm of limit state flight-spin to the flight safe, emphasized the static force test techniques at high angles of attack, and obtained a series of aerodynamic test date, managed them to spin prediction analysis.

Abstract: The genetic algorithm was employed to Multidisciplinary Design Optimization of transonic internally cooled turbine blades based on the conjugate heat transfer (CHT) method. Firstly, a parametric modeling method was employed to model the internal-cooled blade.Comparison of the SST turbulence model with and withoutγ-θtransition model was conducted, and the influence and reason between turbulent region and heat transfer distribution was analyzed.The result shows that separation appeared after middle region of the suction surface, because of the pressure after shock wave decrease abruptly that reduce adverse pressure gradient resistance capacity of laminar flow, it leads to instability and transition, and then enter a state of turbulence, same to the heat transfer coefficient with the phenomenon of abrupt increase that impact the temperature distribution, consequently SST model with γ-θ transition is better to showcase the change of aerodynamic and heat transfer in the transition region; Then,comparing the cooling effectiveness with different number cooling holes of internal-cooled blade , four cooling channels case was the best choice in consideration of the cooling effectiveness and the manufacturing process and the cost of the blade; In the end, Automatic optimization process was set up ,andseveral optimization frameworks were achieved. With the cooling flow increase in 0.011849 kg/s, average temperature and maximum temperature were reduced by 4.92% and 1.55% respectively in the boundary conditionsoptimization, in addition to optimized the cooling flow and the cooling effectiveness, temperature distribution in the part of contrastive analysis of turbulence model was verifiable, Simultaneously it is important guiding significance for the geometry parameters optimization.

Abstract: A two-dimensional finite volume method with unstructured mesh is used to simulate the flow around four square cylinders in a square configuration at low Reynolds numbers.The vorticity field, drag and lift coefficients, and Strouhal number are resolved at different spacing ratios. The vortex-shedding process and fluid-structure interactions of four square cylinders are analyzed at Reynold number of 100. The results show that the spacing ratio has important effect on the drag and lift coefficients. The accuracy of the numerical scheme are validated against other numerical and experimental data.

Abstract: With continuous developments of the manned space flight and planetary exploration missions, a new inflatable re-entry aeroshell becomes one of the hot topics of international research. It has the obvious advantages of the easy package, light weight, large resistance area, the low coefficient of ballistic, and the small heat generated by hypersonic air. This vehicle can provide a new way for the emergency return of astronauts, deep space instrumentation and payload recovery. This paper focuses on an inflatable membrane aeroshell with a single loop. Three kinds of cone angle of 75 degrees, 90 degrees and 105 degrees are respectively studied aerodynamic drag. These results show that aerodynamic drag is relationship not only with cone angle but also aerodynamic configuration.

Abstract: The boiling flow of LNG releasing underwater was numerically simulated by establishing liquid-liquid boiling flow transfer models and using multi-fluid model in FLUENT. The effects of quenching, average bubble diameter and turbulencemodel on the characteristics of hydrodynamic, heat and mass transfer processes were demonstrated. The results showed that in the progress of heat transfer between LNG and water, surface quenching makes an important role. The heat and mass transfer rate was influenced by valuing average bubblesdiameter. Because of per-phase turbulent flow making an equilibration important role in boiling flow process, turbulence models must be simulated respectively.

Abstract: There are two percolation models, horizontal radial flow above perforation interval, and semispherical centripetal flow below perforation interval. Based on this models and the theory of percolation flow through porous media, a study on prediction of water breakthrough time in fractured gas reservoir with bottom water is presented. Through mathematical calculations, a formula to determine the time of water breakthrough in fractured gas reservoir with bottom water wells is derived. Case study indicates that water breakthrough time decreases with the fracture development index. With increase of perforated degree, water breakthrough time increase first and then decreased after a critical value, which could be considered as optimum perforation degree. If the perforated degree is fixed, the water breakthrough time is directly proportional to the thickness of the gas reservoir and inversely proportional to the gas production rate.

Abstract: There are various shapes of capillary tubes in the rock, and the flow in triangles and rectangles capillary tubes has been studied very little. In this paper, the approximate solution of the distribution of the velocity in triangles capillary tubes has been obtained using variational method. The quantitative relation between pressure difference and flow rate in the two kinds of capillary tubes has been obtained by integrating in the entire capillary tubes, which is similar to Poiseuille's law. this study also applies the Pdetool tool in Matlab to solve the laminar flow of different sections in capillary flow numerically and compares the variational results and numerical results with the literature analytic solution, numerical solution and the experimental results. On the foundation of comparing the variational results, the numerical results and the literature analytic solution, numerical solution and the experimental results, we analyze the influence of the power-law index and cross-section shape on the comprehensive resistance coefficient and flow pressure relationship.

Abstract: Wave force is one of the most important environmental disturbing forces in ship motion mathematical model. Calculating the wave force in ship mathematical model is of a great importance about prediction of ships maneuverability. In order to calculate the longitudinal wave force in MMG ship motion mathematical model, the CFD method was used in this work to build numerical wave flume. The 3D model of M/V YUKUN and hexahedral mesh of the domain of the flow field were made. Software Fluent was used to simulate the motion of YUKUN in regular longitudinal waves, and the wave force acting on YUKUN was obtained. Finally, regression formula was built based on the simulation results.