Advanced Materials Research Vols. 516-517

Abstract: Experimental investigation was performed to study the influence law of the free-stream speed, angle of attack and actuation voltage on the control effectiveness of NACA0015 airfoil stall separation suppression by steady plasma aerodynamic actuation. It is found that plasma actuation can effectively suppress flow separation on the airfoil at free-stream speeds in the range from 20 m/s up to 65 m/s. When the speed is 25m/s, the stall angle will be delayed by 3°, lift coefficient will increase and drag coefficient will decrease by 10.4% and 28.9% respectively. Moreover, Experimental results indicate that the threshold voltage increases with the increasing free-stream speed and attack angle. Meanwhile, both of smoke flow visualization and flow control experiments were carried out, conclusions show that the direction of induce flow has little effect on plasma flow control effectiveness, which means that momentum transferring is not the basic cause of active flow control of plasma aerodynamic actuation.

Abstract: This paper introduces a FEA method for vibration characteristics analysis of blade-disc structure and makes a modal analysis of a certain gas turbine blade-disc based on this method. The natural frequencies and natural modes of this blade-disc are obtained and also vibration characteristics of each natural mode and corresponding influence on gas turbine blade-disc and other components are discussed in detail. The analysis method and analysis results presented in this paper are helpful for further research on optimal design and vibration safety verification for this gas turbine blade-disc.

Abstract: The heavy quayside container crane is the key equipment of handling production in container terminal, because the general simulation system can not provide the detail information of the single crane unit during working process, this work proposed a novel method to visualize the working process of the crane. Analyzed the basic mechanisms and typical working condition, based on which, discussed the modeling method for working process visualization, and then gave the internal structure of 3D crane model. This work designed the control logic to drive the 3D graphic elements of the visualization system, implemented the working process visualization according to the working waiting list of the crane.

Abstract: The importance of fast-closed valve for mitigating accident sequent when the pipeline of the tanks stored flammable liquids discussed in this paper broken was illuminated through studying on rules and analyzing accident. And the offshore platforms and ships were as example to list the relative codes and rules force requirements on fast-closed valve. By studying the typical process easy ignored in design - leakage due to siphoning effect, and the same time some typical pipelines and fast-closed valve arrangement and the corresponding alternative measures were given. And suggested that the storage tanks stored toxic and corrosive liquid or other dangerous liquids shall install a fast-closed valve or corresponding alternative measures in its pipeline for reducing the accident consequences due to leakage.

Abstract: In order to measure average velocity of Gas-Solid Two Phase Flow in pipelines real time and accurate, to develop the gas-solid two-phase flow average velocity meter based on direct measurement method and the secondary system. The paper introduces the working principle of the system and analyzes the factors that affect the accurate measurement. To further study the performance and continuous improve its structural design, an aerodynamic testing system was established. The device performance tests were carried out. In addition, the cold and hot industrials test were carried out in the industrial field.Practical application and test results showed that the device performance is well to achieve the industrial pipeline gas-solid two-phase flow average velocity long-term, stable and accurate measurement, and measurement error <2%.It has many features: simple structure, reliability, small flow resistance, easy installation, low maintenance costs, long life, a short straight pipe required. It can measure the gas-solid two-phase flow average velocity with high or low concentrations, and suitable for round, rectangular cross-section pipe installation. The measuring device has been used in dozens of power plant boiler, and a national invention patent and significant economic and social benefits to be achieved.

Abstract: Dynamic mesh and moving wall technique were employed to simulate the unsteady flow field of moving particle with finite size. For freely moving particle, it does not come into being particle wake. Middle particle can move straightforward outlet, but left and right particles move disorderly in a restricted region. Vortex location varies with the change of particle location. Turbulence energy and pressure is decreased gradually from inlet to outlet. But for moving particle with slip velocity between gas and particle, particle wake comes into being. Turbulence enhancement by particle wake effect is studied by numerical simulation of gas turbulent flows passing over particle under various particle sizes, inlet gas velocities, gas viscosity, gas density and the distance of particles.

Abstract: Employing air at normal temperature and pressure as fluid media, the effect of twisted slice on fluid dynamics performances of fluid in cracking furnace tube was studied. The experimental results showed that boundary layer in cracking furnace tube fixed with twisted slice became thin, which leaded to the increase of heat transfer coefficient. So heat transfer was enhanced. Axial velocity distribution in central area of the tube fixed with twisted slice was smoother than that of circular tube, while velocity grad in near wall area was greater. Pressure drop increased in the tube fixed with twisted slice, whereas pressure distribution was even along axial length of the tube, in agreement with the pressure distribution in circular tube.

Abstract: The research study is aimed at the characterization of the hydrodynamics of a novel membrane-aerated reactor. Hydrodynamics was determined by means of impulse tracer trials in clean reactor and calculating residence time distribution (RTD) curves at different recirculation flow rates and hydraulic retention time. Thus the typical RTD curves were analyzed to calculate the average residence time, the dimensionless variance, the number of stirred tank reactors in series, and the dispersion number.The results showed that the hydraulic characteristics in the membrane-aerated reactor was essentially correlated with circulation rate. With the circulation velocity increasing, the number of stirred tank reactors in series decreased gradually, approaching to 1, while the dispersion number increased up to 0.2. It was concluded that the flow patterns within the membrane-aerated reactor are perfectly mixed under all the conditions tested. A simple correlation between the Reynolds number and the mixing was developed which can be used for design and scale-up purposes.

Abstract: The conflict between increasing the deposition on target and reducing off-target losses in conventional pesticide spraying is an issue. It has been confirmed that air-assisted spraying can effectively reduce the drift compared to the conventional spraying. The work presented here reports on the numerical simulation of an air-assisted boom spraying and droplets transporting process. The purpose of this study is to understand the gas and droplet two-phase flow fields and analyze the spraying distribution and droplets transporting under the different given operations of air assistance. The air-assisted spraying drift potential decreases with air-jet velocity. As the air-jet velocity is higher than 25m/s, the accretion of droplets on the upper surface of crop canopy focus on narrow areas. Air -assistance can reduce the drift of small droplets (50-200μm) effectively. In all cases, the angle between the air-jet and the nozzle is 0° or10°.

Abstract: To apply the orthogonal design to confirm the optimal combination parameter of hydraulic squeeze is one good method for the coal seam in a state of stable geological factors. But if so the effect of injection meets uncertainly the requirement of the project in pace with advancement of the hydraulic squeeze measure and changing of the geological factors.In view of this situation and the characteristic of qualitative variable as well as quantitative variable of the geological factors affecting hydraulic squeeze. Put forward the application of numerical theory on the basis of optimization study of orthogonal design to confirm the optimal combination of the technical parameters of hydraulic extrusion when geological factors is in precarious state and then proceed optimization study.