Applied Mechanics and Materials Vols. 66-68

Abstract: A numerical investigation in the CFD method of the heat transfer characteristics and the self-sustained oscillation flow is conducted in a grooved channel with periodic mounted inclined plate.Control of low Reynolds number range(600-1600), two-dimensional, unsteady laminar flow was analyzed .Various physical and flow arrangements have been considered as plate length, plate position and Reynolds number .A comparison among different channels was made for streamlines、history of cartesian velocity component in the x-direction and Nusselt number(Nu)．Compared with the results got by the no plates case, the heat transfer has been enhanced in channel that installation of a inlined plate for all Reynolds number.At higher Reynolds number(Reynolds number over the critical Reynolds number), the enhancement of heat transfer is more marked ,that because it can not only modify the direction of the flow towards the obstacle faces to be cooled ,and activate the self-oscillations using inclined plates placed periodically.

Abstract: Experimental investigation results of the fuel nozzle group in a heavy-duty gas turbine are presented. Atomization characteristic has great impact about combustion efficiency, ignition performance, and outlet temperature field of combustor. Obtained atomization characteristic about spray particle size and distribution using LDV/PDPA system. These experimental data have provided reliable basis for the nozzle group design, development and operation.

Abstract: Study of experiment system and experimental investigation results of the group nozzles in a heavy-duty gas turbine are expatiated. In order to measure gas flows of every flow branch in the group nozzles, flow meter of type SH-1 is specifically developed, The measure system, control system, data display system, data acquisition analysis system subtly combine, the SH-1 gas flow test equipment and these measured flows data are precise, stable, good reproducibility, the errors of the measuring are less 0.5%. Using SH-1 flow meter, gas flows of Ⅲ,Ⅳ,Ⅴbranches are precisely measured, the combustion testing of the group nozzles in the flame tube is made, its performance is satisfied with the design requirements, these demonstrate: the testing results by using SH-1 flowmeter are reliable, stable.

Abstract: Large investments have already been made in Europe and the US through R&T programmes and collaborations to reduce the negative environmental effects of aircraft use. Research is therefore providing the technologies to improve the performance of existing engine components. The main objective of the paper is to evaluate the potential of reducing the environmental impact of civil subsonic aviation by using hydrogen fuel. Looking at the prospect of alternative fuels, synthetic kerosene produced from biomass turns out to be feasible and offers environmental benefits in the short run, whereas hydrogen seems to be the more attractive alternative in the long run. Powering aero engines and aircraft with hydrogen has been done successfully on a number of occasions in the past.

Abstract: The increase, in recent years, in the size and efficiency of gas turbines burning natural gas in combined cycle has occurred against a background of tightening environmental legislation on the emission of nitrogen oxides. The higher turbine entry temperatures required for efficiency improvement tend to increase NO_X production. To reduce NO_X emissions, new engine core configurations with heat management and active systems, as well as advanced combustor technology, have to be investigated. This paper reviews the various approaches adopted by the main gas turbine manufacturers which are achieving low levels of NO_X emission from natural gas combustion.

Abstract: This paper proposed a new method to detect the damage of composite skin/stringer panel structure using modal strain energy combined with neural network. The change ratio of element modal strain energy is choosen as damage indicator because of it’s highly sensitivity to the location and severity of structure damage. Neural network here play the role of a tool to indentity the damage according to the change ratio of modal strain energy. To achive this, a three layers neural network model is built and the BP arithmetic is used. The proposed method is validated using a numerical simulation of a composite skin/stringer panel with damages in some elements of its FEM mode, which are simulated by reducing elements’ material stiffness properties. The result shows that, this method is robust, accurate and highly efficient with the maximal error limited in 10%.

Abstract: Underwater vehicle plays an important role in ocean engineering. Depth control by fin is one of the difficulties for underwater vehicle in motion control. Depth control is indirect due to the freedom coupling between trim and axial motion. It is included the method of dynamic analysis and lift-resistance-coefficient experiment and theory algorithm. Considering the current speed and depth deviation, comprehensive interpretation is used in object-planning instruction. Expected depth is transformed into expected trim. Dynamic output fluctuation can be avoided, which is caused by linear mapping of deviation. It is steady and accurate for the motion of controlled underwater vehicle. The feasibility and efficiency are testified in the pool and natural area for experiments.

Abstract: Long-span suspension bridges, due to their flexibility and lightness, are much prone to the wind loads, aerodynamics performance has become an important aspect of the design of long-span suspension bridges. In this study, the static wind load acting on the suspension bridge during erection has been investigated through wind tunnel test and numerical analysis. The wind tunnel test was performed using a 1:50 scale section model of the bridge, the static wind load acting on the section model was measured with varying attack angles. Numerical method used here was computational fluid dynamics simulation, a two-dimensional model is adopted in the first stage of the analysis, then the SIMPLE algorithm was employed to solve the governing equations. The analytical results were compared with the wind tunnel test data, it was shown from the study that the results of CFD simulation was good agreement with that of the wind tunnel test.

Abstract: For the intermediate pylons of multi-pylon cable-stayed bridges can’t be connected by backstays to fixed points, it is possible to produce greater horizontal displacements in the top of towers under the action of external loads. Therefore, it is an important problem to obtain adequate structural stiffness in the design of multi-pylon cable-stayed bridges. In this paper, methods of improving stiffness of multi-pylon cable-stayed bridges are discussed. Multi-pylon cable-stayed bridges with intersecting cable are studied. Some useful recommendations were given for the design of multi-pylon cable- stayed bridges by numerical calculation.

Abstract: A crane’s online safety assessment system is introduced in this paper, which adopted the 3-tiers structure, dotnet and sql technology. The system implemented the hazard risk identification, risk assessment publishing, publicity function of safety culture, rights management, and system maintenance. The system is running smoothly which verified that the designing method is effective and feasible.