Applied Mechanics and Materials Vols. 212-213

Abstract: In this paper, we adopt theoretical method to study the evolution characteristic of the two dimensional turbulent vortex structures in a meander channel. The disturbance growth rates under different bank curvatures are simulated. The result showed that the change of growth rate of smaller vortices is more intensive than bigger vortices. Future more, we consider the coherent vortex structure as a kind of disturbance to study the evolution characteristics of multi-scale turbulent structures in a meander channel, make basis for finding “meander channel-forming vortices” which is controlling the river shape and adapt to the meander river in theoretic.

Abstract: This study uses SMS-2D unsteady flow model to simulate apron setting and discuss its scour protection due to bow wave around the bridge pier on the main deep trough of 24-pier ChihShang Bridge and 3-pier Taitung Bridge in 100 years return flood peak flow, on the downstream BeiNan River in East-Taiwan as case study. Further, the topic of this study is to evaluate location-oriented scour likely result in accelerated erosion of critical piers by apron setting designed sizes in case of excessive cost, thus, providing reliable information and references for bridge engineers.

Abstract: Based on AutoCAD 2010, Visual C++. NET 2008 and ObjectARX 2010 the hydraulic design software of pump suction chambers, called PXSS, was successfully developed. The PXSS could design all kinds of pump suction chambers. Key technologies in the development process of software PXSS were introduced. A pipeline pump suction chamber and a spiral-shaped suction chamber were designed with the PXSS software. The two examples show that the PXSS can realize the parametric drawing of the pump suction chamber and improved the efficiency of the design staffs. So, it could be applied to engineering practice.

Abstract: Based on CFD software Fluent, the flow field of screen filter was simulated numerically，and the results of calculation were analyzed in detailed. The results show that the velocity distribution declines along the radial direction of tank. The flow can be rotated and mixed in tank, and the screen of outlet can be clogged quickly resulting in uneven clogging. The turbulent pressure distribution of filter is not uniformity. In the inlet, the turbulent energy is larger than the second tank. In the inlet of second screen, there is a high turbulence region resulting in the larger head loss. The pressure distribution of the second tank is uniformity in the course of filter work. However, the pressure of the first tank is significantly higher than the second one.

Abstract: This article introduced the principle of high speed hydraulic compactor application in the backfill of bridge platform and its advantages. At the same time, the example is analyzed with the high speed hydraulic compactor treated the soil, which is backfilled in the bridge platform. The result shows that the high speed hydraulic compactor can effectively reinforce the bridge platform soil backfilled, which can reduce the settlement and the bridge platform jump after opening to traffic.

Abstract: Shallow wake patterns are investigated by numerical method based on the solutions of two-dimensional (2D) shallow water equations and three-dimensional (3D) Reynolds-Averaged Navier-Stokes (RANS) equations with the implicit scheme on collocated mesh in the FVM framework. The analysis are made on vorticity contour distribution, transverse velocity (uy) variation with time, Strouhal number (St) and time-averaged longitudinal velocity (ux) to verify the characteristics of shallow wakes behind cylinder. We compare the numerical results with Chen’s experiment very well and show the capability and difference of 2D model and 3D model in modeling shallow wake structure. The results show that the 2D model predicts the vortex street (VS) wake well, yet the 3D model is fit for the steady bubble (SB) wake. The 2D model performs more accurately when VS wake transforms to unsteady bubble (UB) wake, while the 3D model is better when UB wake transforms to SB wake.

Abstract: The float motion mathematical model is established based on the theory of flow around a body in this paper, by solving the mathematic model with special method, the integrity form flow equation of rotameter is derived, and float stability and motion characteristics are analyzed.

Abstract: For the operational optimization issues of the parallel pumping stations, on the two aspects, the multi-pump station and the parallel pumping stations, the solutions to the constructed models are illustrated, and a few key issues of the model solution process are described. Therefore, while providing a few new methods to construct and to solve the models, the optimization methods of large scale system is enriched and developed.

Abstract: The hydro turbine governing system framework model include hydro turbine , conduit system,governor, generator and load was established in which the typical PID and the new improved PID controller in governor respectively used. The sensitivity of the governing system for system parameter was deduced.The robustness of the governing system used typical PID and improved PID was discussed and analyzed. The conclusion is illustrated by simulation results.

Abstract: The hydro turbine generating sets model exists uncertainty in structure and parameters due to its complex structure and operating states multiformity. Especially, the adaptability and robustness of controller is more important for the stabilization control at equilibrium point under given output. Based on Hamiltonian control model of nonlinear hydro turbine generating sets, the L2 disturbance attenuation control is added into the stabilization control to restrain disturbance from model and structure parameters in this paper. The L2 additional control is proved to be asymptotic stability, and its control low is derived. Simulation results show that adding L2 additional control, system can stable to given equilibrium point and has more adaptability and robustness.