Advanced Materials Research Vols. 860-863

Abstract: The advantage and application of NH₃/CO₂ cascade refrigeration system were analyzed . The principle and composition of cascade refrigeration system were outlined . The cascade refrigeration system using NH₃ /CO₂ as refrigerant were studied theoretically and the COP were calculated .

Abstract: This research paper presents the testing results of the electricity generating from the pico hydro generator, for save in a battery 12 V. A testing of pico crossflow turbine with 0.6 m diameter of wheel and a 20 blades water turbine which has a semi-circle shape at 0.1 m diameter of blade, connected with the generator at gear up ratio of 1:3 and 1:5 respectively, was undertaken. The results from the test run of pico hydro generator by varying flow rate from 60 to 120 L/min at 0.0127, 0.0190 and 0.0254 m diameter of nozzle respectively, showed that the gear ratio between the water wheel and the generator, the diameter of nozzle and the volume flow rate are important variables that affect the electric production. A combination of water flow rate at 120 L/min, 0.0127 m diameter of nozzle and gear ratio of 1:3 gives the maximum electric power of 121.68 watts.

Abstract: In order to realize the stability-control of ultra-high pressure water jet, its kinetic characteristic should be unfolded firstly. This study measured the fluidic beam concentration (FBC) of jets discharged from six nozzles of different configurations. We also discuss flow physicals governing FBC with the help from a preliminary numerical simulation. Jet interface, the boundary line between jet and still air is like a long stepped line in the upstream, and turned to linear variation in the midstream and downstream. The characteristic of the jet can be controlled by the configuration of the nozzle exit effectively. Compared simulation results with experimental data, the conclusion can be drawn that the configurations of the nozzles have a significant influence on the vortexes which can decide the FBC.

Abstract: In the present paper, the non-intrusive Probabilistic Collocation (NIRPC) method is introduced in detail and used to simulate the effects of tip clearance uncertainty on the aerodynamic performance of NASA Rotor 37, which is combined with a commercial CFD software. The tip clearance height is supposed to be a stochastic variable in Beta distribution with four schemes of uncertainty in the random height of the plain tip clearance, the leading edge, the trailing edge and both the leading and trailing edges, respectively. The statistical properties of total performance of the rotor and flow structure within the blade passage in different flow conditions are analyzed. The results show that the Std. of total performances caused by the uncertain plain tip clearance decreases with reducing of the outlet pressure. The maximum of the standard deviation of Mach number appears in the regions where the leakage flow, the shock wave and the separation flow locate, which decreases from the tip to the hub. When the tip clearance is linear distributed, the uncertainty of tip clearance height at the leading edge is the main factor under high mass flow conditions. With the mass flow reaches to choking point, the Std. of total performances caused by the uncertainty of tip clearance height at the trailing edge drops sharply.

Abstract: The magnetic fluids are assumed non-conductive with few free electrons existing, then the boundary layer equations are obtained for two special non-conductive ferromagnetic fluids, i.e. non-conductive Poiseuille flow and Couette flow, and the velocity distribution are found to be parabolic.

Abstract: The parameter selection problem of kernel function in support vector machine directly affects the generalization ability of support vector machine model .In order to improve the accuracy of the fault classification of centrifugal fan ,the classification method based the Drosophila algorithm optimizes least square support vector machine is proposed In this paper .First, it uses the eigenvectors based on the fan vibration frequency domain as learning samples .Then it uses the improved least square support vector machine model to recognise the patten of the energy feature of fan vibration signal .This article also uses the particle swarm and ant colony algorithm to optimize least square support vector machine .The simulation results show that the method of least square support vector machine based on Drosophila optimization has the advantages of high recognition rate and high diagnostic speed .And the method is feasible and effective.

Abstract: The badminton wind tunnel experiment quality classification was influenced by a lot of factors, such as the size of the wind tunnel wind speed Settings, the selection of the wind hole diameter size, Experiment parameter Settings of the test system software used standard and experimental error and so on. Therefore, a factorys wind tunnel experimental facility would be used by this paper, in order to make the quality of badminton, wind tunnel wind speed and wind hole diameter are researched further. Through the experiment testing, and combined with badminton wind tunnel experiment of theory knowledge, get the impact of these factors on the quality of badminton classification rule. Theoretical analysis is the same as the result of experiment, which this conclusion is indicated by the experiment that what we do. So as to choose the right wind tunnel device and system software of the test parameters Settings provide certain reference. Also the Badminton the judgment of the quality grade classification standard was provided the important reference frame by it.

Abstract: There are many difficulties to design, processing and research on numerical simulation for Francis turbine because of the complexity of blade shape and the difficulty of solid modeling. Based on two-dimensional wooden patterns of Francis turbine blades, this article aims to complete blades three-dimensional modeling for Francis turbine runner with long and short blades by means of Pro-E software which has powerful 3D modeling function. After comparing three kinds of available methods to generate blade across section which provided by Pro-E, finally completed blades three-dimensional modeling by method of generating across section with point files, established a smooth and accurate three-dimensional model. The method provides an accurate physical model for the numerical simulation of the Francis turbine with long and short blades, as well as provides a feasible approach for hydro-mechanical blades modeling.

Abstract: Establish simulation model based on BP neural network PID control to solve the issue of hydro-viscous drive speed regulating start control strategies, experimental verifications prove its adaptability through AMESim/MATLAB co-simulation, research shows that: BP neural network PID control for hydro-viscous drive has a good self-correcting effect, the output speed adjusts towards the opposite direction according to the error and the error rate, while maintaining the smoothness of the output curve, thereby it can avoid over-large mechanical shocks, it indicates the BP neural network PID control is suitable for speed regulating start.

Abstract: The theoretical model of weakly compressible coupling water hammer was established and a FSI program code was developed for coupled weakly compressible water with penstock movement. It combines the weakly compressible water source CFD code and FEM shell element code. The shell element based on orthogonal curvilinear coordinates was completed in FEAP. Meanwhile, the turbulence model in OpenFoam class library was called by using object-oriented technology. This code takes into account both the weak compressibility of water and fluid turbulence characteristics. Using this code, a fluid structure interaction analysis with water hammer was completed. The numerical results agree well with the field test results.