Applied Mechanics and Materials Vols. 397-400

Abstract: Liquid sloshing is the source of disturbance. General the equivalent mechanical models are used to simulate the liquid sloshing in container. In this paper, the equivalent pendulum model for liquid sloshing is established. Further, the parameter relationship between the equivalent spring-mass model and equivalent pendulum model is presented. Then, parameter determination process of the equivalent mechanical model is proposed. Finally, a numerical example is implemented to calculate the parameters of equivalent model for liquid sloshing in a container.

Abstract: Based on the theory of gas-solid two-phase flow, abrasive flows in ceramic nozzles with different structures are simulated by FLUENT software and the outflow velocity of particles is compared. The results show: the abrasive outflow velocity of ceramic nozzle with cone angle is large than that of ceramic nozzle with through-hole structure, and the distribution of abrasive particles is more uniform for the ceramic nozzle with cone angle. The best entrance cone angle of ceramic nozzle is 10o30o, and the maximum abrasive outflow velocity of the ceramic nozzle with cone angle of 20o is 90.16 m/s. The simulation results have a good agreement with the experimental results.

Abstract: The paper introduce structured grid division, use CFD numerical simulation and FLUNET software to conduct the simulation calculation for the hinge moment of rudder. To illustrate the problem, we select two unused plane airfoil An axis-symmetric rudder, one for the special design of the plane rudder. Calculated at 0.4 ~ 1.8Ma, different rudder angle, angle of attack different hinge moment value, and compare them ultimately come to a flat airfoil optimization program, making the steering hinge moment to meet the indicators proposed.

Abstract: Flow path is one of the key components of drip irrigation emitter. Four factors of fractal flow path section area, length, tooth highness and tooth number are interosculated nearly each other, and the influencing process of flow path to hydraulic performance parameters was analyzed with path analysis. The section area and length of the flow path were the main factor affecting on the flow exponent and flow coefficient of drip irrigation emitter, and other ones less. Reducing the section area could debase the emitter flow exponent, and reducing section area and increasing the length of fractal flow path could debase the flow coefficient.

Abstract: The semi-elliptic cylinder shell vortex generator set in the interpolation-tubular air pre-heater was studied. And by changing the high-width Ratio v, dip angle α, attack angle β, spacing s of vortex generator to research the heat transfer and resistance properties under different working conditions, and the optimization structure of vortex generator was determined. The heating medium of the air pre-heater is the flue gas that passes across tube outside, and the cooling air as the cooling medium in the tube longitudinal scoured. The Reynolds number range is 25000 ~ 40000. The research shows that: semi-elliptic cylinder vortex generator can obviously improve the heat transfer performance, the optimization structure of the semi-elliptic cylinder vortex generator: high-width ratio v = 0.45, attack angle β = 65 °, dip angle α = 15 °, span s = 90 mm, the heat transfer enhancement comprehensive effect raised about 43.2%~72.6%.

Abstract: The dynamic measurement of the high pressure side flow in hydraulic system is still one of the important and difficult problems in hydraulic test technique. Based on the method of bypass flow measuring principle, the distribution relationship between main and branch pipe flow should to be solved in digital simulation, and the corresponding numerical analysis was carried out on the result data of analysis. From the results of numerical analysis, the flow distribution relationship between main and branch pipe were found, and the corresponding approximate numerical expressions were obtained.

Abstract: A new synthetic pilot pressure positive flow control system used in excavator was proposed in this paper, The mathematical models of this system and the positive control system were established, the transfer functions from the displacements of the regulating pressure springs to the operating cylinder piston, and the rotational angle of the right walking motor were deduced. The output power curves of these two control systems were acquired using AMEsim. The simulation results show that the synthesis pilot pressure positive flow control system is more stable and has higher power utilization rate to the traditional positive control system used in excavator. The new control system provides an new design method of energy-saving excavator control system.

Abstract: With the heightened concern for renewable energy because of significant energy problems, the interest on wind energy has been greatly increased. In this study, 4 kinds of RANS turbulence models were compared and discussed based on developed analysis model. At first, a numerical model for 1kW wind turbine blade was constructed. In the following step, Spalart-Allmaras, standard k-ε, RNG k-ε and Reynolds Stress turbulence models were candidated for comparison. The analysis results show that standard k-ε or RNG k-ε model is relatively good selection under the condition of considering accuracy and computational effort simultaneously. The developed analysis model and simulation results have made a theoretical basis for improving the simulation accuracy of wind turbine blade with minimum computational effort.

Abstract: Horizontal well and hydraulic fracturing are the main technologies for shale gas development. The desorption properties of shales are very important data for shale gas development. In order to simulate the desorption process in shales with horizontal well and fractures, a new method for shale sample preparation and a new experimental system for the evaluation were developed. The effect of the number and half-length of fractures on the desorption rate and the desorption equilibrium time were measured when the system pressure drops from 9.2MPa to 7MPa. Experiments show that the initial desorption rate increases and the equilibrium time decreases with the increase of the number and half-length of fractures. Within the scope of the experiments, the number of fractures is more important than the half-length of fractures for the desorption rate.

Abstract: Establish valve stem leakage flow channel model, apply the CFD numerical simulation the internal flow field and noise. Research shows that it is no effect on the valve inlet and outlet flow field when the valve stem leakage. It is no effect on the valve body flow field and the greatest influence the balance cavity flow field. Changing the flow direction of the balance cavity and produce left vortex, it break left vortex of right part. New tremendous noise sources appear the balance cavity and improve the noise of surrounding areas.