摘要: Based on the application of the present Underwater Aeration Machine in Environment Field , this paper made an analysis of the situation of the Underwater Aeration Machine at Home and Abroad. Several main Problems were raised in running process .Based on the practical problems and then designing a new structurea Underwater Aeration Machine and a corresponding control scheme, each of these problems is further discussed and explained in order to point out the research field for the development of Underwater Aeration Machine later.This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.
摘要: This paper analyses quantitatively mechanism that hydraulic turbine runner blade tail produces Carmen vortex column, and the blade hydraulic elastic vibration which is produced by Carmen vortex column, also analyses the harms of blade hydraulic resonance, puts forward corresponding preventative measures. For the stable operation of large Francis hydraulic turbine, these measures have reference meaning.
摘要: This paper studies the effect of vortex generators on hydro-turbine working performances. The study was carried out on a hydro-turbine system provided by Waterpumps Oy, Finland. First, the performance of the hydro-turbine system was analyzed with a CFD solver under different working conditions. Then, the hydro-turbine performance was examined with several vortex generators installed uniformly on the inside wall of the draft tube near its inlet. The turbine system’s efficiencies were compared for cases with and without vortex generators. Results show that turbine performs better when there are vortex generators installed in the draft tube of which the pressure recovery factor is much higher.
摘要: The paper analyzes the status of acrylic filtration and describes a new filter, named KKF18, which filter viscose fiber. According to compare the parameters of acrylic solution fiber with viscose fiber’s and simulate by Polyflow, the results show that the KKF18 can be used in acrylic solution fiber. Then the paper builds mathematical model of acrylic liquid flow in cylindrical hole and conical hole, which belongs to KKF18.Using Polyflow to simulate respectively acrylic liquid flow in those hole, the results not only verify the correctness of the mathematical model ,but also illuminate the local pressure of cylindrical hole is smaller than conical hole. So cylindrical hole is more suitable for acrylic filter.
摘要: In this paper, the performance parameters of time-average basic performance equation of pulsed liquid jet pump are studied in numerical methods. The change rules and its influence on performance of throat tube inlet function are quantitatively analyzed. The conclusion is obtained that pulsed jet could mainly make fluid of throat tube outlet more fully mixed and better improve optimal working parameters of liquid jet pump. Also, change rules of throat tube inlet function show the increasing of the entrainment rate is the reason why pulsed liquid jet pump could improve performance.
摘要: This paper presents a computational fluid-structure dynamics coupling method of flexible wing. The computational fluid dynamics is solving RANS equations. The stiffness used in computational structure dynamics is tested by experiments. Then the aerodynamic performance of flexible wing is researched and compared with rigid wing. The results show that the lift and thrust generated by flexible wing are less than the rigid wing. Flexible wing can slower the variety of aerodynamic performance when the flight environment is changing. And flexible wing has bigger stalling angle.
摘要: Choose the appropriate rear shroud diameter of impeller could get relatively small axial force and high pump performance. In this paper, a deep-well centrifugal pump impeller with a small rear shroud was studied by simulation and test. Two stages deep well centrifugal pump was simulated by means of a commercial CFD software that solved the Navier-Stokes equations for three-dimensional steady flow. The flow field and the static pressure distribution in the impellers obtained by steady numerical simulation were analyzed. By manufacturing and testing, the test results was acquired, and then compared with the predicting data of the numerical simulation. Results show that trimming the rear shroud could reduce the axial force, but too small rear shroud diameter lead to pump performance decline.
摘要: In the continuous galvanizing line, gas knives are used to control the liquid coating thickness. They are based on the principle of turbulent planar impinging jet. The CFD (Computational Fluid Dynamics) method is used to research the turbulent planar impinging jet of gas knives. With the implement of FLUENT software, the realizable k-ε model is adopted to simulate the pressure field. The transverse impact pressure distributions on the steel strip are demonstrated. For gas knives with even nozzle slot, the plot of impact pressure is analogous to parabola, reducing from middle to two ends. This numerical result shows agreement with experimental one. It indicates that the realizable k-ε model can accurately predict the impinging jet. Besides, for gas knives with uneven nozzle slot, the impact pressure is basically equivalent. Furthermore, several main factors having effect on the coating thickness are studied. The numerical results reveal that, the higher the inlet pressure, the thinner the coating; and the longer the distance between jet and strip, the thicker the coating.
摘要: The characteristics and research actuality on mixed flow pumps are introduced simplely. A mixed flow pump with volute as diffusion part is designed and its specific speed is 556.8. The axial velocity circulation and blade angle variety with linearity distribution are used to deisign the impeller. The fixed diffeuser between impeller and volute is deigned by arc airfoil.The cross sections of volute are all asymmetry. The commercial code FLUENT is applied to simulate the inner flow in the mixed flow pump and its energy characteristics are predicted according to the simulation results. The inner flow analysis indicates that the flow in the pump is good and the characteristic prediction shows that the pump performance can meet the design demand. The experiment test of the pump are done. When the blade angle is about 0°, the maximum efficiency of the pump is up to 85.76% and the actual efficiency at design point is about 3% higher than demand efficiency. The study fruits can instruct the hydraulic design of higher specific speed mixed flow pump with volute as diffusion part.
摘要: Lift makes a vehicle in air and thrust makes advancing. The lift of flapping wing air vehicle is composed of two main parts, flapping lift and advancing lift. The advancing lift of flapping-wing is similar as of fixed-wing, generated mainly by relative velocity and angle of attack. The flapping lift is owned only by flapping wing. The flapping lift is generated by asymmetry flapping motion manner of wings, asymmetry airfoil, and asymmetry folding in flapping cycle, accordingly leading-edge vortex and wake capture effect. The thrust is completely generated by flapping wing and the magnitude of thrust is mainly controlled by flapping frequency and flapping manner. The flapping motion is a thrust generator and lift enhancing manner. Flapping wing air vehicle will be one of the star members of man-made air vehicles.