Applied Mechanics and Materials Vols. 336-338

Abstract: Euler-Euler two-fluid model was used to construct control equations of gas-solid two-phase flow, based on SIMPLE algorithm of collocated grid and FLUENT software, the pressure distribution of air-flowing field and dust field diffusion in fully-mechanized excavation face with different air-draft volume were simulated. The results show that with the increase of exhausted dust ability, diffusion intensity of producing dust pollution in driving head constantly decreases. Compared to air-draft volume of 320m³/min, when it is 600m³/min, the average dust concentration at the driver and whole section positions respectively decrease 51.28% and 56.51%, and high-concentration dust diffusion distance of the other workers position section decrease from 13.6m to 8.5m. Engineering Application indicates that the measured dust concentration is basically anastomosed with simulation result. When air-draft volume of dedusting fan is 600m³/min and dust control system with air curtain formed by forced fan drum is used, the dedusting rates of total coal dust and respirable dust on spot are respectively 95.1% and 96.1%, which achieves a great dedusting effect.

Abstract: Multifunctional sting support system at high angle of attack is the main way of support for aircraft test in 8m×6m wind tunnel. In recent five years, a series of supporting facility has been developed to improve test efficiency and enhance the finer testing and measuring capability. New developed vibration suppression system can not only enlarge the maximum weight-bearing of the support mechanism, but also reduced the vibratory frequency of a model. Power (motor) control system was modified to adapt to the requirement of 0.2% precision. TG1801 balances were designed and manufactured with high precision and good stiffness. A remote control unit has been applied for a specific aircraft test as model facility to reduce labor intensity and raise test efficiency. Aircraft test efficiency in 8m×6m wind tunnel has been increased gradually and data accuracy reaches the advanced international level through these improvements.

Abstract: It is known that turbulence intensity will affect on power performance and Annual Energy Production (AEP) of wind turbine. But it is unknown how big the influence is. The article quantifies the concrete influence by testing. After calculating the output of wind turbine in different turbulence intensity level, it has shown that the more intensive turbulence will lead more negative impact on the output of wind turbine. The investigation provides some basis for the site sitting of wind farm.

Abstract: Based on the model of circle involute scroll channel, a following coordinates was built, mathematical model was established in the coordinates. On the basis of the four basic assumptions, equations of motion for the flow field inside the involute channel was described under the N-S equations, and the boundary conditions for the model was analyzed. This paper explores the flow field inside the involute channel.

Abstract: The conveying logistics of harvesting harvesters has been one of the constraints to the sugarcane harvester technology development bottleneck problem,which conveying stability and reliability are not high and easy to plug. Firstly, the mechanism of logistics conveying was discussed. Secondly, for the sugarcane flows (SF) changing in sugarcane harvester process as the objects, the sugarcane volume model and mass of the model in a static state were established, which was relation to the number, the form and the parallel. Finally, the experiments had been done to verify the model coefficients. It had provided the theoretical basis for increasing the sugarcane harvester smooth conveying and work efficiency

Abstract: Energy conversion from rotational to thermal is investigated for a compressible ideal gas. The high speed rotation is considered as the driven force of the isentropic compression. The analytical model explaining the thermodynamic parameters (pressure, pressure gradient, density, and especially temperature) are developed. The analytical results are compared with the simulation data obtained from Finite Element Analysis, which employs compressible Navier-Stokes equations and heat equation. A good accordance between the analytical and FEA results has been observed. And it shows a predictable beginning and end state for the isentropic rotation process.

Abstract: Removed at authors request

Abstract: Dedicated to the disadvantage of variable-speed drive, the energy regulation based variable-speed electrohydraulic drive is proposed. It is a novel solution by adding an energy regulation device and a flow valve into the system. It combines the advantages of variable-speed drive, valve control and energy regulation. But it is a multiple-input multiple-output control system, coupled with strong nonlinear, volatility and uncertainty of some parameters, which make the control strategy complicated. The multiple-compound PID control strategy, as well as the parameter tuning rule, is proposed.

Abstract: Seawater hydraulic pump, of which the performances and service life are highly dependent on the structural design and material selection of the friction pairs and sliding bearing, are the power componentof the seawater hydraulic systems. Based on the previous studies, a seawater abrasion and friction test bench with high ambient pressure (≧20MPa) is to be developed for deep-sea (≧2000m) application environments. The technical requirements are presented and comparison analyses have been made between two testing schemes: rotating cylinder-blockscheme and rotating swash-plate scheme. Details are presented on the designs of the three key friction pairs and sliding bearing of the rotating cylinder-block bench. This research provides a test bench for the design of key parts in deep-sea water hydraulic pump/motor and the studies of the related theories (such as the friction and wear theory, lubrication and bearing mechanism).

Abstract: As an important equipment of electrohydraulic lifting system, heavy-duty cylinder uses asymmetric structure, i.e., non-rod chamber and rod chamber of single-rod piston cylinder. The kind of structure do not ensure equal flow rate between non-rod chamber and rod chamber, leads to different control parameters (including flow gain) on extending and retracting movement of cylinder, and arise asymmetric dynamics. Based on the new definitions of load pressure and load flow, mathematic models of asymmetric hydraulic cylinder on extending and retracting direction are established. Simulation results indicate that the overshoot of extending speed is larger than that of retracting speed, and exists asymmetric features on two moving direction.