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Flow in unsaturated soil or soil stimulant, under different gravity conditions is investigated using a numerical model to ascertain the extent to which the lattice Boltzmann model observed flow behavior under reduced and variable gravity conditions. The results of the simulations indicate that the bulk behavior of unsaturated flow is predicted well by lattice Boltzmann equation. For the case of an...
The thermodynamics of the exhaust gas recirculation (EGR) cooler is very important for reducing oxides of nitrogen (NOx) emission of diesel engines. Using the CFDesign software, some 3-D fluid thermodynamic models of EGR coolers are established by using the finite element method (FEM); and the temperature, velocity and pressure fields of fluids in the EGR coolers are simulated and verified by experiments...
Three dimensional fluid flow between coalescence separator plates with different shapes have been numerically simulated by the standard K-ε turbulence model in Fluent CFD. The separation characteristics of different separators have been compared. The simulated results show that the corrugated plates and the trapezoidal plates both have relatively high separation efficiency and good effects on flow...
In this paper, a numerical two-phase flow model combining with the Realizable k-ε turbulent model for compressible viscous fluid is presented for the simulation the flow around a fixed-cone valve; and the equations are solved with the finite volume method. The free fluid surface is simulated by the VOF method. The function of the fixed-cone valve for energy dissipating is pointed out by analyzing...
In this paper, the key technologies of electro-hydraulic control system to the requirements of field-bus interface, CAN-Bus application layer protocol as well as electro-hydraulic equipment protocol are introduced. The CAN-Bus hardware interface circuits, software system function and working models of a high-performance electro-hydraulic proportional valve are given. It provides the technical support...
Pulsating flow hydraulic system (PHF) which uses the vibration of oil liquid to transfer power is different from conventional hydraulic system. Because of the alternative pulsation of liquid, it's necessary to calculate the vibration characteristic such as amplitude attenuation of pulsating quantity and degree of phase lag at the output and transmission efficiency of the system exactly when the PFH...
This paper introduces an estimation method of the fluid temperature of commercial aircraft hydraulic systems. The hydraulic systems of aircraft are subjected to be investigated. Under this method, the average temperature of the fluid in the reservoir is calculated according to the flight profile. The calculating results are coincided with the actual values and reveal the varying tendency of the fluid...
The structure of the hydraulic clutch and the control fundamentals are detailed. Two control methods, the close loop control based on the feedback of engagement in unit control cycle and the pulse width modulation (PWM)-based open loop control, are presented and applied in the research for and practice of WG180 hydraulic transmissions.
With the development of the high speed and high precision machines, the linear feed drive system has been developing very fast during the last two decades. Compared with the traditional ball screw feed drive, the linear motor feed drive system eliminates all mid- transmission mechanism and exhibits the properties of high velocity, high acceleration, long stroke, fast dynamic response and etc. However,...
Predicting squeeze film damping is crucial in the design of MEMS devices. In view of the problems existing in the process of solving squeeze film damping, a multi-grid method is used to solve the squeeze film damping of micro-resonator, and a satisfying result is obtained. The multi-grid algorithm is considered having the advantage of rapid convergence and good numerical stability when solving the...
The central theme of this paper is to design a two-lane automatic antifreeze fluid sprinkler of railway coal conveyor. The structure, principle and industrial application about this sprinkler are given in detail. By means of the control of PLC, our device realizes the even, automatic, and short-range spraying of antifreeze fluid for five inside surfaces and the coal seam in the train wagon. This equipment,...
Abrasive flow processing is a new kind of surface polishing technology which is widely used for processing complex cavity parts. This paper will systematically illustrate an outline about abrasive flow technology. In addition, it also dedicated to introduce the principle of processing as well as the development & application of abrasive flow. Furthermore, based on the study of Ultra-Precision...
Because ultra-precision machining in inner surface of bend is very difficult to machine, it becomes the bottleneck of ultra-precision processing technology and is highly concerned by the domestic and foreign scholars. In order to solve the problems of ultra-precision machining in inner surface of bend, we need to find an effective method to achieve ultra-precision polishing, and reduce the inner surface...
Quasi-static squeezing process of MR fluids under different magnitudes of DC electrical current was investigated. A experiment setup was designed and fabricated to test the compression characteristics. It showed that the curves can be devided into three different regions. In the first region, the compressive stress and compressive modulus increase as the small compressive strain increases, lower than...
Environmental conservation issue advances the refrigerant substitute for the Freons. Natural working fluid must be a perfect choice. Therefore, natural friendly refrigerants R744 and R600a are selected in this research to be a binary mixture. Such a mixture can weaken their shortcomings by decreasing high heat rejection pressure as that of pure R744, and reducing flammability as that of pure R600a...
The effect of intermittent operation on the heat transfer performance of vertical U buried pipe heat exchangers is studied by method of numerical simulation and analytical solution. The calculation area is divided into two parts by the boundary of the borehole wall. For the area in the borehole, the calculation method is steady analytical solution, and for the soil area, the method is finite volume...
The calculation of pitch point in the counter flow heat exchanger used in low-temperature waste heat powered Organic Rankine cycle is investigated. Detailed calculations of a HRSG with binary mixture fluids of different composition have been done on the base of pinch point analysis. The influence of binary mixture composition on the temperature distribution in the counter flow heat recovery organic...
A new model combing numerical simulation and analytical solution is proposed for U tube ground heat exchanger with varied heat flux boundary. The calculation area is divided into two parts by the boundary of the borehole wall. For the area in the borehole and the surrounding soil area, the calculation method is steady analytical solution and finite volume method respectively. In the borehole, steady...
Using the Lagrange energy method, the dynamic equations of the soil - eccentric structure interaction system is established. By applying the linear quadratic regulator (LQR) control theory, the calculated control gain is converted to the equivalent viscous fluid damping gain using a minimum norm method (MNM). In the case of including the soil-structure interaction into consideration, the translational...
Employing a case of Ningxia TV Tower (NXTVT) as the background, the three-dimensional (3D) finite element model of NXTVT is established by resorting to SAP2000 software. The shape of NXTVT resembles a small bottom, large top, and slender-waist-middle vase. Likewise, its floors are arranged discontinuously, thus leading to the uneven distribution of the structural mass and stiffness. Hence, there is...
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