Advanced Materials Research Vols. 542-543

Abstract: This study reports a numerical CFD study concerning the effect of frost thickness on the heat transfer performance of a vertical pipe. Simulation are made under various variables affecting the frost growth such as outer flowing air conditions (temperature, flow velocity, humidity) and inner flow conditions of cryogenic fluid. The frost growth is mainly associated with the outer conditions. The frost thermal conductivity could play an important role in the froth growth. There is no great. The simulation for frost formation carried out with coupling to a commercial CFD code(CFX). The CFD simulation offers the possibility to predict frost formation within vertical geometries. The frost formation is based on the Lewis analogy of heat and mass transfer and it is embedded with CFX. The vertical surface temperature of the freezing body is determined by fluid structure interactive error method.

Abstract: The manifolds are flow distribution devices commonly used in the heating furnaces, heat exchangers, reactors, boilers, and so on. The flow distribution uniformity in the manifolds, to a large extent, decides the operation safety and economy of these devices. Manifolds are consisted of a number of T-type pipes, the flow characteristics in the T-type pipe takes an important role in the flow distribution non-uniformity of manifolds, so flow characteristics in T-type pipes were systematically researched and analyzed by the Fluent simulation software in this paper, exploring the influencing factors such as the inlet mass flow rate on flow distribution non-uniformity, and providing some measures to improve the flow distribution uniformity.

Abstract: Using triethanolamine, vegetable fatty acid, alkyl polyoxyethylene alkyl ether sulfuric acid ester and dimethyl sulfate as raw materials, a new kind of anti-balling additive for drilling engineering (WORB) was synthesized. The wetting property and anti-balling performance of WORB were investigated according to the experiments of wettability, surface tension and absorption effect. The results indicate that the adsorption of WORB on the surface of the cuttings is monolayer adsorption, which can avoid repeated cutting caused by the agglomeration of cuttings. WORB can alter the wettability of rock surface and the inner pores of the rock to reduce the surface tension of the rocks. Moreover, WORB can form multilayer chemical and physical adsorption on the surface of drill bits and BHA in the form of oriented adsorption of organic phosphine.

Abstract: In this article, we use the porosity to express the effective stress of rock mass, and get the equilibrium differential equation. on this basis, using equivalent continuum model and the finite element method to simulate the degree of coupling. In full consideration the interaction between groundwater and the rock framework and referring to the underground water solid coupling seepage flow mathematic model, based on finite element theory, we obtain the calculation method and the coupling method. These methods can real simulate groundwater seepage condition and have a great significance.

Abstract: Bidirectional hydraulic lock is a key component of hydraulic system of the truck crane[1]. By using Fluent software, this paper simulates and analyses the hydraulic clamping phenomenon, which happens in the truck crane outrigger bidirectional hydraulic lock's spool in the case of taper exists, as well as the center lines of spool and valve sleeve are eccentric, and the effect of different kinds of pressure-equalizing grooves on hydraulic clamping force, then concludes that the number, the shape and the size of pressure-equalizing grooves, and whether pressure-equalizing grooves are concentric can take effect on clamping force, thus a new way is prompted to improve the structure of bidirectional hydraulic lock.

Abstract: In this paper, influence of the outlet aperture of sensitive chamber on the stability of fluidic gyroscope has been studied. Using ANSYS-FLOTRAN CFD software, the finite element simulation was conducted by a series of procedures, such as two-dimensional model building of fluidic gyro, meshing, loads applying and equation solving, we calculated the airflow distribution in sensitive chamber of fluidic gyro with different outlet apertures. The results show that the airflow would decay and diffuse after it injects into the chamber through nozzle, the bigger the outlet aperture, the smaller the pressure in the outlet-side and the airflow velocity discharged from the outlet, and the more seriously the airflow decay and spread. An effective way to improve the stability and structural optimization of the fluidic gyro output has been studied in this paper.

Abstract: The way of dry-mixed mortar air-sliding has many advantages，such as improving transport efficiency, ensuring cement quality. But, dry-mixed mortar air-sliding may occur segregate, this phenomenon serious break the original ratio of cement, risking quality of cement[2]. This article suggested a new model of discharge opening with multi-holes, this model can allow dry-mixed mortar flow out at different height, and control the rate of flux in each port to keep mortar equally, this model eliminated the non uniforms caused by different height, eliminated the affection of segregate, ensure the quality of the cement.

Abstract: The pressure drop transfer standard is a major measurement element in the pressure drop measurement device as a traceability element. This paper analyzed the air flow in the capillary tubes, and mathematical model of pressure drop transfer standard was got by the differential pressure at inlet non-laminar flow part and differential pressure in the laminar flow part. A CFD method adopting laminar model is used to confirm the theory. The pressure drop value was calculated by the diameters and length of all capillary tubes measured by OGP video measuring systems, and the result shows the calculated value was verified by the calibration value.

Abstract: The initial seepage field analysis is prerequisite and important content for the water-tight underground cavern design. Although the field water pressure test can provide a more accurate isotropic permeability coefficient，which does not reflect the anisotropy permeability of jointed rock mass.Based on joins network simulation technique，a new method for calculating the anisotropy permeability is proposed. Different sizes are generated with the programming language FISH embedded within 3DEC. The values of joint geometric characters and number of random joints in each group are decided through the derivable formulas. Principal value and characteristic vector of permeability tensor are easily calculated with Matlab software. Considering the space orthotropic permeability coefficient，the initial seepage inversion is completed with the fl_anisotropic model，the Fl_anisotropic model parameters are obtained from principal value and characteristic vector of permeability tensor. The inversion analysis provides initial seepage field for water-tight underground cavern water curtain design and stability analysis.

Abstract: This paper reports numerical simulations of fluid mixing in a rotating microchannel with a microchamber fabricated on a CD-like substrate. The sample fluids are driven by the centrifugal force and brought in contact at a Y-shaped junction, and then the mixing flow moves through a straight channel with a circular chamber where the main course of mixing takes place. The CD-like micromixer is rotated clockwise at speeds ranging from 300 to1200 rpm. With increasing rotational speed, the mixing efficiency is found dropping in the lower range (≤ 540 rpm), where the diffusion still dominates the mixing, and then grows progressively to reach as much as 90%. The progressively growth in the higher speed range significantly improves the slightly descending and flat distribution for a straight mixing channel without a circular chamber. This significant enhancement of mixing is due mainly to the vortices generated in the circular chamber and the strong transverse flow induced by the Coriolis force.