【正文】 d n ranges from to depending on test conditions. Particle impact angle is another important factor for erosion. Finnie (1972) derived the angle function from the equation of motion for a rigid abrasive particle striking a ductile surface. For aluminum alloys, the model shows the maximum erosion occurs at 13 degrees and decreases to zero at 0 and 90 degrees. This angle function is in good agreement with experimental data except for high impact angles. As a reason for the discrepancy between measurements and the model, Finnie states that the erosion mechanism at high angles is very different from the one at low angles. At low angles, erosion is mostly due to the cutting mechanism while at high angles, it is due to the surface roughening and low cycle fatigue fracture. Figure shows the function f ( θ) for typical ductile and brittle materials. Particle properties also greatly affect the erosion of ductile material. For example, differences in angularity of particle shape can cause different erosion mechanisms which yield different erosion rates. Winter and Hutchings (1974) studied the effect of particle orientation at the impact surface. Erosion measurements on mild steel and lead were performed using flatfaced angular particles. They described the different erosion mechanisms based on the angularity of abrasives by the angle between the perpendicular to the surface and the leading edge of particle. It is found that cutting is favored when the rake angle is positive or small negative values. At large negative rake angles, ploughing rather than cutting occurs. Since spherical particles always have negative rake angles at impact, ploughing is the only possible deformation. Because most of the abrasives are both round and angular, the deformation can be either cutting or ploughing. Particle size also influences erosion of ductile material as much as its shape. Many investigators support the idea that particle size influences erosion rates for smaller 12 sizes。 however, the cutting action has three different types that depend on the shape and orientation of the erodent particles. For the erosion by oblique impact of spherical particles, the material is removed by a ploughing action, displacing materials to the front and side of the particle. Further impacts on the neighboring site cause removal of highly strained materials from the rim or terminal lip of the crater. For angular shaped particles, Hutchings (1992) proposed a similar mechanism to that by Finnie (1958) and Bitter (1963), although the cutting action is acknowledged to be two different types depending on the orientation of the erodent particle as is strikes the target surface, as well as whether the particle rolls forward or backward during contact. Regardless of the erosion mechanism, the most vulnerable parts of production systems tend to be ponents in which: 1) the flow direction changes suddenly, 2) high flow velocities occur caused by high volumetric flow rates and, 3) high flow velocities occur caused by flow restrictions. Components and pipework upstream of the primary separators carry multiphase mixtures of gas, liquid and particulates and are consequently more likely to suffer from solid particle erosion. Additionally, some geometries such as elbows, plug tees and other kind of bends may possess plex flow characteristics. For instance, in an elbow with sufficiently high Reynolds number flow, the boundary layer separation and a pair of counterrotating vortices that develop through the bend and extend into the exit pipe can be experienced. This behavior of counterrotating vortices can have an effect on both the magnitude and location of erosion damage depending on the size of the particles. Solid Particle Erosion Models\ In order to keep the piping system operating safely and minimize the loss caused by solid particle erosion, an erosion prediction method accounting for these main factors is always desired. With the ability of predicting solid particle erosion, one can estimate service life, predict erosion pattern and the locations in the geometry where severe erosion is likely to occur. Solid particle erosion equations invariably include factors relating to the nature of the wall material ( K ), the velocity of the particles ( V ), the mass of particles impacting a surface (Pm ? ) and the angle of impact ( θ ) and the hardness of the material impacted: The system factor ( K ) is empirically determined. The particle velocity exponent n is usually in the range of to 5, making it very important。時間的倉促及自身專業(yè)水平的不足，整篇論文肯定存在尚未發(fā)現(xiàn)的缺點和錯誤。感謝我們小組的各位同學(xué)，與他們的交流使我受益頗多。從論文的選題、文獻(xiàn)的采集、框架的設(shè)計、結(jié)構(gòu)的布局到最終的論文定稿，從內(nèi)容到格式，從標(biāo)題到標(biāo)點，她都費盡心血。老師的諄諄誘導(dǎo)、同學(xué)的出謀劃策及家長的支持鼓勵，是我堅持完成論文的動力源泉。在這四年的時間里，我在學(xué)習(xí)上和思想上都受益非淺。 Glenn H. IT fluent information literacy skill: A Delphi study of an essential course offering[D]. University of Phoenix致謝畢業(yè)論文暫告收尾，這也意味著我在太原理工大學(xué)現(xiàn)代科技學(xué)院的四年的學(xué)習(xí)生活既將結(jié)束。 Adam. Proton exchange membrane fuel cell modeling and simulation using Ansys Fluent[D]. Arizona State .[18] Sweeten。、出口70mm各橫截面壓強(qiáng)表1 、出口70mm各橫截面壓強(qiáng)出口70mm壓強(qiáng)圖位置（m)0壓強(qiáng)（Pa）418803899367008210442256.82422275.02912295.8 出口70mm各橫截面壓強(qiáng)、出口90mm各橫截面壓強(qiáng)表出口90mm各橫截面壓強(qiáng)出口90mm壓強(qiáng)圖位置（m)0壓強(qiáng)（Pa）6492828375695529368361951019.48 出口90mm各橫截面壓強(qiáng)小結(jié)：兩條壓強(qiáng)圖總體都是呈下降趨勢；，在出口處降到最低；出口70mm的減壓裝置比90mm的減壓裝置減壓效果更好表出口不同模型的減壓效果出口不同模型的減壓效果 　In（Pa）Out(Pa)壓強(qiáng)差(Pa)70mm90mm由表5可以得出出水口70mm的裝置比出水口90mm的減壓裝置減壓效果更好。點擊Compute。依次點擊Report—Surface Intergrals打開Surface Intergrals對話框， Surface Intergrals對話框在Report Type中選擇AreaWeighted Average；在Filed Variable中選擇Pressure（壓強(qiáng)），Total Pressure。取z=,z=,z=,z=,z=。壓強(qiáng)圖如下。取等值面Z=，點擊Displa—Contours,打開Contours對話框。依次創(chuàng)建Z=,Z=,Z=,Z=。 IsoSurface對話框取Z=。 顯示網(wǎng)格、創(chuàng)建等值面。點擊Display—Grid，彈出Grid Display 對話框。Data，讀取文件。、讀入之前保存的Case和Data文件。、FLUENT數(shù)據(jù)處理。經(jīng)過一段事件后，在迭代102次后收斂，（）所