Numerical Investigation of a New Method for Reducing Bends Erosion from Particles Impacts

The present paper intends to introduce a new method for reducing bends erosion from particles impacts: the ribbed bend erosion protection method. Ribs are evenly fixed in the range of 20°-80° on the inner-wall of inside 90?bend and the bend (including ribs) is made of medium carbon steel. Three-dimensional numerical work is performed and the result shows satisfactory agreement with the experimental measurement. Numerical simulation studies the characteristics of axial gas flow along the bend and secondary flow at cross section. Detailed analyses involving the impact velocity and incidence angle of particle-metal (either particle-rib or particle-duct) impact unveil the mechanism of the anti-erosion effect. As a result, predications achieve that the average erosion rate of the ribbed bends is only a third of the bare bend under test conditions and rectangle ribs possess higher anti-erosion effect than square ribs, while the wear distribution pattern remains unchanged after adding ribs onto the bend. All     

用高电压脉冲电场促进牛骨可溶性钙快速溶出

以柠檬酸和苹果酸的复合物作为混合酸,采用高电压脉冲电场(PEF)技术对牛骨中钙盐的溶出进行了研究。结果表明:该技术与传统方法相比,具有溶钙量高,速度快的特点。建立了场强、脉冲数、加酸量对溶出可溶性钙影响的数学模型,确定了最佳工艺参数:电场强度23 kV/cm,脉冲数12,混合酸量3.881 g,该条件下溶出的钙离子含量高达12.90 mg/mL。     

仿生形态表面气固冲蚀磨损性能

根据试验优化设计理论,利用L27(313)三水平正交表设计试验,对具有凹坑形、凹槽形、圆环形仿生形态表面的试件进行冲蚀磨损试验研究,运用极差分析处理试验数据,得到三种表面形态试件的冲蚀率与各试验因素之间的关系。结果表明:试验因素对冲蚀率的影响程度由大到小依次为砂子目数、转速、喷砂量、形态;冲蚀率随着目数、转速的增大而增大;所有一级交互作用中,形态和喷砂量之间的交互作用对冲蚀率的影响最大,目数和转速之间的交互作用对冲蚀率的影响最小。     

淤地坝对黄土高原坡沟系统重力侵蚀调控研究

坡沟系统是黄土高原的特有问题,目前有关坡沟系统重力侵蚀的研究相对较少,针对这种情况,采用了国际上最为通用的大型有限元分析软件ANSYS,结合强度折减理论,对碾庄沟流域坡沟系统概化模型在不同典型淤积厚度下的边坡稳定进行了计算,分析了随着流域淤地坝系淤积至不同的典型淤积厚度时坡沟系统的第一主应力和Y方向位移的变化云图,建立了稳定系数和淤积厚度、滑塌体积与淤积厚度的相关方程,揭示了随着淤积厚度的增加,坡沟系统稳定性逐渐增大,重力侵蚀量或侵蚀潜力显著减少的规律.     

黑化集团75T/h循环流化床锅炉改造技术浅析

国产循环流化床锅炉已有十多年投运时间.该炉型有对燃料适应性广,燃烧效率高,炉内传热能力强,N0x和S0x排放量低等优点.但在实际运行中同时也暴露了一些问题.本文分析了黑化集团热电厂7 5t/h循环流化床锅炉的中心筒变形、风帽寿命短、沸上段水冷壁磨损的原因,提出了改进措施.     

Particle erosion of infrared materials

Erosion test of some infrared (IR) optical crystals (Ge,ZnS,MgF2,and quartz) was conducted with a number of different erodents (glass bead,and angular SiC,SiO2,Al2O3 by a homemade gas-blasting erosion tester.The influence of impact angle,impact velocity,erodent,and erosion time on the erosion rate and the effect of erosion on their IR transmittance were studied.The damaged surface morphology was characterized by scanning electron microscopy,and the erosion mechanism was explored.All of the materials show the maximum in wear versus impact angle at 90°,confirming their brittle failure behavior.It is found that the erosion rate is dependent on the erodent velocity by a power law,and it is highly correlated to the hardness of the erodent.The erosion rate-time curves do not show an incubation state,but an accelerated erosion period followed a maximum erosion (steady state).The decrease of IR transmittance is direct proportion to the erosion rate.Although the material loss occurs primarily by brittle process,ductile behavior is clearly an important feature,especially for MgF2 and ZnS.     

改进补偿模糊神经网络在坡面产沙模拟预报中的应用

土壤侵蚀产沙是一个极其复杂的物理过程,其物理机理十分复杂,往往难以用数学方式来描述.根据土壤侵蚀过程内在特点,采用一种改进的补偿模糊神经网络(CFNN)方法,对坡面侵蚀产沙过程进行了预测研究.利用四川某水土保持实验站观测数据,通过MATLAB语言编制程序进行了仿真试验, 全局误差为0.0517,预测值与实测值吻合良好,误差小于10%.结果表明,该方法预报精度较好,为坡面产沙模拟模型的建立提供了重要的参考方法.     

流域侵蚀产沙系统的复杂性

在介绍了复杂性科学的基础上,从其基本原理和观点出发,对流域侵蚀产沙系统的复杂性进行了深入分析,指出开放性和动态性、非平衡性和时空变异性、多尺度性、过程不可逆及多重耦合和性和非线性动力演化是流域侵蚀产沙系统复杂性的主要表现特征,以此为线索对复杂性科学的研究方法在流域侵蚀产沙过程模拟中的应用进行了较为系统地归纳,并对流域侵蚀产沙模型未来的研究趋势进行了展望.     

A new procedure to estimate the rainfall erosivity factor based on Tropical Rainfall Measuring Mission(TRMM) data

Soil erosion by water is the most important land degradation problem worldwide.In this paper a new procedure was developed to estimate the rainfall-runoff erosivity factor(R)based on Tropical Rainfall Measuring Mission(TRMM)satellite-estimated precipitation data,which consists of 3-h rainfall intensity data.In this method,R was calculated as the product of the maximum 180-min rainfall intensity and the rainfall energy.This procedure was applied to the Daling River basin in Liaoning Province,China,R in terms...     

高速公路建设项目水土流失影响分析评价

以大庆至肇源段高速公路工程等为例,针对高速公路建设的特点,采用水土流失影响指数的方法,选取水土流失影响时间、扰动强度、影响范围、可恢复程度、预测水土流失量等指标,定量分析工程建设对水土流失的综合影响程度。其计算结果与实际基本一致,可为政府部门、设计与施工单位提供高速公路建设的科学依据。