基于中粗砂土质输送工况的泥泵轴系疲劳寿命研究

绞吸挖泥船泥泵泵轴的断裂事故时有发生,直接影响疏浚工程的进度和效益。以厦门机场大小嶝造地工程为背景,3500 m~3/h绞吸挖泥船的泥泵轴系为研究对象,建立了泥泵在流量11000 m~3/h、泥砂粒径0.7 mm、混合物体积浓度20%工况下的疲劳寿命预测模型。通过对泥泵运转过程中的多相流场数值分析和对泥泵轴系瞬态动应力响应分析,提取泵轴关键节点处的应力时间历程数据,结合S-N曲线法和线性累积损伤原理,分析泵轴时域疲劳特性,预测相应工况下的泥泵轴系疲劳寿命。以此为基础,为进一步优化施工工艺和提升泵轴运转寿命提供建议。

Nonlinear multi body dynamic modeling and vibration analysis of a double drum coal shearer

The double drum coal shearer is widely applied for the underground coal exploration in the mining industry.The vibration and noise control are significant factors for the stability design of the double drum coal shearer.In this paper,the vibration properties of a double drum coal shearer are firstly investigated.The horizontal,transverse and torsional vibrations of the motor body and the angle displacements of the rockers are taken into account.The walking units and the hydraulic units are modeled by the stiffness-damping systems.The nonlinear equation of motion of the double drum coal shearer is established by applying the Lagrange’s equation.The nonlinear vibration response of the system is calculated by using the Runge Kutta numerical method.The effects of the shearing loads,the equivalent damping and stiffness of the walking units,the inclination angels of the rockers and the equivalent damping and stiffness of the hydraulic units on the vibration properties of the system are discussed.

STUDY ON BLASTING DESCALING IN THE SOOT-DELIVERY PIPE

An experiment model, scaled 1: 1, designed for studying a blasting method to clear away soot in a soot-delivery pipe in coal-burning power plant is described. By mixing RDX and Nitramon on a particular scale and sticking the explosive cartridge on the outwall surface of the pipe, the experimental result makes clear that the controlled blasting method can get rid of the soot effectively. Under the action of the blasting compression wave and reflectance tension wave,the soot is destroyed effectively in the region of - 60° ~60° around the bIasting site, that creates a condition for the second blasting in the surplus soot.

Doping Copper Ions in a Metal-Organic Framework(UiO-66-NH2):Location Effect Examined by Ultrafast Spectroscopy

We constructed two types of copper-doped metal-organic framework(MOF),i.e.,Cu@UiO-66-NH2 and Cu-UiO-66-NH2.In the former,Cu2+ions are impregnated in the pore space of the amine-functionalized,Zr-based UiO-66-NH2;while in the latter,Cu^2+ions are incorporated to form a bimetal-center MOF,with Zr^4+being partially replaced by Cu2+in the Zr-O oxo-clusters.Ultrafast spectroscopy revealed that the photoinduced relaxation kinetics associated with the ligand-to-cluster charge-transfer state is promoted for both Cudoped MOFs relative to undoped one,but in a sequence of Cu-UiO-66-NH2>Cu@UiO-66-NH2>UiO-66-NH2.Such a sequence turned to be in line with the trend observed in the visible-light photocatalytic hydrogen evolution activity tests on the three MOFs.These findings highlighted the subtle effect of copper-doping location in this Zr-based MOF system,further suggesting that rational engineering of the specific metal-doping location in alike MOF systems to promote the photoinduced charge separation and hence suppress the detrimental charge recombination therein is beneficial for achieving improved performances in MOF-based photocatalysis.

高比转速混流式水轮机叶道涡工况下转轮的动力特性分析

为了探讨叶道涡对混流式转轮叶片的作用机理,以某高比转速混流式水轮机为研究对象,选取出现严重叶道涡的小流量工况点开展转轮的瞬态动应力数值模拟。首先基于Navier-Stokes方程和RNG k-ε湍流模型进行了全流道定常和非定常流动计算,得出了转轮内部叶道涡的形态及分布,与实际观测现象非常吻合;然后采用有限元方法对转轮进行了模态分析,获得了转轮在水中的固有频率及振型;最后采用流固耦合方法对转轮进行瞬态动力学分析。研究结果表明:叶片危险部位的动应力的频率为转轮频率的倍频,分布于转轮叶片出口靠近上冠处的局部叶道涡对转轮的作用强度最大,导致叶片出口与上冠连接处的最大动应力值高于一般水轮机转轮的许用应力值,引起转轮该位置发生破坏甚至产生裂纹。