The benefits of planar circular mouths on suction feeding performance

Suction feeding is the most common form of prey capture across aquatic feeding vertebrates and many adaptations that enhance efficiency and performance are expected. Many suction feeders have mechanisms that allow the mouth to form a planar and near-circular opening that is believed to have beneficial hydrodynamic effects. We explore the effects of the flattened and circular mouth opening through computational fluid dynamics simulations that allow comparisons with other mouth profiles. Compared to mouths with lateral notches, we find that the planar mouth opening results in higher flow rates into the mouth and a region of highest flow that is positioned at the centre of the mouth aperture. Planar mouths provide not only for better total fluid flow rates through the mouth but also through the centre of the mouth near where suction feeders position their prey. Circular mouths are shown to provide the quickest capture times for spherical and elliptical prey because they expose the prey item to a large region of high flow. Planar and circular mouths result in higher flow velocities with peak flow located at the centre of the mouth opening and they maximize the capacity of the suction feeders to exert hydrodynamic forces on the prey.     

Exploratory Study on Cyclones of Modified Designs

This paper introduces a new design of cyclone, named triple cyclone, created by adding two more cylinders to the conventional cyclone. The performance of the triple cyclone was evaluated systematically together with the previously reported double cyclone. The tests showed that the collection efficiencies of double and triple cyclones were lower than those of the conventional cyclone with the same body diameter and identical gas inlet and outlet size. Of the three designs, the collection efficiency of the triple cyclone was the lowest. Accordingly, the highest pressure drop was observed for the conventional cyclone, and the pressure drop for the triple cyclone was the lowest. These results are probably attributed to the relatively weak vortices formed within triple and double cyclones.     

低压投煤技术在壳牌煤气化装置中的应用

壳牌煤气化装置低压投煤开车技术要求开工烧嘴在较低热负荷情况下的运行时间尽可能短,且气化炉压力在0.1～0.5 MPa（原设计为0.8～1.0 MPa）时就投用煤烧嘴,并通过煤烧嘴的运行来为气化炉升温升压,直至装置满负荷运行。分析了壳牌煤气化装置采用高压投煤开车存在的主要问题及其原因;对比了高压投煤和低压投煤的运行情况;...     

回转窑下料管冷却循环系统的技术改进

针对回转窑下料管经常发生开裂和烧损的现象，本文分析了下料管开裂和烧损的原因，提出将原使用的自循环工业水改为软化水和改进冷却循环系统的进出水管。改进后延长了下料管的使用寿命，同时达到了有效利用余热的效果。     

基于非接触给电的高主轴转速微细电火花加工特性研究

在实现非接触给电的微细电火花加工的基础上,分别研究了圆柱电极和削边电极的主轴转速对材料去除率及电极损耗的影响。结果表明:无论是圆柱电极还是削边电极,随着主轴转速的提高,材料去除率增加,电极损耗率降低;且在削边电极的情况下,主轴转速的提高对于材料去除率和电极损耗率的改善更明显。     

多工位冲压生产线自动送料机械手控制系统设计

为了提高大型多工位压力机生产线的自动化程度,提出了一种基于PLC和运动控制器共同控制的三次元送料机械手控制系统设计方案。对送料机械手的整体结构、工作流程、伺服系统组成进行了研究和分析,阐述了控制系统的硬件结构设计,详细介绍了PLC以及运动控制器的软件功能设计,并采用触摸屏设计了友好的人机界面。在轨迹控制方面,采用电子凸轮实现机械手在X、Y、Z方向及8个伺服轴的联动。根据机械手的实际运行状况,通过反复实践整定伺服增益参数,得到了理想的响应特性。实验结果表明,该机械手操作方便、运行稳定,当移送负载为120 kg时,机械手的工作速度可达25次·min~(-1)。     

低油价形势下改善稠油热采开发效果对策研究

针对胜利油田边底水能量强、原油黏度高、油层厚度薄、储层物性差、强水敏等油藏特征,以及稠油油藏热采开发成本高的特点,分析了当前低油价形势下稠油热采无效直井的治理对策。通过研究,提出了强边水油藏一线井提液二线井调剖、优化注汽参数、组合吞吐、分层注汽和氮气补充地层能量等技术措施,有针对性地解决了高含水井、无效益井的问题。现场应用表明,该系列技术对策有效提高了热采直井的开发效果,取得了良好的经济效益。     

异种钛合金协同送丝等离子增材制造试验

采用双丝协同等离子增材系统实现了TC4-TA2异种钛合金的增材成形,期望制备的增材构件具有良好的沉积形貌及优异的力学性能. 采用了体视显微镜、扫描电镜、EDS、XRD、拉伸及硬度等测试方法分析其组织及性能. 结果表明,增材构件中存在两种微观组织形态,即分布在沉积层交界处的α相集束组织和分布在沉积层中心的α + β相片层组织. 构件在竖直和水平方向上的抗拉强度分别为998和1 037 MPa,断后伸长率为9.2%和5.7%,断裂呈现为脆性解理断裂. 试验结果证明,等离子增材制造技术能够实现异种钛合金协同增材成形.