针对集流管结构严重影响旋喷泵性能这一问题,本文以专用的旋喷泵开式试验台和5种安装不同结构集流管的模型泵为研究对象,分析了集流管结构对旋喷泵内、外特性影响。数值计算为避免各向同性涡粘假设,选择雷诺应力RSM linear pressure-str...针对集流管结构严重影响旋喷泵性能这一问题,本文以专用的旋喷泵开式试验台和5种安装不同结构集流管的模型泵为研究对象,分析了集流管结构对旋喷泵内、外特性影响。数值计算为避免各向同性涡粘假设,选择雷诺应力RSM linear pressure-strain模型,将数值计算结果与试验结果对比以验证其可信度。结果表明:试验泵集流管进口直径过小或者过大都会导致旋喷泵扬程与效率的下降。集流管外形对旋喷泵的扬程、效率影响明显,翼形集流管扬程、效率较高。旋喷泵尾流区相对半径r′<0.5与r′>1.0范围内受旋壳效应影响,高速层和低速层之间动量传递剧烈,不同结构集流管在同一位置坐标雷诺应力数值差异普遍在10-4量级。研究结果可为集流管结构设计及选型提供重要基础。展开更多
以旋喷泵为试验对象,完成了旋壳与叶轮同步变转速性能试验以及旋壳与叶轮非同步差速数值研究.为避免各向同性涡黏假设,数值计算选择雷诺应力RSM linear pressure-strain模型,将数值计算与试验结果对比以验证其可信度.结果表明:变转速试...以旋喷泵为试验对象,完成了旋壳与叶轮同步变转速性能试验以及旋壳与叶轮非同步差速数值研究.为避免各向同性涡黏假设,数值计算选择雷诺应力RSM linear pressure-strain模型,将数值计算与试验结果对比以验证其可信度.结果表明:变转速试验中该泵的流量与扬程符合相似定律,最优效率基本保持不变,各转速下最优效率的最大偏差为3.1%,趋于常数.差速试验中旋壳转速升高引起径向液体压力梯度增大,导致旋壳内任意位置半径r大于叶轮出口半径r2区域的液体压力增加,而旋壳内任意位置半径小于叶轮出口半径区域液体的压力降低.受叶轮与旋壳差速扰动影响,集流管进口和尾涡区域湍流动能数值普遍较高,该区域能量损失大,涡的大小、形态、涡心位置随旋壳转速不断变化,主要分布在叶轮出口与流动中心区.与额定工况相比,旋壳转速的升高能够提高旋喷泵的扬程,但由内壁面带动液体快速旋转增加液体能量的方式会导致泵效率下降.旋壳转速在一定范围内的降低有利于能源的高效利用,提高泵效率,该泵试验范围内最优旋壳与叶轮转速比为0.75,研究结果对今后旋喷泵差速运行有指导意义.展开更多
In recent years,single-atom catalysts(SACs)have attracted increasing attention in catalysis.However,their stability is considerably challenging.As a result,fine-tuning the interaction of metal single atoms(SA)with dif...In recent years,single-atom catalysts(SACs)have attracted increasing attention in catalysis.However,their stability is considerably challenging.As a result,fine-tuning the interaction of metal single atoms(SA)with different types of supports has emerged as an effective strategy for improving their thermal and chemical stabilities.Owing to its non-toxicity,cost-effectiveness,high abundance,and excellent stability,as well as presence of rich,tunable,and reliable anchor sites for metal SA,TiO_(2)has been extensively explored as a superior support for SACs.In this review,recent advances of TiO_(2)-supported SACs(M1/TiO_(2))are discussed,and synthetic strategies,structure elucidation,and catalytic applications are summarized.First,the recently developed synthetic strategies for M1/TiO_(2)arehighlighted and summarized,identifying the major challenges for the precise fabrication of M1/TiO_(2).Subsequently,key characterization techniques for the structure identification of M1/TiO_(2)are discussed.Next,catalytic applications of M1/TiO_(2)are highlighted,viz.photocatalysis,electrocatalysis,and thermocatalysis.In addition,the mechanism via geometric structures and electronic states of metal centers facilitate catalytic reactions is outlined.Finally,opportunities and challenges of M1/TiO_(2)in catalysis are discussed,which may inspire the future development of M1/TiO_(2)for multifunctional catalytic applications.展开更多
文摘为研究旋壳转速对腔内液体流动特性的影响,以试验旋喷泵为研究对象,在高度验证叶轮与旋壳同步旋转试验与模拟结果准确性的基础上,对叶轮转速相同、旋壳转速不同的5个模型采用RNG k-ε湍流模型进行数值计算,分析腔内液体流动特性的变化情况,研究泵的性能.结果表明:旋壳转速增大,液体圆周速度和旋转系数均增大,圆周速度曲线沿径向逐渐形成同心圆,腔内液体做非刚性旋转.腔内液体径向压力梯度增大,压力低于624 kPa时,旋壳转速越高,压力越小;压力高于624 kPa时,旋壳转速越高,压力越大.集流管迎流区涡分布在进口附近,尾迹区涡集中在扩散段结尾处,整体呈增大趋势.旋壳转速增大,泵的扬程升高,但效率降低,通过改变集流管进口直径发现集流管并非效率降低的主要原因,而是由圆盘摩擦损失的增大导致的,圆盘摩擦损失随旋壳转速增加呈3次幂函数式增大,文中最优进口直径为13 mm.
文摘针对集流管结构严重影响旋喷泵性能这一问题,本文以专用的旋喷泵开式试验台和5种安装不同结构集流管的模型泵为研究对象,分析了集流管结构对旋喷泵内、外特性影响。数值计算为避免各向同性涡粘假设,选择雷诺应力RSM linear pressure-strain模型,将数值计算结果与试验结果对比以验证其可信度。结果表明:试验泵集流管进口直径过小或者过大都会导致旋喷泵扬程与效率的下降。集流管外形对旋喷泵的扬程、效率影响明显,翼形集流管扬程、效率较高。旋喷泵尾流区相对半径r′<0.5与r′>1.0范围内受旋壳效应影响,高速层和低速层之间动量传递剧烈,不同结构集流管在同一位置坐标雷诺应力数值差异普遍在10-4量级。研究结果可为集流管结构设计及选型提供重要基础。
文摘以旋喷泵为试验对象,完成了旋壳与叶轮同步变转速性能试验以及旋壳与叶轮非同步差速数值研究.为避免各向同性涡黏假设,数值计算选择雷诺应力RSM linear pressure-strain模型,将数值计算与试验结果对比以验证其可信度.结果表明:变转速试验中该泵的流量与扬程符合相似定律,最优效率基本保持不变,各转速下最优效率的最大偏差为3.1%,趋于常数.差速试验中旋壳转速升高引起径向液体压力梯度增大,导致旋壳内任意位置半径r大于叶轮出口半径r2区域的液体压力增加,而旋壳内任意位置半径小于叶轮出口半径区域液体的压力降低.受叶轮与旋壳差速扰动影响,集流管进口和尾涡区域湍流动能数值普遍较高,该区域能量损失大,涡的大小、形态、涡心位置随旋壳转速不断变化,主要分布在叶轮出口与流动中心区.与额定工况相比,旋壳转速的升高能够提高旋喷泵的扬程,但由内壁面带动液体快速旋转增加液体能量的方式会导致泵效率下降.旋壳转速在一定范围内的降低有利于能源的高效利用,提高泵效率,该泵试验范围内最优旋壳与叶轮转速比为0.75,研究结果对今后旋喷泵差速运行有指导意义.
基金National Natural Science Foundation of China(Nos.21805191,21972094,22102102)China Postdoctoral Science Foundation(No.2021T140472)+1 种基金Guangdong Basic and Applied Basic Research Foundation,China(No.2020A1515010982)Shenzhen Science and Technology Program,China(Nos.20200812122947002,20200812160737002,RCJC20200714114434086,827-000421).
文摘In recent years,single-atom catalysts(SACs)have attracted increasing attention in catalysis.However,their stability is considerably challenging.As a result,fine-tuning the interaction of metal single atoms(SA)with different types of supports has emerged as an effective strategy for improving their thermal and chemical stabilities.Owing to its non-toxicity,cost-effectiveness,high abundance,and excellent stability,as well as presence of rich,tunable,and reliable anchor sites for metal SA,TiO_(2)has been extensively explored as a superior support for SACs.In this review,recent advances of TiO_(2)-supported SACs(M1/TiO_(2))are discussed,and synthetic strategies,structure elucidation,and catalytic applications are summarized.First,the recently developed synthetic strategies for M1/TiO_(2)arehighlighted and summarized,identifying the major challenges for the precise fabrication of M1/TiO_(2).Subsequently,key characterization techniques for the structure identification of M1/TiO_(2)are discussed.Next,catalytic applications of M1/TiO_(2)are highlighted,viz.photocatalysis,electrocatalysis,and thermocatalysis.In addition,the mechanism via geometric structures and electronic states of metal centers facilitate catalytic reactions is outlined.Finally,opportunities and challenges of M1/TiO_(2)in catalysis are discussed,which may inspire the future development of M1/TiO_(2)for multifunctional catalytic applications.
