Journal of Zhejiang University-SCIENCE A最新文献_第4页

Numerical modeling and experimental investigation of a two-phase sink vortex and its fluid-solid vibration characteristics 两相沉降涡及其流固振动特性的数值建模和实验研究

Journal of Zhejiang University-SCIENCE A Pub Date : 2024-01-01 DOI: 10.1631/jzus.A2200014

Zichao Yin, Y. Ni, Lin Li, Tong Wang, Jiafeng Wu, Zhe Li, Da-peng Tan

{"title":"Numerical modeling and experimental investigation of a two-phase sink vortex and its fluid-solid vibration characteristics","authors":"Zichao Yin, Y. Ni, Lin Li, Tong Wang, Jiafeng Wu, Zhe Li, Da-peng Tan","doi":"10.1631/jzus.A2200014","DOIUrl":"https://doi.org/10.1631/jzus.A2200014","url":null,"abstract":"A sink vortex is a common physical phenomenon in continuous casting, chemical extraction, water conservancy, and other industrial processes, and often causes damage and loss in production. Therefore, the real-time monitoring of the sink vortex state is important for improving industrial production efficiency. However, its suction-extraction phenomenon and shock vibration characteristics in the course of its formation are complex mechanical dynamic factors for flow field state monitoring. To address this issue, we set up a multi-physics model using the level set method (LSM) for a free sink vortex to study the two-phase interaction mechanism. Then, a fluid–solid coupling dynamic model was deduced to investigate the shock vibration characteristics and reveal the transition mechanism of the critical flow state. The numerical results show that the coupling energy shock induces a pressure oscillation phenomenon, which appears to be a transient enhancement of vibration at the vortex penetration state. The central part of the transient enhancement signal is a high-frequency signal. Based on the dynamic coupling model, an experimental observation platform was established to verify the accuracy of the numerical results. The water-model experiment results were accordant with the numerical results. The above results provide a reference for fluid state recognition and active vortex control for industrial monitoring systems, such as those in aerospace pipe transport, hydropower generation, and microfluidic devices. 目的汇流旋涡的实时监测可有效促进冶金精炼、燃料系统、水力发电等工业场景的提质增效. 本文旨在建立两相旋涡流固耦合模型, 获取壁面冲击振动信号和提取旋涡贯穿特征, 以期为工业防涡和抑涡提供理论参考与技术支持. 创新点 1. 建立了涡流力学模型, 得到了临界贯入状态的规律; 2. 建立了流固耦合模型, 得到了涡激振动信号; 3. 提出了一种基于四方程的振动响应求解方法. 方法 1. 采用水平集方法, 建立自由汇流旋涡模型来研究气液两相作用机理; 2. 建立流固耦合动力学模型, 研究冲击振动特性, 并揭示临界流动状态的转变机理; 3. 搭建实验观测平台, 验证数值计算结果的准确性. 结论 1. 涡流耦合能量引起的压力振荡是流固冲击振动产生的根本原因; 2. 旋涡达到临界穿透状态时, 两相耦合引起的压力振荡导致各频率信号显著增强, 且高频波段尤为明显; 3. 根据流体动力学相似理论搭建的实验平台可基于冲击振动特性实现对汇流旋涡的实时监测.","PeriodicalId":508023,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139540739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Effect of nitrile butadiene rubber hardness on the sealing characteristics of hydraulic O-ring rod seals 丁腈橡胶硬度对液压 O 型圈杆密封件密封特性的影响

Journal of Zhejiang University-SCIENCE A Pub Date : 2024-01-01 DOI: 10.1631/jzus.A2200612

Xiaoxuan Li, Bingqing Wang, X.-L. Peng, Yuntang Li, Xiaolu Li, Yuan Chen, Jie Jin

{"title":"Effect of nitrile butadiene rubber hardness on the sealing characteristics of hydraulic O-ring rod seals","authors":"Xiaoxuan Li, Bingqing Wang, X.-L. Peng, Yuntang Li, Xiaolu Li, Yuan Chen, Jie Jin","doi":"10.1631/jzus.A2200612","DOIUrl":"https://doi.org/10.1631/jzus.A2200612","url":null,"abstract":"目的研究丁腈橡胶硬度对O形液压杆封静/动态密封性能的影响, 为其工程中橡胶硬度的选型提供理论参考. 创新点 1. 基于混合弹流润滑模型, 分析了丁腈橡胶硬度对O形液压杆封静/动态密封性能的影响; 2. 以低泄漏、低摩擦为目标, 获得了静/动态应用下丁腈橡胶O形液压杆封的橡胶硬度优选范围. 方法 1. 通过数值分析静接触压力、 von Mises应力、最小液膜厚度、泄漏率和摩擦力, 揭示丁腈橡胶硬度对O形液压杆封静/动态密封性能的影响机理; 2. 以最大静接触压力和最大von Mises应力作为静密封性能评价指标, 以及以净泄漏量和摩擦功耗作为动密封性能的评价指标, 确定丁腈橡胶O形液压杆封的最佳橡胶硬度值. 结论 1. 随着橡胶硬度的增加, 丁腈橡胶O形液压杆封的抗变形能力增强, 静接触压力增大, 最小液膜厚度减小, 泄漏量减小, 摩擦力增大; 2. 低硬度密封易产生挤出效应和应力集中现象, 因此更适合在高速或低密封性要求的场合使用; 3. 高硬度密封具有更优的静/动态密封性能, 所以特别适用于高压工况场合, 但由于其摩擦力较大, 因此在满足泄漏要求的前提下应尽量选择相对较低的橡胶硬度以减小摩擦. The nitrile butadiene rubber (NBR) hardness effect on the sealing characteristics of hydraulic O-ring rod seals is analyzed based on a mixed lubrication elastohydrodynamic model. Parameterized studies are conducted to reveal the mechanism of the influence of rubber hardness on the static and dynamic behavior of seals. The optimized selections of rubber hardness are then investigated under different conditions. Results show that the low hardness seal is prone to stress concentration due to the extrusion effect under high pressure conditions; it is also more prone to leaking. A high hardness seal can better prevent leakage by reducing film thickness but it will cause large frictional power loss and increase the probability of wear failure. The choice of low hardness is recommended to reduce friction with the premise that leakage requirements are met.","PeriodicalId":508023,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139537110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

邻近盾构施工对既有隧道沉降的影响:现场监测与智能预测邻近盾构施工对既有隧道沉降的影响:现场监测与智能预测

Journal of Zhejiang University-SCIENCE A Pub Date : 2023-11-22 DOI: 10.1631/jzus.a2200573

Longmin Ran, Yang Ding, Qizhi Chen, Baoping Zou, Xiaowei Ye

引用次数: 0

Prediction of maximum upward displacement of shield tunnel linings during construction using particle swarm optimization-random forest algorithm 使用粒子群优化-随机森林算法预测施工期间盾构隧道衬砌的最大向上位移

Journal of Zhejiang University-SCIENCE A Pub Date : 2023-11-21 DOI: 10.1631/jzus.a2300011

Xiaowei Ye, Xiaolong Zhang, Yanbo Chen, Yujun Wei, Yang Ding

引用次数: 0

Core-drilling kinematic modeling and analysis of Jiaolong submersible manipulator 蛟龙号潜水机械手的岩心钻探运动学建模与分析

Journal of Zhejiang University-SCIENCE A Pub Date : 2023-11-01 DOI: 10.1631/jzus.A2200484

Xu Yang, Xin Liu, Shizhen Li, Yugang Ren, Limin Zhu

引用次数: 0

Effect of carbon dioxide concentration on the combustion characteristics of boron agglomerates in oxygen-containing atmospheres 二氧化碳浓度对含氧大气中硼结块燃烧特性的影响

Journal of Zhejiang University-SCIENCE A Pub Date : 2023-11-01 DOI: 10.1631/jzus.A2200468

Lian Duan, Zhixun Xia, Yunchao Feng, Binbin Chen, Jiarui Zhang, Likun Ma

{"title":"Effect of carbon dioxide concentration on the combustion characteristics of boron agglomerates in oxygen-containing atmospheres","authors":"Lian Duan, Zhixun Xia, Yunchao Feng, Binbin Chen, Jiarui Zhang, Likun Ma","doi":"10.1631/jzus.A2200468","DOIUrl":"https://doi.org/10.1631/jzus.A2200468","url":null,"abstract":"In ramjet combustion chambers, carbon dioxide (CO2) produced by the combustion of carbonaceous fuel enters the chamber together with boron agglomerates. In order to investigate the effect of CO2 concentration present in an oxygen-containing atmosphere on the combustion characteristics and oxidation mechanisms of boron agglomerates, we used a laser ignition system, an X-ray diffractometer (XRD), and a thermogravimetric-differential scanning calorimetry (TG-DSC) combined thermal analysis system. Single-particle boron was tested in the laser-ignition experiments as the control group. The ignition experiment results showed that with a fixed O2 concentration of 20%, when the particle temperature reaches the melting point of boron, increasing CO2 content causes the combustion process of boron agglomerates to transition from single-particle molten droplet combustion to porous-particle combustion. Furthermore, XRD analysis results indicated that the condensed-phase combustion products (CCPs) of boron particles in a mixed atmosphere of O2 and CO2 contained B4C, which is responsible for the porous structure of the particles. At temperatures below 1200 °C, the addition of CO2 has no obvious promotion effect on boron exothermic reaction. However, in the laser-ignition experiment, when the oxygen concentration was fixed at 20% while the CO2 concentration increased from 0% to 80%, the maximum temperature of boron agglomerates rose from 2434 to 2573 K, the self-sustaining combustion time of single-particle boron decreased from 396 to 169 ms, and the self-sustaining combustion time of boron agglomerates decreased from 198 to 40 ms. This study conclusively showed that adding CO2 to an oxygen-containing atmosphere facilitates boron reaction and consumption pathways, which is beneficial to promoting exothermic reaction of boron agglomerates at relatively high temperatures.","PeriodicalId":508023,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139301247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Short-term tunnel-settlement prediction based on Bayesian wavelet: a probability analysis method 基于贝叶斯小波的短期隧道沉降预测：一种概率分析方法

Journal of Zhejiang University-SCIENCE A Pub Date : 2023-11-01 DOI: 10.1631/jzus.A2200599

Yang Ding, Xiaowei Ye, Zhi Ding, Gang Wei, Yunliang Cui, Zhen Han, Tao Jin

{"title":"Short-term tunnel-settlement prediction based on Bayesian wavelet: a probability analysis method","authors":"Yang Ding, Xiaowei Ye, Zhi Ding, Gang Wei, Yunliang Cui, Zhen Han, Tao Jin","doi":"10.1631/jzus.A2200599","DOIUrl":"https://doi.org/10.1631/jzus.A2200599","url":null,"abstract":"As urbanization accelerates, the metro has become an important means of transportation. Considering the safety problems caused by metro construction, ground settlement needs to be monitored and predicted regularly, especially when a new metro line crosses an existing one. In this paper, we propose a settlement-probability prediction model with a Bayesian emulator (BE) based on the Gaussian prior (GP), that is, a GPBE. In addition, considering the distortion characteristics of monitoring data, the data is denoised using wavelet decomposition (WD), so the final prediction model is WD-GPBE. In particular, the effects of different prediction ratios and moving windows on prediction performance are explored, and the optimal number of moving windows is determined. In addition, the predicted value for GPBE based on the original data is compared with the predicted value for WD-GPBE based on the denoised data. One year of settlement-monitoring data collected by a structural health monitoring (SHM) system installed on the Nanjing Metro is used to demonstrate the effectiveness of WD-GPBE and GPBE for predicting settlement.","PeriodicalId":508023,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139299291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0