Experimental and numerical study of the performance and cavitation flow of centrifugal pump with jetting device

BaoLing Cui,Kaicheng Zhu,Yuliang Zhang,Peifeng Lin 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.10

Cavitation is a problem that must be considered when designing and operating a pump. This study proposes an active method using a jetting device to improve its cavitation performance. The influence of jetting flow rate on the external characteristics and cavitation performance of a centrifugal pump is analyzed through numerical simulation and experiment. Results show that the jetting fluid can improve the cavitation performance of a pump and the effect is most evident in the 6 % jetting flow rate. The distribution of entropy generation at the inlet pipe before the impeller shows that jetting flow can increase hydraulic loss in the pipe, thereby diminishing the performance of the centrifugal pump. An analysis of the transient cavitation flow in the centrifugal impeller under 6 % jetting flow rate reveals that the generation, development, and rupture of bubbles deteriorate the flow structure in the passage, thereby resulting in unstable flows and forces.

Influence of the jetting fluid on the internal flow in a centrifugal pump with jetting device

BaoLing Cui,Qianqian Yang,Kaicheng Zhu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3

Jetting the high pressure fluid from the outlet to the inlet is one of the methods to improve the cavitation characteristics. The influences of different jetting flow rates on the external characteristics and internal flow were investigated in the centrifugal pump with jetting device. The experiments were carried out to verify the performance calculated from the numerical simulation. The internal flow was analyzed under the design condition with 0-10 % jetting flow rate. The results indicate the jetting fluid makes the distributions of velocity more uneven in the jetting device. As the jetting flow increases, the entropy generation rate in the jetting device and inlet pipeline shows an incrementally increasing trend, indicating that the hydraulic loss is gradually increasing. At the same time, the pressure at the inlet of the impeller increases, and the turbulent kinetic energy decreases at the centrifugal pump impeller. This research is of great significance to effectively improve operational stability of the centrifugal pump.

Like a Playwright : Jerry’s Planning and Staging His Own Death in Edward Albee’s The Zoo Story

Zhang Baoling 새한영어영문학회 2019 새한영어영문학회 학술발표회 논문집 Vol.2019 No.10

Effects of the number of inducer blades on the anti-cavitation characteristics and external performance of a centrifugal pump

XiaoMei Guo,ZuChao Zhu,BaoLing Cui,GaoPing Shi 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.7

Installing an inducer upstream of the main impeller is an effective approach for improving the anti-cavitation performance of a highspeed centrifugal pump. For a high-speed centrifugal pump with an inducer, the number of inducer blades can affect its internal flow and external performance. We studied the manner in which the number of inducer blades can affect the anti-cavitation characteristics and external performance of a centrifugal pump. We first use the Rayleigh-Plesset equation and the mixture model to simulate the vaporliquid flow in a centrifugal pump with an inducer, and then predict its external performance. Finally, we tested the external performance of a centrifugal pump with 2-, 3- and 4-bladed inducers respectively. The results show that the simulations of external performance in a centrifugal pump are in accordance with our experiments. Based on this, we obtained vapor volume fraction distributions for the inducer, the impeller, and in the corresponding whole flow parts. We discovered that the vapor volume fraction of a centrifugal pump with a 3-bladed inducer is less than that of a centrifugal pump with 2- or 4-bladed inducers, which means that a centrifugal pump with a 3-bladed inducer has a better external and anti-cavitation performance.

STAT2 Knockout Syrian Hamsters Support Enhanced Replication and Pathogenicity of Human Adenovirus, Revealing an Important Role of Type I Interferon Response in Viral Control

Toth, Karoly,Lee, Sang R.,Ying, Baoling,Spencer, Jacqueline F.,Tollefson, Ann E.,Sagartz, John E.,Kong, Il-Keun,Wang, Zhongde,Wold, William S. M. Public Library of Science 2015 PLoS pathogens Vol.11 No.8

<▼1><P>Human adenoviruses have been studied extensively in cell culture and have been a model for studies in molecular, cellular, and medical biology. However, much less is known about adenovirus replication and pathogenesis <I>in vivo</I> in a permissive host because of the lack of an adequate animal model. Presently, the most frequently used permissive immunocompetent animal model for human adenovirus infection is the Syrian hamster. Species C human adenoviruses replicate in these animals and cause pathology that is similar to that seen with humans. Here, we report findings with a new Syrian hamster strain in which the STAT2 gene was functionally knocked out by site-specific gene targeting. Adenovirus-infected STAT2 knockout hamsters demonstrated an accentuated pathology compared to the wild-type control animals, and the virus load in the organs of STAT2 knockout animals was 100- to 1000-fold higher than that in wild-type hamsters. Notably, the adaptive immune response to adenovirus is not adversely affected in STAT2 knockout hamsters, and surviving hamsters cleared the infection by 7 to 10 days post challenge. We show that the Type I interferon pathway is disrupted in these hamsters, revealing the critical role of interferon-stimulated genes in controlling adenovirus infection. This is the first study to report findings with a genetically modified Syrian hamster infected with a virus. Further, this is the first study to show that the Type I interferon pathway plays a role in inhibiting human adenovirus replication in a permissive animal model. Besides providing an insight into adenovirus infection in humans, our results are also interesting from the perspective of the animal model: STAT2 knockout Syrian hamster may also be an important animal model for studying other viral infections, including Ebola-, hanta-, and dengue viruses, where Type I interferon-mediated innate immunity prevents wild type hamsters from being effectively infected to be used as animal models.</P></▼1><▼2><P><B>Author Summary</B></P><P>The biology of human adenoviruses has been studied extensively; however, much less is known about the replication and pathogenesis of the virus in a permissive host. Our laboratory pioneered the use of Syrian hamsters to study the pathogenesis of human adenoviruses. Syrian hamsters are permissive for species C human adenoviruses, which replicate in these animals and cause illness akin to that in humans. Hereby, we report findings with a new Syrian hamster strain (STAT2 KO hamsters), in which the Type I interferon pathway, an important part of the innate immune response to virus infection, is disrupted. This is the first genetically modified Syrian hamster strain ever reported. We show that these animals are very sensitive to infection with type 5 human adenovirus (Ad5). Ad5 replicates to 100- to 1000-fold higher titers in STAT2 KO hamsters than in wild-type ones, and this increased infection causes enhanced pathology. However, the adaptive immune response to the virus infection seems to be intact with the STAT2 KO hamsters, and surviving animals clear the virus effectively. The data reported here may be of interest to researchers focusing on adenoviruses, and also to those who utilize the Syrian hamster as their animal model for other purposes.</P></▼2>

Ecological and Physiological Studies of the Antarctic Limpet Nacella concinna in King George Island

Hua Lu(류화),Mingyuan Zhu(쥬밍얀),Baoling Wu(우바올린) 한국해양과학기술원 1994 KOREAN JOURNAL of Polar Research Vol.5 No.2

Numerical and experimental investigations on the cavitation characteristics of a high-speed centrifugal pump with a splitter-blade inducer

XiaoMei Guo,Linhang Zhu,ZuChao Zhu,BaoLing Cui,Yi Li 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.1

A high-speed centrifugal pump with a splitter-blade inducer is investigated in this work. The flow with rotating cavitation is numericallysimulated, external characteristics are subjected to experimental tests, and the internal flow is visualized. These procedures are conductedto obtain the pressure, velocity, and vapor volume fraction distribution in the inducer and the impeller of the centrifugal pump. Bubble occurrence, development, and collapse are also observed. The predicted H-Q and η-Q curves agree with the experimental resultsof external characteristics. The calculated vapor volume fraction also agrees with the experimental results obtained from the visualizationsystem. The mechanism of bubble evolution and the anti-cavitation performance of the high-speed centrifugal pump with a splitter-bladeinducer are clearly elucidated.

Weak compressibility effects on the pressure fluctuation at RSI in a high-speed centrifugal pump

Shaolong Wang,Xiaoping Chen,Xiaojun Li,BaoLing Cui,Zu-chao Zhu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.10

This study presents large eddy simulation of high-speed centrifugal pump at approximate quarter load (0.23 Q d ) and design load (Q d ) conditions. Two liquid models, including weak compressible and incompressible assumptions, are considered to investigate the weak compressibility effects (WCE) on the pressure fluctuation at rotor-stator interaction (RSI). Researches show that the performance is slightly increased by the WCE at both the flow rates, which deviate from the experimental data within 5 %. There is a phase deviation between the pressure fluctuation of the two assumptions. The amplitudes of pressure fluctuation and pressure spectra are affected by the WCE, especially in the guide vane channel far away from the tongue. The first and second frequencies of pressure spectra are 12 and 6 times the rotation frequency, respectively, which are insensitive to the WCE. The influence of WCE on the pressure fluctuation and pressure spectra is significant at 0.23 Q d and gradually weakened at Q d .

Numerical simulation and analysis of flow characteristics in the front chamber of a centrifugal pump

Yang Wu,Xiaoping Chen,Hua-Shu Dou,Lulu Zheng,ZuChao Zhu,BaoLing Cui,Boo Cheong Khoo 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.11

We performed numerical simulations to study the flow characteristic in a centrifugal pump based on the RANS equations and the RNG k-ε turbulent model. The flow field, including the front and back pump chambers, the impeller wear-ring, the impeller passage, the volute casing, the inlet section and outlet section was calculated to obtain accurate numerical results of fluid flow in a centrifugal pump. The flow characteristic was studied from the internal flow structure in pump chambers, the radial velocity at impeller outlet as well as the pressure inside of the pump, the circumferential velocity and the radial velocity in front pump chamber. The variation of flow parameters in internal flow versus flow rate in the centrifugal pump was analyzed. The results show that the overall performance of the pump is in good agreement with the experimental data. The simulation results show that the distribution of flow field in the front pump chamber is axial asymmetry. The energy dissipation at the impeller outlet is larger than other areas. The distribution of the circumferential velocity and that of radial velocity are similar along the axial direction in the front pump chamber, but the distribution of flow is different along the circumferential and the radial directions. It was also found that the vorticity is large at the impeller inlet compared with other areas.

H₂O Adsorption/Desorption in MOF-74: <i>Ab Initio</i> Molecular Dynamics and Experiments

Li, Yunsong,Wang, Xinjiang,Xu, Dongyan,Chung, Jae Dong,Kaviany, Massoud,Huang, Baoling American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.23

<P>Using density functional theory based molecular dynamics with the tight-binding approximation and experimental characterization, the H<SUB>2</SUB>O vapor adsorption/desorption processes in Zn-MOF-74 and the corresponding influence on the lattice dynamics were investigated. It was found that the Zn sites are preferred for H<SUB>2</SUB>O adsorption, and they even allow for the adsorption of multiple H<SUB>2</SUB>O molecules on the same site, making it possible to form stable H<SUB>2</SUB>O cluster at low temperatures. The adsorption heats of different adsorption processes were predicted, and the possibility of H<SUB>2</SUB>O cluster formation under vapor exposure at low and room temperatures was explored. The first adsorbed H<SUB>2</SUB>O can only be dissociated at elevated temperatures, therefore reducing the cyclic uptake near the room temperature. The vibrational spectra of the lattice and adsorbed H<SUB>2</SUB>O were also calculated using molecular dynamics simulation to illuminate the variation of lattice dynamics during the adsorption. The framework was found to be stable after water vapor exposure near room temperature but may start to collapse at around 570 K. X-ray diffraction and H<SUB>2</SUB>O adsorption isotherm measurements have been conducted to verify the theoretical predictions, and good agreements are found.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-23/acs.jpcc.5b02069/production/images/medium/jp-2015-02069m_0008.gif'></P>