Article
Physiology
Peng Wu, Jiadong Huo, Weifeng Dai, Wei-Tao Wu, Chengke Yin, Shu Li
Summary: This study optimized the hydraulic and hemolytic performance of an inhouse centrifugal maglev blood pump with a secondary flow path by varying major design variables to reduce turbulence and secondary flow intensity. By changing blade angles, blade thickness, and position of splitter blades from a baseline design, turbulent intensities were reduced and the pump model's hydraulic and hemolytic performance significantly improved. Computational fluid dynamics (CFD) combined with hemolysis models were used for evaluation, with a hydraulic test conducted to validate CFD results on hydraulic performance.
FRONTIERS IN PHYSIOLOGY
(2021)
Article
Mechanics
Dmitriy Zhigunov, Roman O. Grigoriev
Summary: This paper presents new classes of unstable recurrent solutions of the two-dimensional Euler equation with periodic boundary conditions. These solutions resemble the recurrent solutions of the Navier-Stokes equation, known as exact coherent structures. The Euler equation solutions come in infinite-dimensional continuous families, are connected to different types of solutions, and exhibit weak instability, leading to the frequent occurrence of these solutions in fully developed turbulence.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Thermodynamics
Arihant Sonawat, Sung Kim, Sang-Bum Ma, Seung-Jun Kim, Ju Beak Lee, Myo Suk Yu, Jin-Hyuk Kim
Summary: This study investigates the pressure pulsation issues of double suction centrifugal pumps using CFD methods, identifying the most effective impeller stagger angle for reducing pulsations and exploring the combination of split volute arrangement to suppress pressure pulsations.
Article
Chemistry, Multidisciplinary
Seongbin Hong, Jophous Mugabi, Jae-Ho Jeong
Summary: This study analyzed the 3-dimensional vortex structures of an air supply device in hydrogen fuel cell electric vehicles (FCEVs) using critical-point theory and probabilistic definitions. The behavior of the tip leakage, hub separation, and horseshoe vortex structures was found to significantly impact the aerodynamic performance of the centrifugal compressor. After optimizing the compressor design, the average pressure difference improved by 1.47% of the entire flow rate.
APPLIED SCIENCES-BASEL
(2022)
Article
Environmental Sciences
Ye Yuan, Weihong Gong, Guojun Wang, Jun Wang
Summary: Pitch motion has a significant impact on the performance characteristics of centrifugal pumps, causing a decrease in head and changes in the flow characteristic curve. In low-flow conditions, pitch motion can lead to the appearance of a hump zone in the flow characteristic curve. Furthermore, pitch motion intensifies the instability of vortex flow and results in periodic variations in fluid-induced pressure.
Article
Mathematics, Applied
Sergei Iakunin, Luis Vega
Summary: One of the characteristic features of turbulent flows is the emergence of vortices that interact, deform, and intersect, generating chaotic movement. The evolution of a pair of vortices, such as condensation trails of a plane, can be seen as a basic element of turbulent flow. This study focuses on the reconnection phenomena and the structures that emerge from it, using a new model based on an infinitely thin vortex to observe the chaotic movement of the vortex center line.
JOURNAL OF NONLINEAR SCIENCE
(2023)
Article
Engineering, Mechanical
Chengshuo Wu, Wenqi Zhang, Peng Wu, Jiale Yi, Haojie Ye, Bin Huang, Dazhuan Wu
Summary: The effects of modifying the blade pressure side (PS) on unsteady pressure pulsation and flow structures in a low specific speed centrifugal pump were studied using experimental and computational fluid dynamics (CFD). Results showed that the blade PS modification could significantly alleviate the amplitude of pressure pulsation by achieving a more uniform energy distribution at the impeller outlet. The change in internal flow structure improved the uniformity of circumferential velocity distribution downstream of the impeller outlet, leading to a decrease in pressure fluctuation amplitude in the volute.
JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME
(2021)
Article
Engineering, Chemical
Kirill Mikhaylov, Stelios Rigopoulos, George Papadakis
Summary: The study combines reduced order modeling and system identification to reconstruct the temporal evolution of large-scale vortical structures behind the blades of a Rushton impeller. The results demonstrate that even using the velocity time signal from a single sensor point, the first pair of modes can be reconstructed well. Increasing the number of sensor points improves accuracy and stability, leading to better reconstruction of the second pair of POD modes. The estimator derived at Reynolds number 600 shows robustness when applied to flows at Reynolds numbers 500 and 700.
Article
Mechanics
Andre N. Souza, Tyler Lutz, Glenn R. Flierl
Summary: We analyze a class of stochastic advection problems by conditionally averaging the passive tracer equation with respect to a given flow state. We obtain expressions for the turbulent diffusivity as a function of the flow statistics spectrum. The ensemble average turbulent flux is expressed as a linear operator that acts on the ensemble average of the tracer.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Computer Science, Interdisciplinary Applications
Jiantao Zhao, Ji Pei, Jianping Yuan, Wenjie Wang
Summary: To achieve energy savings in multistage centrifugal pumps, a return channel is used instead of the original inter-stage flow channel structure. A single-objective optimization work is conducted using high-precision numerical simulation, design variable dimensionality reduction, and machine learning to determine the optimal geometric parameters. The study investigates the influence of 15 design variables and selects seven with high-impact factors as the final optimization variables. The findings show that the optimized model increases efficiency by 4.29% at 1.0Q(d) and eliminates performance degradation under overload conditions (maximum efficiency increase of 14.72% at 1.3Q(d)). Internal flow analysis confirms that the optimization scheme improves turbulence kinetic energy distribution and reduces unstable flow structures in the multistage centrifugal pump.
JOURNAL OF COMPUTATIONAL DESIGN AND ENGINEERING
(2023)
Article
Mechanics
Jiahan Wang, Joern Sesterhenn, Wolf-Christian Mueller
Summary: This study compares different structure detection schemes in two-dimensional turbulence and examines their effects on the inverse cascade. The results show that coherent structures contribute less to the cross-scale flux of energy, but play a significant role in deforming the energy spectrum at large scales.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Green & Sustainable Science & Technology
Puyu Cao, Rui Zhu, Gang Yin
Summary: This paper presents a numerical simulation study on distorted suction flow caused by an inlet elbow installed upstream of a centrifugal pump, with a focus on the interactions between impeller and inlet distortion leading to upstream disturbances. By analyzing the velocity, pressure and swirling strength, the formation and effects of vortex bubbles on the inner wall were identified, shedding light on the mechanism of upstream disturbances.
Article
Chemistry, Multidisciplinary
Denghao Wu, Songbao Yao, Renyong Lin, Yun Ren, Peijian Zhou, Yunqing Gu, Jiegang Mou
Summary: The study conducted a numerical investigation of a double-blade centrifugal pump, revealing the presence of large vortices at low flow rates and high vorticity near the blade trailing edge and volute tongue.
APPLIED SCIENCES-BASEL
(2021)
Article
Green & Sustainable Science & Technology
Hamidreza Bozorgasareh, Javad Khalesi, Mohammad Jafari, Heshmat Olah Gazori
Summary: A new impeller design with innovative shrouds is introduced to improve the pressure head and efficiency of semi-open centrifugal pumps. Experimental and numerical analysis show that the impeller with 90-degree bladelets can enhance the hydraulic performance of a semi-open centrifugal pump to a level close to that of a closed impeller.
Article
Mechanics
Farid Aligolzadeh, Markus Holzner, James R. Dawson
Summary: The interaction between small-scale vortical structures and the surrounding fluid is investigated using experimental and numerical data. The flow across the boundary of vortex structures is examined, and a non-Gaussian distribution of entrainment velocity is observed. The enstrophy transport equation is analyzed to quantify the inviscid and viscous components of the entrainment/detrainment process. The study also compares the findings with the Burgers vortex model.
JOURNAL OF FLUID MECHANICS
(2023)