Article
Engineering, Mechanical
Theresa Trummler, Steffen J. Schmidt, Nikolaus A. Adams
Summary: In this study, we numerically investigate the erosion potential of a cavitating liquid jet using high-resolution finite volume simulations. A barotropic equilibrium cavitation approach embedded into a homogeneous mixture model is employed as the thermodynamic model. The effects of collapsing vapor structures are resolved by considering full compressibility. Two different operating points with different cavitation intensities are analyzed, and their erosion potential is estimated and compared using various methods including collapse detection, maximum pressure distribution on the wall, and a new method of generating numerical pit equivalents. The data of numerical pit equivalents is analyzed in detail and compared with experimental data. Furthermore, a comprehensive grid study is presented for both operating points.
Article
Engineering, Mechanical
Mohammad Hossein Arabnejad, Urban Svennberg, Rickard E. Bensow
Summary: The paper proposes a numerical method based on energy description to assess the risk of cavitation erosion, with two improvements compared to other methods. Validation with experimental data shows good agreement between predicted high erosion risk areas and experimental erosion patterns. The method can also be used to study the relationship between cavity dynamics and cavitation erosion risk.
Article
Engineering, Marine
Linlin Geng, Desheng Zhang, Jian Chen, Oscar De la Torre, Xavier Escaler
Summary: This study focuses on simulating unsteady cavitation flow around a hydrofoil and evaluating erosion power predicted by different erosion risk indicators. The research shows that indicators based solely on rapid pressure variations or time derivatives of flow properties are not effective in capturing erosion in certain areas.
Article
Mechanics
Ebrahim Ghahramani, H. Strom, R. E. Bensow
Summary: Cavitating flows involve vapour structures with various length scales, highlighting the importance of accurately estimating small-scale cavities. A hybrid cavitation model that combines a mixture model with a Lagrangian bubble model has been developed to capture multi-scale dynamics and interactions between vapour structures and the continuous flow. This approach shows considerable improvements in predicting large cavities and capturing small-scale structures, even with lower mesh resolution.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Mechanical
Janusz Steller
Summary: The author proposed a fractional approach to model cavitation erosion kinetics over two decades ago in response to issues in material resistance assessments from the International Cavitation Erosion Test project. The current status, potential, and limitations of the methodology were summarized in a paper published by Wear in 2020, along with details of the computational algorithm and examples illustrating the methodology description. Prospects for further development of the methodology are discussed in the paper.
Article
Energy & Fuels
Genmiao Guo, Zhixia He, Qian Wang, Ming-Chai Lai, Wenjun Zhong, Wei Guan, Jiangquan Wang
Summary: This study investigates the impact of needle motion on the evolution of in-nozzle cavitation regimes, revealing different characteristics of needle and hole connecting string cavitation at low and high needle lifts. The formation of both types of string cavitation is strongly influenced by the structure and intensity of in-nozzle vortex flow.
Article
Engineering, Marine
Cagatay Sabri Koksal, Onur Usta, Batuhan Aktas, Mehmet Atlar, Emin Korkut
Summary: This study presents validation simulations of the KCD-193 model propeller focusing on performance, cavitation, and erosion properties. Computational fluid dynamics (CFD) techniques using RANS and DES models were applied to investigate wake effects on cavitation and erosion intensity. Results showed that the RANS model was more suitable for predicting erosion intensity compared to the DES model, and a decrease in cavitation number did not always result in increased erosion intensity, highlighting the need for further research.
Article
Chemistry, Multidisciplinary
Wenqiang Dong, Ligang Yao, Weilin Luo
Summary: A numerical simulation of a submerged angular cavitation nozzle is performed using CFD technique with a multiphase mixture model, cavitation model, and RNG k-epsilon turbulence model. The effects of the contraction part, parallel middle part, and expansion part on velocity and vapor volume fraction are studied. The results show that optimizing the nozzle structure can improve cavitation effect, which is verified by experimental data.
APPLIED SCIENCES-BASEL
(2023)
Article
Chemistry, Multidisciplinary
Andrea Grisafi, Jigyasa Nigam, Michele Ceriotti
Summary: The principle of electronic nearsightedness governs the behavior of condensed matter and supports machine-learning schemes for predicting quantum mechanical observables. A multi-scale approach combining local and non-local information overcomes limitations in capturing a wide range of physical effects. The model construction's data-driven nature allows for tackling various delocalized and collective effects in different fields such as molecular physics, surface science, and biophysics.
Article
Mechanics
Wei Zhang, Bing Zhu
Summary: Cavitation is a known source of erosion in engineering areas such as fluid machinery and ship propulsion. Erosion damage caused by cavitation bubble collapse can lead to extreme failure events, making it important to study the dynamics of cavitation hydraulic structure for cavitation erosion.
JOURNAL OF HYDRODYNAMICS
(2022)
Article
Engineering, Marine
Tengfei Cai, Leonardo P. Chamorro, Fei Ma, Jian Han
Summary: The impact of nozzle lip geometry on the characteristics of cavitation cloud induced by self-excited cavitating waterjets (SECJ) is investigated experimentally. The results show that a nozzle lip with a short throat and a whistle can increase the volume of cavitation cloud, reduce the shedding frequency, extend the effective standoff distance, and enhance the cavitation erosive ability.
Article
Thermodynamics
A. Bel Hadj Taher, H. Kanfoudi, R. Zgolli
Summary: This article presents a new numerical approach to predict the mechanical impact of the implosion of a cloud of bubbles in hydraulic machines, aiming to determine the damage mechanisms and estimate the impact pressure near the surface. The results show good agreement with experiments and suggest that erosion is caused by secondary implosions rather than the cloud of bubbles.
JOURNAL OF APPLIED FLUID MECHANICS
(2022)
Article
Mechanics
Zhixia He, Wei Guan, Chuqiao Wang, Genmiao Guo, Liang Zhang, Manolis Gavaises
Summary: Vortex-induced cavitation is developed in high pressure fuel injector equipment, which is related to local flow turbulence and can be improved in prediction accuracy by adopting different turbulence models and mass transfer cavitation models.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2022)
Article
Engineering, Multidisciplinary
Lu-Wen Zhang, Jia-Yu Ye
Summary: The challenge of material surface damage caused by high-frequency, high-pressure jets due to cavitation is a significant concern. In order to better understand the physical mechanisms of cavitation-induced cyclic impact, a multi-field-coupling framework was developed. This framework includes important processes such as polymer deformation, thermal and strain softening, and damage evolution, and allows for accurate simulation and study of this phenomenon.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2023)
Article
Engineering, Mechanical
Huanlong Liu, Zeping Cao, Chixin Xie, Guanpeng Chen, Dafa Li, Jiawei Wang
Summary: By studying methods to improve the erosion ability of cavitation jets under nonsubmerged condition, it is found that the annular cavitation nozzle can effectively enhance the cavitation effect in the atmosphere domain, leading to stronger cleaning and derusting capabilities compared to high-pressure nozzles. The enhanced effect mainly comes from the collapse of cavitation bubbles, demonstrating the potential for expanding the application of cavitation nozzles.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE
(2021)
Article
Engineering, Marine
Shun Xu, Xin-ping Long, Bin Ji, Gui-bin Li, Yong-liang Xiong
Summary: This paper investigates the vortex-cavitation interaction in the blade tip region through experimental observation and numerical calculation. The evolution of TLVC is analyzed using high-speed photography, and the TLV core center is identified using the Liutex method. The flow along the blade is divided into three regimes based on the TLV core center location and TLVC development: stable cavitation, unstable cavitation, and non-cavitation flow. Both the tip leakage flow (TLF) and main flow have effects on the TLV intensity and trajectory. Analysis of the vorticity transport equation reveals that the circumferential dilatation and axial vortex stretching terms play a significant role in vorticity production and relocation in a rotating frame.
SHIPS AND OFFSHORE STRUCTURES
(2023)
Article
Mechanics
Ming-zhe Zhou, Zi-yang Wang, Xiao-rui Bai, Huai-yu Cheng, Bin Ji
Summary: A multi-scale Euler-Lagrange method is used to study turbulent cloud cavitating flow around a Clark-Y hydrofoil. Macroscopic cavitating structures are simulated using the volume of fluid (VOF) approach, while micro-scale bubbles are modeled using the Rayleigh-Plesset equation and bubble motion equation. The numerical results agree well with experimental data and show clear transitions between different scales of structures. The statistical analysis investigates the evolution of microscopic bubble behaviors.
JOURNAL OF HYDRODYNAMICS
(2023)
Article
Mechanics
Xincheng Wang, Xiaorui Bai, Huaiyu Cheng, Bin Ji, Xiaoxing Peng
Summary: This paper investigates the effect of gap size on the inception of tip leakage vortex cavitation (TLVC) with a hybrid Eulerian-Lagrangian model. Good agreement is achieved between the simulation results and experimental data for velocity distributions around the TLV, bubble motion, and its size oscillations. The paper provides an insight into the mechanism of TLVC inception through the flow characteristics in the TLV core region, which is helpful for controlling TLVC inception in engineering designs.
Article
Mechanics
Lin-feng Deng, Yun Long, Huai-yu Cheng, Bin Ji
Summary: The present paper investigates the turbulent cavitating flow around the Clark-Y hydrofoil with special emphasis on the influence of cavitation models by verification and validation (V&V) method. The results indicate that the three cavitation models can properly reproduce the cavitation evolutions. The verification and validation procedure is involved to quantitatively assess the accuracy of these three cavitation models. In addition, ZGB model exhibits the highest overall accuracy among the three models, which further verifies its wide applicability.
JOURNAL OF HYDRODYNAMICS
(2023)
Article
Engineering, Marine
Yongshuai Wang, Chaohui He, Xincheng Wang, Huaiyu Cheng, Bin Ji
Summary: This numerical study investigates the effects of skew angle on cavitation and the induced low-frequency pressure fluctuations. The numerical results show good agreement with available experimental data. The skew angle has a significant impact on both cavitation dynamics and pressure fluctuations. As the skew angle increases, the dominant cavity type changes gradually from sheet cavitation to tip vortex cavitation, and the cavitation on the blade passing through the wake flow is delayed. Fast Fourier Transforms combined with Wavelet Transforms are used to explore the relationship between cavity volume acceleration and pressure fluctuations for different skew angles. The low-frequency pressure fluctuations around the propeller are mainly related to the first blade passing frequency (BPF) and its harmonics. The collapse of sheet cavities enhances the interaction of low BPF components, while the collapse of tip vortex cavities has the opposite effect. Moreover, large skew angles weaken the interaction of low BPF components, leading to a reduction in low-frequency pressure fluctuations.
Article
Green & Sustainable Science & Technology
Zanao Hu, Yongguang Cheng, Demin Liu, Hongyu Chen, Bin Ji, Jinghuan Ding
Summary: To cope with the challenge of frequent condition changes and operation under part loads in pumped storage units for new energy sources, a new design approach is proposed for pump-turbine runners. A multi-objective optimization strategy is employed to optimize the blade control parameters, such as blade loading and blade lean angle, to enhance efficiency, anti-cavitation, and stability. The study evaluates the impact of control parameters on runner performance and concludes the runner geometric characteristics for different optimizing priorities. The research contributes by providing an effective optimization design process for wide output pump-turbine and revealing the relationship between runner geometric characteristics and performance.
Article
Mechanics
Ziyang Wang, Huaiyu Cheng, Bin Ji, Xiaoxing Peng
Summary: The inner structure and formation mechanism of cloud cavitation around a twisted hydrofoil were numerically investigated using a multi-scale method. A homogeneous mixture model and a Lagrangian model were employed to capture the macroscopic vapor structures and track the microbubble behavior respectively. The study revealed that the shear layer at the liquid-vapor interface played a crucial role in bubble formation, leading to two distinct bubble size spectra. The collapse of the cloud cavity resulted in the generation of a mass of tiny bubbles as well as a significantly greater number of larger bubbles.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2023)
Article
Engineering, Marine
Mohan Xu, Huaiyu Cheng, Bin Ji, Xiaoxing Peng, Mohamed Farhat
Summary: Large eddy simulations are used to investigate the scale effect of tip vortex cavitation (TVC) around an elliptical hydrofoil. The results show that TVC intensity increases significantly with an increase in scale ratio or incoming velocity. Two mechanisms, the roll-up of boundary layer and the interaction between tip vortex, secondary vortex, and trailing vortex, are proposed to explain the scale effect of TVC. In addition, it is found that TVC is stronger in large scale compared to small scale, indicating that equating velocity-induced scale effect with scale-ratio-induced effect may not be reasonable.
Article
Engineering, Marine
Mohan Xu, Huaiyu Cheng, Bin Ji, Xiaoxing Peng
Summary: This paper presents a theoretical derivation of the force acting on slender bodies arranged along the hydrofoil span. It explains the theoretical relationship between the vortex circulation and the maximum bound circulation around the hydrofoil. The paper proposes a new prediction formulation based on hydrofoil load and validates it with numerical simulations. The results confirm the accuracy of the prediction formulation.
Article
Mechanics
Xiaotao Zhao, Ziyan Wang, Xiaorui Bai, Huaiyu Cheng, Bin Ji
Summary: This paper presents a compressible cavitation model that better predicts the collapse behavior of cavitation. The study reveals that shock-induced pressure pulses play a more important role in flow features, and the pulsating pressure exhibits non-Gaussian nature.
Article
Engineering, Mechanical
Ziyang Wang, Huaiyu Cheng, Rickard E. Bensow, Xiaoxing Peng, Bin Ji
Summary: This study investigates the cavitation erosion risk on a twisted hydrofoil using a hybrid Eulerian-Lagrangian solver. A combination of the volume of fluid method and the discrete bubble model is employed to accurately identify high erosion risk regions and evaluate the distribution and intensity of impact pressures from bubbles. The study also analyzes the hydrodynamic mechanisms of cavitation erosion, revealing that the highest erosion risk occurs in areas where primary shedding occurs and that high impact pressure bubbles concentrate around the edges of the shedding cavity.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
