bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative study of different cavitation erosion assessment methods in cavitating flow around a Delft Twist hydrofoil
Authors: Huang Jiale , Deng Linfeng , Ji Bin , Cheng Huaiyu 
Published: March 2024

Abstract
Cavitation erosion is a common phenomenon in hydraulic machines, which severely threatens their stable operation. Although several methods for erosion risk assessment have been proposed, few researchers work on the comparative study of different cavitation erosion assessment methods. Therefore, this study utilized Large Eddy Simulation (LES) combined with Zwart-Gerber-Belamri (ZGB) cavitation model to conduct the numerical simulation for the cavitating flow around a Delft Twist hydrofoil. The Erosive Power Method (EPM), Improved Gray Level Method (IGLM) and Energy Conservative Method (ECM) are employed separately to evaluate the cavitation erosion. Among the three results, the EPM results cannot accurately predict erosion in the middle region and trailing edge region, where the U-shaped vortex collapse. The results of IGLM and ECM can predict the erosion in the middle region and erosion caused by the U-shaped vortex at the trailing edge. IGLM still needs artificial thresholds, while ECM emphasizes areas with higher cavitation risk by amplifying parameter n. The ECM method is more objective from the simulation results.
Numerical implementation and verification of the Zwart-Gerber-Belamri cavitation model with the consideration of thermodynamic effect
Authors: Ezekoye David , Zheng Zhi-Ying , Wu Jian 
Published: March 2024

Abstract
In the world of pumps, turbopumps, and industrial applications, the absorption and release of latent heat in high-temperature zones play a pivotal role in the cavitation process. This phenomenon exerts a profound influence on system performance, especially when handling hot and cryogenic fluids, which are particularly susceptible to thermodynamic influences. The pressing need arises for a robust computational approach to address the intricacies of thermodynamic effects on cryogenic cavitation. The study at hand introduces a modification to the Zwart-Gerber-Belamri cavitation model, incorporating thermodynamic considerations to simulate quasi-steady cavitating flow around a NACA0015 hydrofoil. The SST k-ε turbulence model and homogeneous mass transfer cavitation model are employed to account for thermal effects, while the Clausius-Clapeyron equation is utilized to adjust the saturated vapor pressure within the cavitation model. Comparing the results with experimental data from Cervone et al. [1], especially in the thermal domain, reveals congruence in the estimated pressure and temperature drop (ΔT) within the cavity under varying free stream temperature conditions. Notably, thermodynamic effects exert a significant influence on cavitation dynamics during the phase-change process, potentially hindering or delaying cavitation in hot and cryogenic fluids. This enhanced cavitation model offers a marginally improved prediction of cavitation in water.
Contribution of interphase force curl to rigid vorticity transport in water-sand two-phase flow with fine particles
Authors: Chen W H , Wang F J , Wang C Y , He C X , Chen X , Tang X L 
Published: March 2024

Abstract
Rigid vorticity transport equation is an effective tool for describing the intuitive vortex evolution characteristics. Compared to single-phase flows, the curl of the interphase force appears as a new source term of this equation under the condition of multiphase flows, which may cause additional contributions. However, the effects of the interaction force on rigid vorticity transport in water-sand two-phase flows with fine particles are still unclear. In this article, taking the Karman vortices induced by a hydrofoil as a typical case, the distributions of rigid vorticity in single-phase flows and two-phase flows were compared, and the dynamics mechanism of the dominant interaction force was analyzed. The following notable results are obtained. Firstly, the drag force can be regarded as the dominant interaction force. Secondly, the effect of the drag force on a vortex tube is mainly manifested as inducing normal strain and the contribution is relatively low. Thirdly, there are only slight differences in the waveform, amplitude, frequency of rigid vorticity and apparent vortical structures between the single-phase flows and the fine-particle two-phase flows. These new findings are helpful for understanding the vortex evolution in water-sand two-phase flows with fine particles.
Numerical investigation of partial cavitation in a Venturi tube by Eulerian-Lagrangian multiscale modelling
Authors: Zhou Zhizhong , Li Linmin , Xuan Xiaoxu , Chen Songying , Yoon Joon Yong , Sun Xun 
Published: March 2024

Abstract
The cavitating flow in a Venturi tube has a complex flow structure. In this paper, the partial cavitation in an axisymmetric Venturi tube, dominated by bubbly shock, is investigated by utilizing Eulerian-Lagrangian multiscale modelling. The unsteady partial cavitation is simulated by Large Eddy Simulation coupled with the Volume of Fluid and the Discrete Bubble Model. The numerical results show a well agreement with the high-speed photography. Through a comprehensive analysis of the development and transportation of macro cavities and micro bubbles, a detailed explanation of the cavity shedding process triggered by bubbly shock is provided. The results highlight the precise capability of the multi-scale method in elucidating the intricate flow field induced by partial cavitation. The findings may pave the way for the further investigations on the underlying mechanisms of partial cavitation, fostering a deeper understanding of bubbly shock dominated cavitating flow.
Research on cavitation characteristics of water-jet pumps with different blade tip clearances based on entropy production theory
Authors: Fei Z Y , Guo Q , Huang X B , Ming X 
Published: March 2024

Abstract
Water-jet pumps are widely used in ship and other power fields. An axial-flow water-jet pump is studied with different size of tip clearance, and the cavitation characteristics are studied based on the theory of entropy production. Modified SST with curvature correction and modified Zwart cavitation model based on vortex identification are adopted, and the numerical calculation method is verified by reference experiments of a model pump. Under normal operating conditions, the results show that when the size of the tip clearance varies from 1.6‰ to 7.9‰ of the impeller diameter, efficiency takes a linear decrease accordingly, and the total entropy production increases linearly. At the same time, the main energy dissipation mode changes from wall dissipation to turbulent dissipation. Under severe cavitation conditions the total entropy production adds 30%. The water-jet pump shows that the entropy production in the impeller section is the highest, which accounts for 40%-50% and is closely related to the vortex and cavitation flow field in the tip clearance of the impeller. The tip leakage vortex region causes cavitation, but significant energy dissipation occurs at the outer edge of leakage vortex and on the nearby wall area, while the attached cavitation on the blade surface is the main source of turbulent dissipation.
Frictional pressure drop of two-phase flow in a horizontal tube under low void fraction
Authors: Feng C N , Miyagawa K , Kawahara T , Katayama Y 
Published: March 2024

Abstract
The frictional pressure drop of air-water two-phase flow is a crucial parameter in hydrodynamic calculations. Solving for precisely calculating frictional pressure drop in it remains a significant challenge due to the various factors affecting two-phase flow characteristic. Currently, various scholars have proposed multiple frictional pressure drop prediction models of two-phase flow. Typically, these models exhibit great errors under low void fraction. To more accurately predict the frictional pressure drop of two-phase flow under low void fraction, this paper experimentally investigated the flow characteristics of air-water two-phase flow in a horizontal tube. The flow rates for water and air are 3-6 kg/s and 0.0004-0.003 kg/s, respectively. The void fraction ranged from 0 to 0.07%. The experimental data and flow patterns of two-phase flow were analyzed, and these data was compared with commonly used frictional pressure drop prediction model of two-phase flow. The results indicated that: (1) Within the scope of this paper, two-phase flow pattern observed include bubbly flow and slug flow. With changes in the void fraction, the number of bubbles and the length of slugs have undergo alterations; (2) All three commonly used prediction models underestimated the frictional pressure drop under low void fraction. Therefore, Considering more influencing factors to improve the accuracy of prediction model is the next research direction. This research has showed the limitations of existing prediction models and emphasized the importance of research on frictional pressure drop of two-phase flow.
Numerical analysis of flow instability with vortex cavitation in venturi tube
Authors: Nakashima T , Enomoto Y , Nakamura T 
Published: March 2024

Abstract
The swirling flow with cavitation can cause pressure pulsations in a draft tube of a hydro turbine at off-design operating conditions. Especially at the full load condition, the cavitation volume may fluctuate greatly, causing pressure pulsations with flow rate fluctuations known as cavitation surge throughout the hydraulic system. The cases that predicted the phenomenon qualitatively using the CFD analysis have been reported previously, whereas the methods to predict the cavitation volume and the fluctuation frequency in the cavitation surge condition quantitatively have not yet been established. Therefore, in this study, unsteady CFD analysis was conducted for the experimental apparatus that simulates the flow in the draft tube downstream of a runner using the stationary guide vane and the venturi tube. In CFD analysis, the influence of the turbulence models by using LES and SST and the influence of the number of meshes in LES simulation were investigated. It was founded that LES simulation captured the vortex generation finely and improved the prediction accuracy of the cavitation volume than SST simulation. On the other hand, it was founded that too fine mesh has a small effect on the prediction accuracy of the cavitation volume, although the resolution of the vortex is improved.
Structure optimization of DTH hammer piston based on RBF neural network and WSO algorithm
Authors: Wang Jiangang , Feng Ding , Liang Jinli , Zhao Yu 
Published: March 2024

Abstract
To address the issue of piston fracture due to insufficient strength in the Down-The-Hole (DTH) hammer. The effect of the pressure state of the gas chamber on the piston motion is considered. A piston motion model is established based on the steady flow energy equation and the working principle of the piston. The finite element method is used to analyze the dynamic response of the piston during the impact of the drill bit. RBF neural network is employed to construct a surrogate model for the relationship between piston structural parameters (front-end diameter, front-end length, and center bore) and piston strength and performance (impact energy, frequency, and gas consumption). By combining this model with the white shark optimization search algorithm, the design of the DTH hammer’s piston structure parameters is optimized. The minimum piston mass is the objective function. Impact energy, frequency, air consumption and stress are constraint factors. The effect of piston life is considered while meeting rock drilling efficiency. The optimization results show that the stresses in the optimized piston structure are reduced by 13%. The proposed RBF performance prediction model combined with the optimal search algorithm can significantly improve the optimization efficiency.
The design and testing of a high reaction turbine blade profile
Authors: Yang Changzhu , Fan Liyun , Yan Wei , Zhang Hanwen 
Published: March 2024

Abstract
In order to improve the efficiency of high pressure cylinder of 50∼350MW steam turbine and reduce the manufacturing cost, a steam turbine blade profiles are designed. The numerical simulation and test study of the new blade profile are carried out, and the performance of the new blade profile with variable inlet angle and mach number is discussed, and the performance of the new blade profile is improved when applied to stage environment. The results show that the performance of variable inlet angle and variable mach number of the new blade profile is better than that of the original profile. The aerodynamic efficiency of the new blade profile is obviously better than that of the original profile. The blade loss of the new design profile is lower than the original profile, and the aerodynamic efficiency of the new design profile is obviously better than the original profile. The stage test results show that the efficiency of the new design profile increases by about 0.5% compared with that of the original profile.
Turbine performance improvement by the multi-objective optimization for variable nozzle vanes of turbocharger
Authors: Wang Wantong , Morita Junnosuke , Sakurai Yusei , Ueno Takahiro , Morita Isao , Novo Patxi Garcia , Sakaguchi Daisaku 
Published: March 2024

Abstract
This paper focuses on improving the turbine efficiency of a variable geometry system (VGS) of turbochargers for internal combustion engines. The study investigates the shape optimization of the turbine nozzle vane and impeller of VGS through a meta-model-assisted multi-objective optimization. The design parameters of the optimal solution were compared with the baseline model for data and internal flow field analysis to explore which parameters have an impact on performance improvement. It was found that the optimized trailing edge angle of the nozzle vanes allows the exhaust airflow to reach the impeller with the minimum traveling path, and it contributes to mitigating the mixing loss of the flow to the impeller blade. The optimized impeller blade angle leads to an increase in torque and a higher turbine efficiency (> 5%) with the narrow opening, also ensuring a high mass flow in the wide opening. This outcome can contribute to the design and development of high-performance and low-emission turbocharger systems by optimizing the performance of turbine design parameters simultaneously.
Experimental study on a loop thermosyphon with microencapsulated phase change material suspension
Authors: Tan Zhenyu , Li Xunfeng , Zhou Jingzhi , Huai Xiulan 
Published: March 2024

Abstract
Microencapsulated phase change material suspension (MPCMS) represents an innovative category of functional thermal fluids. This novel working fluid not only preserves the substantial energy density and high latent heat of phase change materials (PCM), but also mitigates the issues related to PCM, including susceptibility to aggregation and low thermal conductivity. This article selects phase change microcapsules with a phase change temperature of 70 °C, and uses pure water as the base liquid to prepare MPCMS as the working fluid for the loop thermosyphon. A series of heat transfer experiments are conducted, and the results are compared with those of pure water experiments. A 135mm*650mm copper loop thermosyphon, is designed and constructed to investigate the effect of various input power on the heat transfer performance. The results show that the addition of MPCMS can reduce the wall temperature by up to 2.9°C and the loop thermal resistance by 6.3%. Compared with water, the loop thermosyphon with MPCMS has better start-up characteristics. The performance of the MPCMS is affected by various parameters, which are interconnected. Particles in close proximity to the wall display erratic movement, fluctuating across different temperature zones, thereby undergoing a continuous cycle of melting and solidification. This study establishes a basis for further investigation into the practical implementation of MPCMS in industries.
Microstructure and properties of 316L cladding layer on Hydraulic support cylinder
Authors: Xu Lin , Zhang Haiyu , Liu Eryong , Zhang Jingli , Jiao Yang , Wang Ming , Zhan Lihua , Tang Yan 
Published: March 2024

Abstract
Scanning speed refers to the motion of the laser beam on the surface of the substrate. The transformation of heat affected zone and microstructure of the matrix were observed by increasing the motion speed and martensite content. The effect of scanning speed on the microstructure and properties of the coating was studied. In addition, the electrochemical properties and hardness of the workpiece are also improved.
Study on the impact of Cr content on the microstructure and properties of Cu-Cr alloys
Authors: Liu Keming , Yang Xilian , Wen Jiahao , Shi Jinke , Xu Jiekai , Zhang Yuhan , Fu Kai , He Xuelong , Shen Zhi 
Published: March 2024

Abstract
Copper has excellent electrical conductivity, but the disadvantages of low strength and hardness limit its application range. In this paper, Cu-XCr (X=5, 7, and 9, where 5, 7, and 9 are all mass percentages) alloys were treated as the object of study; the impacts of Cr contents on the microstructure, Vickers hardness, and conductivity of Cu-XCr alloys were investigated using an XHC-SV2 upright metallographic microscope, a digital display Vickers hardness tester, and a Sigma2008C digital metal conductivity meter; the optimal Cr content was determined by the comprehensive performance parameter Z. The research results showed that the second phase of Cu-XCr alloys contained dendritic, nearly spherical, and other shapes. The size was relatively small, and the distribution was relatively uniform; the Vickers hardness improved and the electrical conductivity declined with climbing Cr content; when X=7, the comprehensive performance parameter Z of Cu-XCr alloys reached a maximum of 6.7×105 HV2·%IACS.
Synthesis of PMM and Synergistic Flame Retardant Effect with Ammonium polyphosphate
Authors: Dong Yanmao , Shen Zhiyang 
Published: March 2024

Abstract
A novel flame retardant poly {[(2-Methyl-acrylic acid 2-(dimethoxyphosphoryloxy)-ethyl ester]-co-[2-Methyl-acrylic acid 2-(trimethoxysiloxy)-ethyl ester]} (PMM) containing dimethoxyphosphoryloxy and trimethoxysiloxy groups in side chains was synthesized. The structure of PMM was characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H NMR), and the thermal performance of PMM was characterized by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The effect of PMM on polypropylene’s flame retardancy and thermal behaviors was investigated by limited oxygen index (LOI), vertical burning test (UL-94), and TG tests. The experimental results indicate that the addition of PMM helps to improve the flame retardancy and thermal stability of PP. When the addition of PMM and APP in PC was 15% and 20%, the LOI value of PC reached 28.4%, and the UL-94 test rating reached V-0 level. The charred structure observed by scanning electron microscopy (SEM) indicated that the char surface for PP/APP/PMM system holds an intumescent char structure compared to neat PP, and the synergy exists in the composites. The PMM slightly decreased the tensile property in terms of strength but increased the elongation at break for PP composites.
High temperature chlorine corrosion resistance of gradient high entropy alloy coatings prepared by high-velocity-oxygen-fuel spraying
Authors: Chu Xi , Hu Shu-sen , Dai Zhen 
Published: March 2024

Abstract
The effect of different gradient structures on the high temperature chlorine corrosion resistance of gradient high entropy alloy coating was studied to improve the service life of the heating surface of a waste-incinerated boiler. NiCrAl ceramic composite coating (NC), high entropy ceramic composite coating (HC), and gradient high entropy alloy coating (TC) were prepared on 12Cr1MoV substrate by high-velocity-oxygen-fuel spraying. The effects of morphology and microstructure of different coatings on thermal shock resistance and high temperature chlorine corrosion resistance were studied. The results indicate that the porosity of NC coating, HC coating, and TC coating decreased in turn. In the thermal shock resistance test from 800°C to room temperature, the average number of thermal shock of TC coating can reach 21. The mass change of TC coating in 650°C high temperature Cl corrosion resistance test is less than 30 mg/cm2 after 50 hours. In summary, the gradient high entropy alloy coating with HEA as the metal bonding phase can improve the density of thermal spraying gradient coating, and enhance the thermal shock resistance and high temperature Cl corrosion resistance of the coating. Based on the comprehensive on-site application results, it can be concluded that the use of high velocity oxygen flame gradient high entropy alloy coating can effectively improve the density, thermal shock resistance, and high temperature Cl corrosion resistance of the thermal spraying gradient coating on the heating surface of the boiler, and has broad application prospects.
Doping of metal into transition metal dichalcogenides PdTe2
Authors: Chen Li , Wang Yanan 
Published: March 2024

Abstract
Rh-doped PdTe2 single crystals were successfully prepared using the solid-state reaction. The change of lattice constants and T
c with increasing Rh content were studied and investigated. It was found that there is a very slight increase of lattice constant c with increasing Rh content. The values of T
c were above 2 K when Rh content is equal to 0.05 and 0.1. The largest T
c was~2.7 K for Rh0.05PdTe2 single crystal. T
c does not increase with increasing x from 0.05 to 0.1. M-T measurement of Rh0.05PdTe2 single crystal with applied magnetic field H perpendicular to the c axis and along and c axis gives evidence of type II superconducting behavior. This study shows Rh doping is a promising method to increase T
c and investigate SC in PdTe2.
Design and Synthesis of Polyacrylamide Quaternary Ammonium Salt with Antibacterial Activity
Authors: Shan Chaoyue , Huang Yongle , Wang Yu 
Published: March 2024

Abstract
Propenamine quaternary ammonium salt (NNDBAB) containing unsaturated bonds was synthesized from propenamine and bromobutane by alkylation reaction. Using NNDBAB as a monomer, PNNDBAB was further self-polymerized by free radical polymerization to produce propenamine quaternary ammonium salt (PNNDBAB). The structure of NNDBAB was characterized by infrared spectroscopy and nuclear magnetic resonance spectroscopy. The antibacterial properties of PNNDBAB were characterized by an antibacterial zone test, minimum inhibitory concentration, and smear plate counting. The results showed that PNNDBAB had good bacteriostatic activity, the diameter of the bacteriostatic zone was 27 mm, the minimum bacteriostatic concentration was 0.5 mg/L, and the bacteriostatic rate of 1wt% was 71.0%. The bacteriostatic effect was significant. The antibacterial effect of PNNDBAB is long-lasting. When added to the emulsion, the antibacterial effect of PNNDBAB can be sustained within 15 days.