bluuebunny/crossref_metadata_2025_split huggingface dataset:
Particle distribution and two-phase flow characteristics of twin-screw pump during solid-liquid transfer
Authors: Wang Zhenhao , Sun Shuaihui , Wu Pengbo 
Published: March 2024

Abstract
The twin-screw pump is a kind of positive displacement machinery with smooth pressure and flow pulsation and strong self-priming ability, which is widely used in the fields of oilfield production, marine engineering, and other fields. However, in the process of conveying liquid-phase media, it is difficult to avoid the inclusion of solid impurities and grit, resulting in wear of the pump casing and rotor, and the pump’s pressurization capacity is reduced or even shut down. At present, the solid-liquid two-phase flow characteristics within the twin-screw pump have not been clarified, which hinders the study of particle wear in the pump. In this paper, a solid-liquid two-phase flow study is carried out on a twin-screw pump through numerical simulation and experimental testing. The distribution of particles with different diameters in the rotor domain with the liquid-phase transport process is explored by simulating the two-phase flow under different differential pressures and particle concentrations. The results show that the particles in the rotor domain are mainly distributed in the region away from the male and female rotor engagement, and the number of particles near the engagement is small but the velocity is higher under the influence of the clearance jets; the elevation of the differential pressure and the particle concentration increase the risk of the particles to collide with the rotor more frequently and at higher velocity; at different particle concentrations, new localized vortices are caused by particle conveying which compared to pure liquid transport, but there are also cases where the original vortices are suppressed. The results will provide a theoretical basis for further research on particle wear characteristics in twin-screw pumps.
Numerical investigation the shape of groove on tip leakage vortex suppression of a NACA0009 hydrofoil
Authors: Wang L K , Mi J Z , Luo X Q , Yao L , Feng J J , Zhu G J , Li C H 
Published: March 2024

Abstract
To investigate the effect of different bionic grooves on the tip leakage vortex, four bionic grooves with different shapes were designed, which are semicircular, rectangular, triangular and trapezoid. The streamline, pressure, vortex strength and turbulence kinetic energy were analyzed to clarify the suppression mechanism. When the groove is arranged, the velocity of vortex center and the area of high-intensity vortex area decrease. The vortex strength in the triangular groove is higher than other groove shapes. The pressure in the center of the tip leakage vortex core increases. The low pressure area reduces obviously, which is the smallest in the trapezoidal groove condition. The turbulent kinetic energy in the main flow field increases, but decreases in the tip clearance. The high turbulent kinetic energy region is divided into small pieces by the bionic groove, which is the smallest in the rectangular groove condition. The bionic groove leads to the decrease in lift-to-drag ratio, which is the largest in the semicircular groove and smallest in the rectangular groove condition.
Study of the effects of modified draft tube with inclined conical diffuser on draft tube and upstream region
Authors: Zhou Xing , Huang Quanshui , Hu Xinyi , Dai Xiangyu 
Published: March 2024

Abstract
Various countermeasures including geometry optimization have been proposed and proved to have a huge impact on flow filed within the draft tube in order to mitigate the vortex rope and the induced pressure fluctuations for Francis turbine under part load operation. However, the effect of these approaches on the hydro-dynamics in upstream region still remains unclear, which is of great significance for the overall performance of the unit. This study aims to explore the influences of modified draft tube with inclined conical diffuser on the pressure fluctuations in whole flow passage. The results reveal that Generation-1 and Generation-2 draft tubes are effective in alleviating pressure fluctuations resided in the draft tube, but the former one would trigger a low-frequency pressure fluctuation with higher amplitude in the runner zone. In addition, the modified draft tube has a very limited effect on the high-frequency pressure fluctuations in the guide vane and vaneless areas. To eliminate the adverse effect of inclined conical diffuser, a design with a transitional section is put forward to smoothly connect the runner zone and inclined conical diffuser. This further developed Generation-2 draft tube presents a reasonably good performance in terms of improving flow stabilities, i.e. alleviating the pressure fluctuations not only in draft tube but also in upstream region such as runner zone. This study provides reference for obtaining a better mitigating effect on pressure fluctuations in the whole turbine flow passage.
Research on the influence of needle roughness of Pelton turbine on flow characteristics
Authors: Meng Han , Zhang Jing , Ge Xinfeng , Huang Jinwei 
Published: March 2024

Abstract
The needle in the jetting mechanism of Pelton turbine may be uneven on the surface of the needle due to the knife marks in the cutting process or the erosion of the sediment in the water flow, resulting in the surface roughness of the needle, which affects the flow at the wall. In order to study the influence of the surface roughness of the needle on the jet flow characteristics, the jet flow characteristics and sediment characteristics of the jetting mechanism under different roughnesses were analyzed in this paper. The results show that the flow characteristics of the smooth wall and the rough wall are obviously contrasted. With the increase of the needle roughness, the jet velocity of the jetting mechanism gradually decreases, the turbulent kinetic energy of the needle surface gradually increases, the shear stress on the needle surface gradually increases, the wear amount gradually increases, the wear area increases, and the efficiency of the jet mechanism with a 1mm roughness wall decreases by about 22.3% compared with the smooth wall.
Performance improvements of vertical axis wind turbines with modified gurney flaps
Authors: Yang P , Chen L , Zhang B X , He C C 
Published: March 2024

Abstract
Plain Gurney flap (PGF), as a passive flow control method, is widely used to improve the aerodynamic performance. Due to the drag penalty, a novel serrated Gurney flap (SGF) is proposed. The numerical simulation is carried out to investigate the effects of GFs on the aerodynamic performance of the NACA0018 airfoil and an associated two-blade rotor of a H-type Vertical Axis Wind Turbine (VAWT). The height of GF ranges from 1.5% to 6% of the airfoil chord length. The results show that the SGF doesn’t exhibit the same lift enhancement as PGF, but lower drag. When the flap height reaches 6% c, the SGF airfoil has the higher lift-to-drag ratio. The 3%-chord-length height of GFs is employed on the rotor and it implies that both PGF and SGF can enhance the output power of VAWT. SGF has superior performance than GF, especially at the TSR>2.5 conditions. At the optimal TSR=3.0, the output power of SGF turbine is 2.7% higher than that of PGF one. The highest improvement of power can reach 13.3% at TSR=4.0.
Experimental study on restraining outflow distortion of a waterjet inlet using vortex generator jets
Authors: Zhou J M , Wang Z J , Chen L , Ma X Q , Dai R 
Published: March 2024

Abstract
The internal flow of the flush-type waterjet intake duct is simulated through an experiment in a low speed wind tunnel. The distributions of static pressure along the intake duct wall and the total pressure in the pump face plane are measured to investigate the influence of the vortex generator jet (VGJ) on the outflow behavior. Test cases were screened by Taguchi method. Experiment results verify a pair of VG jets with a blowing ratio 2 and lateral spacing 4 has the best performance. The inlet’s outflow is improved that total pressure recovery coefficient is raised from 0.712 to 0.771 and uniformity coefficient of axial velocity component from 0.652 to 0.824. The distortion coefficient of total pressure is reduced from 0.381 to 0.177. Vortex generator jet is a promising active flow control for waterjet application.
The research of multi-dimensional flow mapping for proportional flow control valve based on long short-term memory network
Authors: Xu Yue , Yang Gang , Li Baoren 
Published: March 2024

Abstract
The multidimensional flow mapping illustrates the numerical correlation between the flow rate and three pertinent factors, namely spool displacement, valve port pressure difference, and oil temperature. This representation signifies a mapping of three-dimensional inputs to a one-dimensional output. Accurate mapping relationship lays solid foundation for the feasible flow control of the flow control proportional valve. Since the proportional flow control valve is a complex system with high nonlinearity, it is challenging to treat the flow mapping relationship as a simple parameter estimation problem. In this regard, this paper combines the relevant theories of signal processing and deep learning (DL) to propose a novel four-dimensional input-output mapping relationship learning method. This method adopts the long short-term memory (LSTM) network to model the multi-dimensional flow mapping relationship. And for better quality of the data, the initial measurement datasets, contaminated by environmental factors, are processed using a finite impulse response (FIR) filter to reduce noise before training the data. Moreover, the trained model is validated on test datasets. The experimental results shows that the mentioned method can accurately estimate the multidimensional mapping relationship of the proportional flow control valve.
Optimal scheduling for wind-solar-hydro hybrid generation system with cascade hydropower considering regulation energy storage requirements
Authors: Liu Yuanyuan , Guo Pengcheng , Zhang Hao 
Published: March 2024

Abstract
Large-scale integration of renewable energy into the grid can lead to significant changes in the net load, peak-to-valley difference, peak and valley occurrence time of the power system. As a result, the power of hydropower plants must take a rapid adjustment response. Aiming at the coordinated operation of multiple energy sources, such as wind power, solar power, cascade hydropower station and energy storage pumping station, a coordinated scheduling model is proposed which can fully improve the consumption capacity of wind and solar power by aiming at the maximum power generation, minimum net load fluctuation and minimum wind and solar abandonment. Through the configuration of three different pumping station capacities, the influence of energy storage pumping station capacity on the complementary power generation system is analyzed. When the pumping station capacity is large enough, the output of the wind and solar can be completely consumed. The studies show that the cascade power station and pump energy storage regulation have a strong net load filling valley effect, which can effectively reduce the impact of wind and solar access on system operation, maintain the efficient and stable operation of the unit, and ensure the absorption rate of renewable energy.
Analysis of the flow field of kerosene-fueled rotating detonation engine with film cooling
Authors: Li Jingzhe , Yu Jingtian , Li Jianghong , Lei Ying , Yao Songbai , Zhang Wenwu 
Published: March 2024

Abstract
The advance of the rotating detonation engine (RDE) toward practical applications demands the integration of effective cooling schemes. In this study, a three-dimensional simulation of the hydrogen-enhanced kerosene-air RDE with inclined cylindrical film cooling holes is conducted to analyze the influence of the cooling flow on the two-phase rotating detonation flow field based an Eulerian–Lagrangian model. The liquid kerosene is injected at the ambient temperature with hydrogen-assisted combustion enhancement. Results suggest that a stable propagation of the kerosene-fueled rotating detonation wave can be maintained after the introduction of cooling air and the three-dimensional structure of the flow field is analyzed. It is found that the periodic sweeping action of the detonation wave leads to temporary blockages of the film cooling holes, causing interruptions in the outflow of cooling air. Additionally, the investigation highlights the intensified heating and evaporation of kerosene droplets near the outer wall of the RDE, whereas the presence of cooling air prevents the accumulation of kerosene vapor near the outer wall. It is revealed that the film cooling efficiency exhibits a lower value in the vicinity of the fuel injection surface, but gradually increases along the length of the combustion chamber.
Multi-scale mechanical-thermal coupling analysis of multi-layer thermal protection structure of ceramic matrix composites
Authors: Xuan Liang , Yuanhong Wang , Tu Zecan , Jia Yang , Junkui Mao 
Published: March 2024

Abstract
The wall of combustion chamber needs to sustain the extremely high thermal and stress load in the engine environment, so the thermal protection structure is required to ensure its safe work. At present, the multi-layer thermal protection structure with ceramic matrix composite (CMC) materials has gradually been applied as the internal resistant layer, due to its high specific strength and high temperature resistance. The mechanical-thermal coupling analysis method for CMC multi-layer thermal protection structures needs to be established, considering the complex distributed thermal and stress loads inside the combustion chambers. Firstly, for the local periodic unit of multilayer thermal protection structure, the mesoscale braided structure model and the homogenized model are constructed respectively, to explore the influence of the braided structure inside CMC layer on the temperature and stress distribution. Then, the macroscale model of the multi-layer CMC thermal protection structure is established, based on the feasibility of the local periodic element model verification method. The mechanical-thermal coupling analysis of the overall multi-layer thermal protection structure is carried out, and the temperature distribution and structural deformation are explored.
Research on the effect of fretting wear on the vibration characteristics of the tenon joint bladed disk
Authors: Qu Zhen , Yao Can , Zhu Honglai , Lin Xingrong , Chen Lei , Zhang Zhanhai , Fang Jie 
Published: March 2024

Abstract
The tenon joint structure is a typical structure of aero-engine bladed disk. Under external excitation, micro-slip inevitably occurs between the tenon and the tenon groove of the blade, which will cause fretting wear on the contact surface. The resonance frequency and margin of the bladed disk structure will change after fretting wear occurs. In this paper, a finite element subprogram is compiled based on the basic principle of Archard wear, which realizes the generation of surface wear morphology and multi-step iterative update of the double-tooth fir-tree joint model under fretting load. The subroutine is used to quantitatively analyze the wear depth distribution of the tenon joint surface under fretting loads. On this basis, the resonance margin and the vibration response characteristics of the bladed disk are quantitatively studied after fretting wear. The research results show that the natural vibration frequency of the bladed disk structure decreases at different wear times. This caused a decrease in the resonance margin of more than 80% of the measuring points. In addition, the resonance response amplitudes all showed an upward trend with the increase of wear depth.
Experimental study on multi-condition of axial flow pump in the whole flow field based on piv test
Authors: Zhu Hualun , Feng Chao , Wang Zonglong 
Published: March 2024

Abstract
To study the internal flow characteristics of the axial flow pump in the whole flow field under different flow conditions, particle image velocimetry technology was used to measure the steady and unsteady flow fields of the axial flow pump, analyzed the velocity field distribution at the impeller inlet, impeller inner, guide vane inner, and guide vane outlet of the pump under different flow conditions (Q/Q
des=0.8, 1, 1.1). Through the test and data analysis: under the three flow conditions, the velocity distribution trend of the impeller inlet of the axial flow pump is consistent and basically along the axis direction; there is a large velocity gradient in the flow field inside the impeller, and there is a significant acceleration near the hub trend, and there is a high-speed concentrated area; the velocity distribution trend in the guide vane is basically the same, and the fluid velocity changes more uniformly at the rated flow rate, and the flow tends to be more stable; a local high-speed area appears at the outer edge of the guide vane outlet, but in the second half The flow velocity in the pipeline is relatively uniform. The test results can provide a reference for the internal flow characteristics and performance optimization design of the axial flow pump.
Numerical study of jet-plate interaction and its effects on aeroacoustics
Authors: Wang Xindi , Lai Huanxin 
Published: March 2024

Abstract
In modern under-wing-mounted high-bypass engines, the exhausted jet from the engine will interact strongly with the wing and high-lift devices. In this paper, simulations of an isothermal jet flow at Mach number Ma = 0.5 and close to a flat plate are carried out using large-eddy simulation. Far-field acoustic results are obtained via the surface integral method of Ffowcs Williams and Hawkings (FW-H). The studied cases include an isolated jet and other three configurations with the jet and a plate spaced at the distance H/D
j = 1.0, 1.5, and 2.0, respectively, from the jet axis. Validation against experimental data is carried out. Far-field acoustic results show that the overall noise levels are significantly increased for the installed cases, particularly for polar angles in upstream of the nozzle. The noise levels are increased more as the plate approaches the jet axis, indicating the installation effect is related to the H/D and the polar angle. The pressure fluctuations are shown to decay along the radial direction. The mean flow and power spectral density of the axial velocity show the characteristics of the jet flow is not significantly changed by the presence of the plate.
Numerical study on aerodynamic performance and noise of protrusions structures near the trailing edge
Authors: Wang R , Xie J L 
Published: March 2024

Abstract
Based on the NACA0012 airfoil, different types of protrusions namely serrated protrusions and arc-shaped protrusions are set near the trailing edge. Both new airfoils have a certain decrease in flow performance however there is a significant reduction in aerodynamic noise of airfoils. This is because the protrusions damage the vortex near the trailing edge. In addition, the noise reduction of serrated protrusions is more significant than t of arc-shaped protrusions, about 2.7dB.
PIV measurement of cavitating flow around a pitching hydrofoil
Authors: Zhang Mengjie , Chen Jie , Xu Zhongyi , Ruan Xinjian , Huang Biao 
Published: March 2024

Abstract
Particle Image Velocimetry (PIV) and hydrodynamic measurements were applied to investigate the cavitating flow of a pitching hydrofoil in the form of triangular wave motion (mean incidence α
0=10°, amplitude Δα=5° and pitching frequency f*=2Hz). The Reynolds number is Re=4.5×105. The cavitation number is set to σ=2.3, 1.36. Different typical cavity patterns are observed by PIV images in the whole pitching period, including sub cavitation, inception cavitation, sheet cavitation and cloud cavitation. As the σ decreases, the cavity area increases. And the the corresponding time and position of cavitation patterns also changed significantly. In the instantaneous velocity field of an oscillating hydrofoil, the low velocity zone (LVZ) and the mainstream zone (MZ) are observed. The LVZ corresponds to the cavitation region and changes with the change of cavitation morphology. Meanwhile, the LVZ has a large velocity gradient. The velocity gradient in the MZ is larger along the direction parallel to the incoming flow, and the velocity tends to increase first and then decrease gradually downstream. With the decrease of cavitation number, the area of LVZ increases. And the distribution of LVZ is more uneven, which is mainly caused by oscillation motion and uneven water vapor mixing.
Application of three cavitation models in centrifugal pump cavitation flow simulation
Authors: Xie H , Luo X Q , Feng J J , Zhu G J , Li C H 
Published: March 2024

Abstract
In order to solve the problems of difficult and inaccurate cavitation simulation in centrifugal pumps, this paper adopts the commercial software CFX and realizes the same-platform comparison of Zwart-Gerber-Belamri model, Kunz model and Schner-Saer model in the simulation of centrifugal pumps’ cavitation by using its own language. The research results show that the Schner-Saer model can predict the external characteristics of the pump more accurately without considering the coefficient correction; By adjusting the empirical coefficients, different cavitation models can achieve the same effect; The Kunz model can predict the pressure distribution in the impeller more accurately, and the error is basically kept within 10% except for the local complex flow area; The change of the pump head is more obviously affected by the volume of the vapour in impeller, but weakly affected by the morphology of the vapour.
CFD verification of total pressure loss coefficient for gas-liquid two-phase flow
Authors: Kawahara T , Feng C N , Miyagawa K , Katayama Y 
Published: March 2024

Abstract
Traditionally, we design gas-liquid two-phase flow systems with pressure loss that is assumed by homogeneous flow. However, in real phenomena, the flow rate of water or air through a system cannot be correctly predicted unless we evaluate by the total pressure loss. there are currently few methods for measuring total pressure loss, and the value of total pressure loss is not yet clearly. Therefore, we devised a method to measure total pressure loss by pump Q-H characteristic and succeeded in measuring total pressure loss indirectly. We compared the test results with the analysis to clarify the prediction accuracy of the analysis using commercial codes. We apply three two-phase flow models for the simulation: a VOF model, a homogeneous flow model, and a two-fluid model. The simulation results of comparison between each fluid model indicated that the VOF model predicted with the best accuracy, with the error of 46% compared to the test results. This study provides a benchmark for the current commercial code, and the prediction accuracy of the different models provides a direction for future improvements in the analysis.
Synthesis and performance of a new long-acting slump retention agent at different temperatures
Authors: Lin Xiaochen 
Published: March 2024

Abstract
Under high-temperature conditions, the fluidity retention properties of polycarboxylate superplasticizers remain a challenge. This study improved the molecular structure of traditional slow-release polycarboxylate superplasticizers (also known as slump-retention agents) by introducing hydroxypropyl acrylate, successfully synthesizing a novel slump-retention agent that maintains concrete slump for an extended period at high temperatures. Comparing its performance with two other conventionally synthesized slump-retention agents, the superior performance of the new agent was verified. We then delved into the behavior of this novel slump-retention agent under different temperature conditions.