bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical study on heat transfer characteristics of swirling flow on dimpled surfaces with effusion holes at turbine blade leading edge
Authors: Kong Dehai , Liu Cunliang , Isaev S A 
Published: November 2021

Abstract
In this paper, we conducted a numerical study to investigate the effect of the offset of the jet holes on heat transfer of swirling flow in a concave target chamber with various dimple structures and effusion holes at the turbine blade leading edge. The distance of the jet holes off the centerline e/d varies from 0 to 2.0. Four types of dimple structure, including spherical dimples (SDs) and oval-trench dimples (OTDs) in the inline and staggered arrangement, are considered. The heat transfer performance of the different leading-edge, impingement-effusion cooling structures is evaluated and compared at a Reynolds number of 30,000 based on the jet hole diameter. Results show that the offset of the jet holes provides 15% higher overall heat transfer performance and more uniform heat transfer of the target surface within the e/d range of 0-2.0. The introduction of the dimple structures on the target surface slightly decreases the overall averaged Nusselt number but enhance the heat transfer quantity due to the clear increase of heat transfer areas. Under the same e/d, the OTD structure, especially with the staggered arrangement, is superior to SD structure.
Flow analysis in seamless hot-extruded pipes with helical inner ribbing surface
Authors: Kosmatskiy Ya Ig , Yu Egorov M , Lychakov V D 
Published: November 2021

Abstract
The article is devoted to numerical simulation of heat transfer processes occurring during the flow of a coolant in seamless hot-extrusion pipes with a spiral inner fin surface (TMK-IRS). A description of the numerical modeling technique is given along with the interface of the program used to create different types of internal fins. Thermohydraulic analysis of finned pipes for transient, turbulent and laminar flow regimes has been carried out. An estimate of the critical Reynolds number characterizing the transition to a turbulent regime, the nature of the transient flow regime in comparison with other classical cases is given.
Analysis of vortex structures formed in the winter in the atmosphere of Krasnoyarsk city
Authors: Filimonov S A , Meshkova V D , Dekterev A A , Gavrilov A A , Yu Litvintsev K , Shebelev A V 
Published: November 2021

Abstract
The article considers the influence of the relief, river, and urban development on the formation of vortex structures in the atmosphere and the spread of pollutants in the city of Krasnoyarsk in winter. The weak influence of urban development on the appearance of large vortex structures over the river is shown. However, in the ground layer, it significantly changes the flow pattern and determines the character of the distribution of pollutants.
Development of a simplified methodology for furnace aerodynamics with vortex combustion of organic fuel modeling
Authors: Prokhorov V B , Fomenko N E , Fomenko M V 
Published: November 2021

Abstract
This paper describes the process of developing a simplified methodology for furnace aerodynamics during the development or modernization of combustion schemes with direct-flow burners. This technique is based on the use of numerical modeling of air movement and turbulence phenomena in the furnace volume and allows for a relatively short period of time to analyze a large number of options for the burners and nozzles location. This is its advantage in comparison with the use of experimental modeling or numerical simulation with combustion when analyzing a variety of schemes. The model was developed on the basis of validated results of combustion processes numerical simulation in the K-50 boiler furnace. The paper presents the results of calculations performed for several variants of the simplified methodology. For further use, the option that best corresponds to full-scale studies taking into account the fuel combustion process has been selected. The main states of the methodology are formulated.
Experimental and computational study of a low-pressure natural circulation loop
Authors: Kabankov O N , Yagov V V , Zubov N O 
Published: November 2021

Abstract
The experimental and analytical study of single-phase flow and heat transfer in natural circulation loop has been carried out. Experiments were performed on water and ethanol that are the liquids with significantly different thermophysical properties. Experimental apparatus was a rectangular shaped loop with vertical flow up leg. The flow up and flow down legs of the loop are joined to the separator-condenser at the top of the loop. The upper limit of heat flux densities in the experiments was set with the consideration for flow regime to remain in single phase state along the whole heated length. Wall temperature time records being registered at different distances from the inlet to the heated zone indicate the occurrence of temperature fluctuations near the exit from heated zone even at relatively low heat flux densities. This fact displaces a complex changing of velocity profiles along the tube with vortex formation and occurrence of flow instability. Experimental data on longitudinal wall temperature distributions of heated section have been used to test a modified method of hydraulic calculation of the loop. It was pointed out that in spite of long year (since early 1950s) experimental, analytical and numerical investigations of natural circulation loops no suitable predicting recommendations for heat transfer and friction have been proposed till today for engineering hydraulic calculations of single-phase natural circulation loops.
Thermal detonation wave in liquid lead – water mixture
Authors: Kapustin A V , Melikhov V I , Melikhov O I , Saleh B , Finoshkina D V 
Published: November 2021

Abstract
It was developed the model of thermal detonation in a mixture of continuous liquid lead and dispersed steam/water particles. Stationary equations of mass, impulse and energy conservations laws for multiphase continuum are applied to describe internal structure of thermal detonation wave. They are supplemented by closing relations describing interfacial friction, heat transfer, and fragmentation. Conditions at leading shock wave and at Chapman-Jouguet plane are used as boundary conditions.
Influence of a non-condensable gas on mixing of a melt with water in a stratified configuration
Authors: Melikhov V I , Melikhov O I , Yakush S E , Saleh B , Borzdyi N A 
Published: November 2021

Abstract
The influence of bubbles of hot non-condensable gas formed at the interface between the melt and water on the formation of a mixture of melt with water capable of producing steam explosions is considered. The dynamics of such a bubble in subcooled water is analyzed numerically in a one-dimensional spherically symmetric approximation. It is shown that with significant initial superheat of the bubble relative to the water, a rapid drop in pressure in the bubble occurs due to strong heat removal into the water. This leads to the collapse of the bubble and the appearance of an accompanying flow of water. The results obtained made it possible to approximately describe the stage of collapse of the bubble as the polytropic process and to determine its index. The axisymmetric problem of the impact of the water jet on the surface of a melt during collapse of a gas bubble near the interface between the melt and water is numerically investigated. In this case, the obtained polytropic process equation is used to determine the pressure in the bubble. It is found that the resulting impact on the melt is capable of knocking out melt droplets into the water to a height of several centimeters, which leads to the formation of a layer of water mixed with the melt droplets, which is capable of producing strong steam explosions.
Heat flux during boiling of superfluid helium inside a porous body based on a two-fluid model
Authors: Puzina Yu Yu , Kryukov A P 
Published: November 2021

Abstract
The calculation of the recovery heat flux density is considered for superfluid helium boiling on the cylindrical heater inside porous structure. System of equations is based on the methods of continuum mechanics and molecular kinetic theory. The new type of boundary condition on the vapor-liquid interface based on the two-fluid model is formulated. Heat transfer in a free liquid is described by the Gorter-Mellink semi-empirical theory. Inside the porous structure the processes is discussed by the two-fluid model and filtration equation. Experimental data on the boiling of superfluid helium inside the porous structure are interpreted based on the formulated mathematical model. The qualitative and in some cases quantitative agreement between the calculated and experimental values of the recovery heat flux were obtained in the considered range of parameters
Numerical study of the vortex breakdown and vortex reconnection in the flow path of high-pressure water turbine
Authors: Sentyabov A V , Platonov D V , Minakov A V , Lobasov A S 
Published: November 2021

Abstract
The paper presents a study of the instability of the precessing vortex core in the model of the draft tube of a hydraulic turbine. The study was carried out using numerical modeling using various approaches: URANS, RSM, LES. The best agreement with the experimental data was shown by the RSM and LES methods with the modelling of the runner rotation by the sliding mesh method. In the regime under consideration, the precessing vortex rope is subject to instability, which leads to reconnection of its turns and the formation of an isolated vortex ring. Reconnection of the vortex core leads to aperiodic and intense pressure fluctuations recorded on the diffuser wall.
Heat transfer in laser passive and deformable mirrors
Authors: Leonov E , Chernykh A , Shanin Yu 
Published: November 2021

Abstract
In work, the possibilities of using uncooled and cooled optical elements (including laser passive and deformable mirrors) with an increase in the power of laser facilities are analyzed. To increase the permissible light loads acting on the optical elements, the use of highly efficient cooling systems with minichannels (coplanar and multi-tiered), providing a high compactness of the heat exchange surface and the intensification of heat transfer, is considered. The advantages and efficiency of the proposed cooling systems for reducing the displacement of the optical surface of the mirror due to bending are estimated.
The role of boundary conditions on the free surface of a liquid metal in an electrovortex flow
Authors: Teplyakov I O , Kiselyova S V , Malyshev K Yu , Mikhaylov E A 
Published: November 2021

Abstract
An electro-vortex flow between two hemispherical electrodes is considered. The influence of the type of boundary condition on the surface of a conducting liquid medium on the velocity field in the volume is studied numerically. The dependences of the velocity on the axis of the vessel on the radius of the small electrode and the parameter of the electric vortex flow are obtained for various types of boundary conditions on the surface.
The Phenomenon of Hysteresis in a Swirling Stream
Authors: Sergeev M N , Veretennikov S V , Pudeev A I 
Published: November 2021

Abstract
The article considers a swirling current with a sudden expansion. As a result of an experimental study, it was found that two flow modes can exist under these conditions. In the first case, there is an intense twist at the outlet of the vortex device, a zone of return currents and precessional oscillations. In the second case, there is no zone of return currents and precession. At the same time, the gas flow through the device increases abruptly
Influence of pulsed modes of a magnetic field on an electric vortex flow
Authors: Vinogradov D A , Teplyakov I O , Ivochkin Yu P , Shihov K A , Zhidkov A V 
Published: November 2021

Abstract
Using a fiber-optic velocity transducer, the effect of external pulsed magnetic fields on the structure of electrovortex flows is experimentally investigated. It is shown that an external pulsed magnetic field can lead to the appearance of oscillations of significant amplitude in a liquid metal.
A Predictive Model of Dimensional Deviation Based on Regeneration PSO-SVR with Cutting Feature Weight in Milling
Authors: Yao Hang , Luo Bin , Li Jing , Zhang Kaifu , Cao Zhiyue 
Published: November 2021

Abstract
Support vector regression (SVR) optimized by particle swarm optimization (PSO) has low predictive accuracy and premature convergence in milling. To solve this problem, A PSO-SVR model combined with the cutting feature weight was proposed in this paper. Firstly, basing on the SVR, the feature weight was integrated with the kernel function, and added the premature judging to the PSO to improve the global searching ability. Secondly, the mathematical model composed of the cutting force, temperature and cutting vibration was built based on the datasets obtained by experiment. The covariance was calculated to get the characteristic weights of process parameters, which promoted the incremental data in turn. Finally, the predictive model of the dimensional deviation was established based on the promoted PSO-SVR and the result was compared with the general PSO-SVR. The accuracy of the predictive model reached 97.5%. And compared with the predictive model of the general PSO-SVR without feature weighting, the dimensional deviation predictive accuracy and generalization ability of the regeneration PSO-SVR predictive model with feature weighting was improved by 37.75% and 24.5%.
Numerical Simulation Analysis of Flow and Heat Transfer in Medium Temperature Boiler
Authors: Sun Na , Yang Hexu 
Published: November 2021

Abstract
Waste heat recovery by waste heat boiler is one of the important means to utilize secondary energy, which is widely used in metallurgical industry. However, due to the great influence of production technology and other factors in industrial process, it brings many difficulties to waste heat utilization. Based on the structural parameters and operating parameters of the waste heat boiler, combined with the basic principles of fluid mechanics, the numerical calculation model of the waste heat boiler is established. The flow field and temperature field inside the waste heat boiler are studied and analyzed by numerical simulation method, which provides the necessary basis for its structural optimization.
A New Method of Manufacturing Hollow Shafts via Flexible Skew Rolling
Authors: Cao Xiaoqing , Wang Baoyu , Guo Wei , Ju Zhidong 
Published: November 2021

Abstract
The existing rolling process of large and long axle parts, such as the cross wedge rolling (CWR) process, requires special molds and larger equipment. Flexible skew rolling (FSR) hollow shafts with mandrel is a near net-shape rolling technology which can achieve the diversified production of rolled parts without special molds. It has significant advantages such as small equipment tonnage, small die size, low rolling load, simple process adjustment, and especially suitable for multi-variety and small-batch production. This paper proposes hollow train shafts formed by FSR with mandrel. Reasonable parameters were selected for experiments, and the forming process was calculated by finite element (FE) software. The experimental results are consistent with the simulation results, indicating that the FE model is reliable. The rolling force and rolling torque are analyzed by simulation. Finally, the microstructure of different positions of the rolled-piece is analyzed, and the microstructure of the rolled part is refined. It is provide a feasible scheme for the rolling of large hollow shaft parts.
Strategy and Technique of High Efficiency Balancing in Field for Turbo-Generator Units with Large Capacity
Authors: Cai Wenfang , Lu Songyuan , Wu Zhengfeng , Ying Guangyao , Wu Wenjian 
Published: November 2021

Abstract
Abstract.This paper aims at the high efficiency of field balancing for turbo-generator with large capacity currently, and introduces the strategies and key techniques of the rotor system balancing with practical cases of power plant in field. The acquisition, analysis and former processing of the original vibration data for balance calculation are included. Furthermore, they involve complete measuring points and conditions, accurate judgment for the types of unbalance exciting force and selection of stable vibration data, all these could reduce the blindness of balancing effectively. The strategies and techniques also contain the determination for axial plane of unbalance by the modal method, then the optimal steps and the plane of adding weight are chosen during the implementation of balancing. Besides, this paper also introduces the analysis and selection of influence coefficients and the phase of trial weight, these can help determine the final correction weight accurately in order to guarantee the balancing process prompt and efficient. Meanwhile, the restriction of practical location for adding weight and construction period of maintenance and production for the units should be considered during the high efficiency balancing in field. These strategies and techniques of high efficiency balancing have practical application value in promoting the technology of field balancing for turbo- generator units with large capacity.
Analysis on Leakage Characteristics of Labyrinth Piston Clearance in Reciprocating Labyrinth Compressor
Authors: Huang Rui , Cheng Junming , xia Tian , Feng Quanke 
Published: November 2021

Abstract
In this paper, the piston clearance leakage model in reciprocating labyrinth compressor is established, and the leakage characteristics of labyrinth piston are analysed. The results show that in the labyrinth entrance section, the gas velocity decreases greatly, and the throttling effect is the most obvious. In the middle section of the labyrinth, the flow velocity descending gradient decreases. In the exit section, the flow rate begins to increase. When the labyrinth clearance is less than or equal to 0.1 mm, the clearance changes has little effect on the leakage. When the clearance is greater than 0.1 mm, the leakage increases rapidly with the clearance increasing. When the piston operates eccentrically, the leakage will increase by 1.5 ∼ 2 times compared with the non-eccentric operation. Therefore, the eccentric operation of the piston should be avoided as much as possible and the clearance should be reduced.
The Analysis of a Generator Shaft Crack Cause by Torsional Vibration due to SSR
Authors: Cai Wenfang , Ying Guangyao , Li Weijun , Wang Zaihua 
Published: November 2021

Abstract
Abstract.This paper introduces the serious crack accident of the rotor of a 600 MW turbo-generator unit in Vietnam, which leads to the rotor scrapped. After excluding the material and design reasons, it is considered that the electrical torque is the possibility. Through the operation parameters and theoretical calculation of the unit, the fault reason is positioned as Sub-synchronous resonance. The most important criterion is that the vibration of Unit 1 increases simultaneously with that of Unit 2, which is physically isolated from Unit 1. Further theoretical calculation shows that the natural frequencies of torsional vibration are 13.74 Hz, 26.23 Hz and 30.30 Hz, which are complementary to the grid frequency at that time cause of the change of grid structure.
Reliability Analysis on Domestic Special CNC Machine Tools Based on Weibull Distribution
Authors: Shi Zhanghu , Zhao Xi , Zhang Huang , Sun Hailong , Zeng Chao , Lei Pei , He Xiaoxu , Xia Fengqin 
Published: November 2021

Abstract
Mean time between failures (MTBF), regarded as an important target to evaluate the performance of machine tool, is widely applied in analysis of reliability, especially in reliability model building. Taking Huazhong CNC HNC-848C Complex Machine Tool as research object, this paper conducted censored test to collect MTBF data during a period of 226 days. Based on the data and presupposed Weibull reliability model. Parameters of the model were estimated by least square method. Graph test Method and Kolmogorov-Smirnov Method are implemented to perform the hypothesis test on obtained parameters, which provides evaluation on MTBF of complex machine tool with theoretical basis and data reference.
Optimal Design of Brake Disc Structures for Brake Squeal Suppression
Authors: Pan Gongyu , Liu Zhikang , Xu Qizhao , Chen Lin 
Published: November 2021

Abstract
Aiming at the brake squeal problem of automobile disc brakes, an optimization design method of brake disc structure based on the weighted brake squeal tendency coefficient is proposed. This method is based on the brake squeal complex modal finite element model of a certain disc brake. Based on the validity of the model verified by the bench test, the single-sided disc surface height of the brake disc, the height of the radiating rib, the elastic modulus and the disc are selected. The four key structural parameters of the cap height are used as design variables. Taking the weighted braking squeal tendency coefficient proposed in this paper as the optimization target, the response surface method and the central composite test design are combined to construct a weighted braking squeal tendency coefficient response surface model, and use multi-island genetic algorithm to optimize the model. The results show that the optimization design method proposed in this paper can greatly improve the optimization efficiency while effectively reducing the screaming tendency of the disc brake in the full frequency band, so as to achieve the purpose of improving the NVH performance of the disc brake and improving the comfort of the car.
Numerical Simulation of Acoustic Scattering by a Cylinder Based on the Enhanced Optimized Scheme
Authors: Yuan Siqi , Ma Ruixuan , Wu Conghai , Zhang Shuhai 
Published: November 2021

AbstractThe enhanced optimized scheme we developed in the early work is employed to simulate the scattering of acoustic waves from a two-dimensional cylinder by solving the Euler equations. The numerical results of a benchmark problem are found to be in excellent agreement with the exact solution. Our numerical results show that when acoustic waves propagate through a cylinder, the acoustic scattering results in a spatial redistribution of the acoustic energy as well as an alteration of the phase of the waves. The directivities of the scattered fields change significantly for the different length ratios of acoustic wavelength to the radius of the cylinder.
Research on Intelligent Control and Integration Technology for Visual Inspection of TEC Components
Authors: Cai Zhishan , Chen Jiangwei , Yan Shaobin , Li Shizhan , Liao Tingdi 
Published: November 2021

Abstract
Technical schemes such as uniform TEC component feeding, posture adjustment, multi-station positioning, and communication between upper and lower machines were designed. The opto-electromechanical integration mechanism was integrated by software to realize the detection of TEC component surface defects, and qualified TEC components were separated from unqualified TEC components by blow sieving. Adopt ARM MCU for real-time control; Image recognition adopts the machine vision deep learning platform based on linux to learn and recognize the TEC components, and sends the results to the lower computer for sieving. The accuracy of triggering the camera to take pictures is 99.9%, which provides a guarantee for capturing and processing images accurately. The accuracy of blow sieving is over 99.9%, which can meet the sieving requirements. The electrical control system of the whole machine can meet the motion control requirements of detection.