scholarly journals Study on Lubrication Characteristics of Novel Forced Wave Generator of Harmonic Drive without Flexible Bearing

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 215
Author(s):  
Hongli Jia ◽  
Hongbing Xin
Keyword(s):  
The Novel ◽  
Harmonic Drive ◽  
Design And Optimization ◽  
Forced Wave ◽  
Gap Ratio ◽  
Optimal Value ◽  
Wave Generator ◽  
Computational Fluid Dynamics Cfd ◽  
Lubrication Characteristics ◽  
Cfd Method

In contrast to the conventional forced wave generator which consists of cam and flexible bearing in harmonic drive, the novel forced wave generator retains cam but cancels flexible bearing. In this article, the lubrication characteristics of the novel forced wave generator in harmonic drive is studied. First, an elliptical sliding bearing (ESB) model of simplified structure between the novel forced wave generator and the flex spline is established. Further, the computational fluid dynamics (CFD) method is employed to study the effect of some factors on the lubrication characteristics of the ESB model including elliptical gap ratio, width, and rotational speed. According to the analysis, the elliptical gap ratio has a great impact and its optimal value is 3, which is used in the design of the novel forced wave generator. Last, the practical design of the novel forced wave generator in harmonic drive is given, which can provide a basis for design and optimization of a forced wave generator without flexible bearing of the harmonic drive.

Optimization of a 17m Catamaran Based on the Resistance Performance

2013 ◽  
Vol 690-693 ◽  
pp. 3414-3418 ◽  
Author(s):  
Da Zheng Wang ◽  
Fei Ma ◽  
Lei Mei
Keyword(s):  
Wave Theory ◽  
Computational Method ◽  
Hydrodynamic Characteristics ◽  
Design And Optimization ◽  
Computational Fluid Dynamics Cfd ◽  
Design Speed ◽  
Cfd Method ◽  
Relationship Of ◽  
Resistance Performance ◽  
The Relationship

Based on Computational Fluid Dynamics (CFD) method and the wave theory, the analysis of hydrodynamic characteristics is made for a wave-piercing catamaran (WPC) in this paper. The resistances of the WPC with different demi-hull spacing are calculated by use of FLOW-3D, and the relationship of the wave resistance with the demi-hull spacing is also discussed. The comparison of results show that the computational resistance matches the test date well in the design speed. This computational method can predict the coefficient of WPC accurately and can be used as a guidance of WPC initional design and optimization on the demi-hull spacing.

scholarly journals Design of Novel Flash Ironmaking Reactors for Greatly Reduced Energy Consumption and CO2 Emissions

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 332
Author(s):  
Hong Yong Sohn ◽  
De-Qiu Fan ◽  
Amr Abdelghany
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Large Diameter ◽  
Reduction Reaction ◽  
The Novel ◽  
Height Ratio ◽  
Fine Iron ◽  
Computational Fluid Dynamics Cfd ◽  
High Reduction ◽  
Iron Ore Concentrate

The development of a novel ironmaking technology based on fine iron ore concentrate in a flash reactor is summarized. The design of potential industrial reactors for flash ironmaking based on the computational fluid dynamics technique is described. Overall, this simulation work has shown that the size of the reactor used in the novel flash ironmaking technology (FIT) can be quite reasonable vis-à-vis the blast furnaces. A flash reactor of 12 m diameter and 35 m height with a single burner operating at atmospheric pressure would produce 1.0 million tons of iron per year. The height can be further reduced by either using multiple burners, preheating the feed gas, or both. The computational fluid dynamics (CFD)-based design of potential industrial reactors for flash ironmaking pointed to a number of features that should be incorporated. The flow field should be designed in such a way that a larger portion of the reactor is used for the reduction reaction but at the same time excessive collision of particles with the wall must be avoided. Further, a large diameter-to-height ratio that still allows a high reduction degree should be used from the viewpoint of decreased heat loss. This may require the incorporation of multiple burners and solid feeding ports.

Effect of recess depth on lubrication performance of annular recess hydrostatic thrust bearing by constant rate flow

2018 ◽  
Vol 70 (1) ◽  
pp. 68-75 ◽  
Author(s):  
Jun-peng Shao ◽  
Guang-dong Liu ◽  
Xiao-dong Yu ◽  
Yan-qin Zhang ◽  
Xiu-li Meng ◽  
...  
Keyword(s):  
Thrust Bearing ◽  
Simulation Method ◽  
Content Type ◽  
Oil Film ◽  
Constant Rate ◽  
Lubrication Performance ◽  
Optimal Value ◽  
Improved Performance ◽  
Lubrication Characteristics ◽  
Volume Method

Purpose The purpose of this paper is to describe a simulation and experimental research concerning the effect of recess depth on the lubrication performance of a hydrostatic thrust bearing by constant rate flow. Design/methodology/approach The computational fluid dynamics and finite volume method have been used to compute the lubrication characteristics of an annular recess hydrostatic thrust bearing with different recess depths. The performances are oil recess pressure, oil recess temperature and oil film velocity. The recess depth has been optimized. A test rig is established for testing the pressure field of the structure of hydrostatic thrust bearing after recess depth optimization, and experimental results show that experimental data are basically identical with the simulation results, which demonstrates the validity of the proposed numerical simulation method. Findings The results demonstrate that the oil film temperature decreases and the oil film pressure first increases and then decreases with an increase in the recess depth, but oil film velocity is constant. To sum up comprehensive lubrication performance, the recess depth of 3.5 mm is its optimal value for the annular recess hydrostatic thrust bearing. Originality/value The computed results indicate that to get an improved performance from a constant flow hydrostatic thrust bearing, a proper selection of the recess depth is essential.

An anti-crystallization design of selective catalytic reduction nozzle holder

2021 ◽  
pp. 095440702097084
Author(s):  
Dewen Liu ◽  
Kai Lu ◽  
Shusen Liu ◽  
Yan Wu ◽  
Shuzhan Bai
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Injection System ◽  
Test Results ◽  
Verification Methods ◽  
Crystallization Risk ◽  
Protective Cover ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Good Agreement

From the aspect of reducing the risk of crystallization on nozzle surface, a new design of nozzle protective cover was to solve the problem in selective catalytic reduction (SCR) urea injection system. The simulation calculation and experimental verification methods were used to compare different schemes. The results show that reducing the height of nozzle holder can reduce the vortex currents near nozzle surface and effectively reduce the risk of crystallization on the nozzle surface. It is proposed to install a protective cover in the nozzle holder under the scheme of reducing the height of nozzle holder, which can further eliminate the vortex. Simulation and test results demonstrate good agreement under the rated running condition. The scheme of adding a protective cover in the nozzle holder shows the least crystallization risk by computational fluid dynamics (CFD) method. The crystallization cycle test shows that, after the height of nozzle holder is reduced, the risk of crystallization on the nozzle surface is reduced correspondingly. The addition of a protective cover in the nozzle holder solves the problem of crystallization on the nozzle surface, which provides a new method for anti-crystallization design.

scholarly journals Validasi Model Turbulensi pada Simulasi Numerik Menggunakan Software Fluent dengan Sayap Onera M6

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Sulistiya Sulistiya ◽  
Alief Sadlie Kasman
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Computational Result ◽  
Computational Simulation ◽  
Turbulence Models ◽  
Wind Tunnels ◽  
Direct Testing ◽  
The World ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

AbstractNumerical simulation using Computational Fluid Dynamics (CFD) method is one way of predicting airflow characteristics on the model. This method is widely used because it is relatively inexpensive and faster in getting desired results compared with performing direct testing. The correctness of a computational simulation output is highly dependent on the input and how it was processed. In this paper, simulation is done on Onera M6 Wing, to investigate the effect of a turbulence model’s application on the accuracy of the computational result. The choice of Onera M6 Wing as a simulation’s model is due to its extensive database of testing results from various wind tunnels in the world. Among Turbulence models used are Spalart-Allmaras, K-Epsilon, K-Omega, and SST.Keywords: CFD, fluent, Model, Turbulence, Onera M6, Spalart-Allmaras, K-Epsilon, K-Omega, SST.AbstraksSimulasi numerik dengan menggunakan metode Computational Fluid Dynamics (CFD) merupakan salah satu cara untuk memprediksi karakteristik suatu aliran udara yang terjadi pada model. Metode ini banyak digunakan karena sifatnya yang relatif murah dan cepat untuk mendapatkan hasil dibandingkan dengan melakukan pengujian langsung. Benar tidak hasil sebuah simulasi komputasi sangat tergantung pada inputan yang diberikan serta cara memproses data inputan tersebut. Pada tulisan ini dilakukan simulasi dengan menggunakan sayap onera M6 dengan tujuan untuk mengetahui pengaruh penggunaan model turbulensi terhadap keakuratan hasil komputasi. Pilihan sayap onera M6 sebagai model simulasi dikarenakan model tersebut sudah memiliki database hasil pengujian yang cukup lengkap dan sudah divalidasi dari berbagai terowongan angin di dunia. Model turbulensi yang digunakan diantaranya Spalart-Allmaras, K-Epsilon, K-Omega dan SST.Kata Kunci : CFD, fluent, Model, Turbulensi, Onera M6, Spalart-Allmaras, K-Epsilon, K-Omega, SST.

scholarly journals Study on Flow Boiling Characteristics in Rectangle Channel After Formation of Blisters

2021 ◽  
Vol 9 ◽  
Author(s):  
Huijian Huang ◽  
Chong Chen ◽  
Luguo Liu ◽  
Yu Liu ◽  
Linfeng Li ◽  
...  
Keyword(s):  
Flow Boiling ◽  
The Novel ◽  
Local Flow ◽  
Flow Through ◽  
Cfd Method ◽  
Dry Out ◽  
Fuel Elements ◽  
Type Fuel ◽  
Plate Type ◽  
Structure Choice

Plate-type fuel elements is one of the first fuel structure choice for the novel integrated PWR, however, blisters will appear on the cladding induced by irradiation and fission. In this work CFD method was used to investigate the subcooled boiling characteristic of the water in rectangle channel with round and pillow blisters, the modified RPI model was also proposed, we can draw conclusions as follows: In the channel with round blister, as the blisters will increase the local flow resistance and more fluid will flow through center of the channel. Boiling occurred only in the area near the edges, nearly no vapor appeared at the center of the channel. The boiling region in channel with pillow shape blisters is wider and concentrated between two pillow blisters and downstream of the non-blisters side. The dry out area are both in the downstream region of blisters for the two types of channels.

scholarly journals Flutter speed prediction by using deep learning

2021 ◽  
Vol 13 (11) ◽  
pp. 168781402110622
Author(s):  
Yi-Ren Wang ◽  
Yi-Jyun Wang
Keyword(s):  
Neural Network ◽  
Deep Learning ◽  
Short Term Memory ◽  
Learning Technology ◽  
Memory Space ◽  
Flutter Speed ◽  
Aeroelastic Flutter ◽  
Speed Prediction ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

Deep learning technology has been widely used in various field in recent years. This study intends to use deep learning algorithms to analyze the aeroelastic phenomenon and compare the differences between Deep Neural Network (DNN) and Long Short-term Memory (LSTM) applied on the flutter speed prediction. In this present work, DNN and LSTM are used to address complex aeroelastic systems by superimposing multi-layer Artificial Neural Network. Under such an architecture, the neurons in neural network can extract features from various flight data. Instead of time-consuming high-fidelity computational fluid dynamics (CFD) method, this study uses the K method to build the aeroelastic flutter speed big data for different flight conditions. The flutter speeds for various flight conditions are predicted by the deep learning methods and verified by the K method. The detailed physical meaning of aerodynamics and aeroelasticity of the prediction results are studied. The LSTM model has a cyclic architecture, which enables it to store information and update it with the latest information at the same time. Although the training of the model is more time-consuming than DNN, this method can increase the memory space. The results of this work show that the LSTM model established in this study can provide more accurate flutter speed prediction than the DNN algorithm.

CFD Analysis of a Water Flume Design for Testing Marine and Hydrokinetics Energy Converters

2018 ◽  
Author(s):  
Akshith Subramanian ◽  
Navid Goudarzi
Keyword(s):  
Test Section ◽  
Lower Cost ◽  
Performance Metrics ◽  
Experimental Testing ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Design Parameters ◽  
Energy Technologies ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

Marine and hydrokinetic (MHK) energy resources with advantages such as predictability and less variability compared to other forms of renewable energies, have been drawing more interest in recent years. One important phase before commercialization of new MHK technologies is to conduct experimental testing and evaluate their performance in a real environment. In this work, a numerical computational fluid dynamics (CFD) method is used to study the fluid flow behavior within a designed water flume for MHK energy technologies. The water flume design parameters were given by the team collaborators at National Renewable Energy Laboratory (NREL) and Colorado School of Mines. The results from this simulation showed the flow characteristics within the test-section of the proposed water flume design. These results can be used for the follow on phases of this research that includes testing scaled MHK prototypes at different flow rates as well as optimizing either the water flume design to obtain more realistic flow characteristics within the test section or the MHK devices to obtain higher performance metrics at lower cost.

Natural Ventilation Design and Optimization of Large-Scale Industrial Workshop

2014 ◽  
Vol 1065-1069 ◽  
pp. 2137-2140
Author(s):  
Xiao Hu Yang ◽  
Yan Long ◽  
Ling Zhao Meng ◽  
Yu Hui Jin
Keyword(s):  
Large Scale ◽  
Natural Ventilation ◽  
Thermal Environment ◽  
Orthogonal Experiment ◽  
Structure Design ◽  
Iron And Steel ◽  
Design And Optimization ◽  
Experiment Method ◽  
Orthogonal Experiment Method ◽  
Computational Fluid Dynamics Cfd

In this paper, we used orthogonal experiment method and Computational Fluid Dynamics (CFD) technology to simulate the thermal environment of the iron and steel workshop. By comparing and analyzing the temperature distribution and air flow of workshops with different window structures, we obtained an optimization of natural ventilation design for industrial workshop. The research results can be used for the structure design or reformation of industrial workshops as reference.

scholarly journals A Coupled, Semi-Numerical Model for Thermal Analysis of Medium Frequency Transformer

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 328 ◽  
Author(s):  
Haonan Tian ◽  
Zhongbao Wei ◽  
Sriram Vaisambhayana ◽  
Madasamy Thevar ◽  
Anshuman Tripathi ◽  
...  
Keyword(s):  
Numerical Model ◽  
Analytical Model ◽  
Electromagnetic Analysis ◽  
Medium Frequency ◽  
Fluid Analysis ◽  
Fluid Behavior ◽  
Proposed Model ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Thermal Fluid Analysis

Medium-frequency (MF) transformer has gained much popularity in power conversion systems. Temperature control is a paramount concern, as the unexpected high temperature declines the safety and life expectancy of transformer. The scrutiny of losses and thermal-fluid behavior are thereby critical for the design of MF transformers. This paper proposes a coupled, semi-numerical model for electromagnetic and thermal-fluid analysis of MF oil natural air natural (ONAN) transformer. An analytical model that is based on spatial distribution of flux density and AC factor is exploited to calculate the system losses, while the thermal-hydraulic behavior is modelled numerically leveraging the computational fluid dynamics (CFD) method. A close-loop iterative framework is formulated by coupling the analytical model-based electromagnetic analysis and CFD-based thermal-fluid analysis to address the temperature dependence. Experiments are performed on two transformer prototypes with different conductor types and physical geometries for validation purpose. Results suggest that the proposed model can accurately model the AC effects, losses, and the temperature rises at different system components. The proposed model is computationally more efficient than the full numerical method but it reserves accurate thermal-hydraulic characterization, thus it is promising for engineering utilization.

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