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Article
Publication date: 16 June 2020

Taurista Perdana Syawitri, Yufeng Yao, Jun Yao and Budi Chandra

The aim of this paper is to assess the ability of a stress-blended eddy simulation (SBES) turbulence model to predict the performance of a three-straight-bladed vertical axis wind…

291

Abstract

Purpose

The aim of this paper is to assess the ability of a stress-blended eddy simulation (SBES) turbulence model to predict the performance of a three-straight-bladed vertical axis wind turbine (VAWT). The grid sensitivity study is conducted to evaluate the simulation accuracy.

Design/methodology/approach

The unsteady Reynolds-averaged Navier–Stokes equations are solved using the computational fluid dynamics (CFD) technique. Two types of grid topology around the blades, namely, O-grid (OG) and C-grid (CG) types, are considered for grid sensitivity studies.

Findings

With regard to the power coefficient (Cp), simulation results have shown significant improvements of predictions using compared to other turbulence models such as the k-e model. The Cp distributions predicted by applying the CG mesh are in good agreement with the experimental data than that by the OG mesh.

Research limitations/implications

The current study provides some new insights of the use of SBES turbulence model in VAWT CFD simulations.

Practical implications

The SBES turbulence model can significantly improve the numerical accuracy on predicting the VAWT performance at a lower tip speed ratio (TSR), which other turbulence models cannot achieve. Furthermore, it has less computational demand for the finer grid resolution used in the RANS-Large Eddy Simulation (LES) “transition” zone compared to other hybrid RANS-LES models.

Originality/value

To authors’ knowledge, this is the first attempt to apply SBES turbulence model to predict VAWT performance resulting for accurate CFD results. The better prediction can increase the credibility of computational evaluation of a new or an improved configuration of VAWT.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 2
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 8 May 2018

Chawki Abdessemed, Yufeng Yao, Abdessalem Bouferrouk and Pritesh Narayan

The purpose of this paper is to use dynamic meshing to perform CFD analyses of a NACA 0012 airfoil fitted with a morphing trailing edge (TE) flap when it undergoes static and…

867

Abstract

Purpose

The purpose of this paper is to use dynamic meshing to perform CFD analyses of a NACA 0012 airfoil fitted with a morphing trailing edge (TE) flap when it undergoes static and time-dependent morphing. The steady CFD predictions of the original and morphing airfoils are validated against published data. The study also investigates an airfoil with a hinged TE flap for aerodynamic performance comparison. The study further extends to an unsteady CFD analysis of a dynamically morphing TE flap for proof-of-concept and also to realise its potential for future applications.

Design/methodology/approach

An existing parametrization method was modified and implemented in a user-defined function (UDF) to perform dynamic meshing which is essential for morphing airfoil unsteady simulations. The results from the deformed mesh were verified to ensure the validity of the adopted mesh deformation method. ANSYS Fluent software was used to perform steady and unsteady analysis and the results were compared with computational predictions.

Findings

Steady computational results are in good agreement with those from OpenFOAM for a non-morphing airfoil and for a morphed airfoil with a maximum TE deflection equal to 5 per cent of the chord. The results obtained by ANSYS Fluent show that an average of 6.5 per cent increase in lift-to-drag ratio is achieved, compared with a hinged flap airfoil with the same TE deflection. By using dynamic meshing, unsteady transient simulations reveal that the local flow field is influenced by the morphing motion.

Originality/value

An airfoil parametrisation method was modified to introduce time-dependent morphing and used to drive dynamic meshing through an in-house-developed UDF. The morphed airfoil’s superior aerodynamic performance was demonstrated in comparison with traditional hinged TE flap. A methodology was developed to perform unsteady transient analysis of a morphing airfoil at high angles of attack beyond stall and to compare with published data. Unsteady predictions have shown signs of rich flow features, paving the way for further research into the effects of a dynamic flap on the flow physics.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 28 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 22 May 2007

Deepthi Duddempudi, Yufeng Yao, David Edmondson, Jun Yao and Andy Curley

The paper seeks to perform a detailed numerical study of flow over a generic fan‐wing airfoil and also attempts to modify the geometry for the improvement of the aerodynamic…

2143

Abstract

Purpose

The paper seeks to perform a detailed numerical study of flow over a generic fan‐wing airfoil and also attempts to modify the geometry for the improvement of the aerodynamic performance.

Design/methodology/approach

Advanced computational fluid dynamics (CFD) technique has been employed for evaluation of the aerodynamic performance (e.g. lift/drag ratio) of a model problem. Numerical investigation starts with sensitivity studies to minimize domain size influence and grid dependency, followed by time‐accurate transient calculations. A preliminary re‐design exercise has been performed by analyzing the results of a current design.

Findings

CFD predicted lift force agrees fairly well with the measurement data with about 6.55 per cent error, while drag force compares less favourably with about 12.59 per cent error. Both errors are generally acceptable for an engineering application of complex flow problems. Several key flow features observed previously by experiment have also been re‐produced by simulation, notably the eccentric vortex motions in the blade interior and the stream “jet” flow outside the blades near the exit. With the modified geometry, there is a considerable lift/drag ratio improvement of about 29.42 per cent. The possible reasons for such a significant improvement have been discussed.

Research limitations/implications

As it is the first step towards the detailed flow analysis of this type of model, a simpler blade shape rather than “real” one has been used.

Practical implications

The paper provides a very useful source of information and could be used as guidance for further industry practice of unmanned aerial vehicles design.

Originality/value

This paper is valuable for both academic researchers and industry engineers, especially those working in the area of high‐lift wing design. The works presented are original.

Details

Aircraft Engineering and Aerospace Technology, vol. 79 no. 3
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 10 July 2017

Chaoran Liu, Yufeng Su, Jinzhao Yue, Junjie Wang, Weiwei Xia, Dongxue Li, Wen Wang, Pan Wang and Zhiyong Duan

A self-adaptive piston is designed for the compressional gas cushion press nanoimprint lithography system. It avoids the lube pollution and high wear of traditional piston.

89

Abstract

Purpose

A self-adaptive piston is designed for the compressional gas cushion press nanoimprint lithography system. It avoids the lube pollution and high wear of traditional piston.

Design/methodology/approach

The self-adaptive piston device consists of symmetrical piston bodies, piston rings and other parts. The two piston bodies are linked by a ball-screw. The locking nut adjusts the distance between two piston bodies to avoid the piston rings from being stuck. The piston rings are placed between two piston bodies.

Findings

The simulation results based on COMSOL indicate that cylinder vibration caused by self-adaptive piston is 15.9 times smaller than the one caused by a traditional piston.

Originality/value

The self-adaptive piston is superior to the traditional piston in decreasing cylinder vibration.

Details

Industrial Lubrication and Tribology, vol. 69 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 6 August 2019

Yannapol Sriphutkiat and Yufeng Zhou

The capability of microparticle/objects patterning in the three-dimensional (3D) printing structure could improve its performance and functionalities. This paper aims to propose…

327

Abstract

Purpose

The capability of microparticle/objects patterning in the three-dimensional (3D) printing structure could improve its performance and functionalities. This paper aims to propose and evaluate a novel acoustic manipulation approach.

Design/methodology/approach

A novel method to accumulate the microparticles in the cylindrical tube during the 3D printing process is proposed by acoustically exciting the structural vibration of the cylindrical tube at a specific frequency, and subsequently, focusing the 50-μm polystyrene microparticles at the produced pressure node toward the center of the tube by the acoustic radiation force. To realize this solution, a piezoceramic plate was glued to the outside wall of a cylindrical glass tube with a tapered nozzle. The accumulation of microparticles in the tube and printing structure was monitored microscopically and the accumulation time and width were quantitatively evaluated. Furthermore, the application of such technology was also evaluated in the L929 and PC-12 cells suspended in the sodium alginate and gelatin methacryloyl.

Findings

The measured location of pressure and the excitation frequency of the cylindrical glass tube (172 kHz) agreed quite well with our numerical simulation (168 kHz). Acoustic excitation could effectively and consistently accumulate the microparticles. It is found that the accumulation time and width of microparticles in the tube increase with the concentration of sodium alginate and microparticles in the ink. As a result, the microparticles are concentrated mostly in the central part of the printing structure. In comparison to the conventional printing strategy, acoustic excitation could significantly reduce the width of accumulated microparticles in the printing structure (p < 0.05). In addition, the possibility of high harmonics (385 and 657 kHz) was also explored. L929 and PC-12 cells suspended in the hydrogel can also be accumulated successfully.

Originality/value

This paper proves that the proposed acoustic approach is able to increase the accuracy of printing capability at a low cost, easy configuration and low power output.

Details

Rapid Prototyping Journal, vol. 25 no. 5
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 25 October 2018

Yufeng SU, Nengquan WU and Xiang Zhou

Entrepreneurial process strongly relies on context. The previous entrepreneurship research in developed countries over-emphasizes on its economic impact, but ignores its social…

800

Abstract

Purpose

Entrepreneurial process strongly relies on context. The previous entrepreneurship research in developed countries over-emphasizes on its economic impact, but ignores its social impact, which leads to the slow development of entrepreneurship theories. Transitioning China provides entrepreneurs with a typical environment where opportunities and constraints coexist, which is a new research area in the field of entrepreneurship study.

Design/methodology/approach

Based on the grounded theory approach, this paper generalizes a local entrepreneurial process model from a multiple case study.

Findings

The paper states that the interaction among entrepreneurs, opportunities and institutional context is the core of the process. To be specific, entrepreneurial process includes an inner and an outer mechanism. The inner mechanism is based on the relations among institutional constraints, entrepreneurs and opportunities: nascent entrepreneurs, forced by institutional constraints to start a business, undergo a psychological process with entrepreneurial angst, reflective learning and effectuation and finally create business opportunities. The outer mechanism is grounded in the relations among new ventures, institutional evolution and opportunity development: new ventures facilitate institutional evolution through institutional entrepreneurship strategies, which in turn supports the ventures in the sustainable development of opportunities.

Originality/value

This study illuminates the social and institutional impact of entrepreneurial behavior, which is gradually fading and forgotten in modern society. The findings of the study enrich the research on entrepreneurial process, entrepreneurial cognition and institutional entrepreneurship and also provide implications for entrepreneurs.

Details

Nankai Business Review International, vol. 10 no. 2
Type: Research Article
ISSN: 2040-8749

Keywords

Available. Content available
Article
Publication date: 30 September 2014

10

Abstract

Details

Journal of Manufacturing Technology Management, vol. 25 no. 8
Type: Research Article
ISSN: 1741-038X

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Book part
Publication date: 29 May 2012

Pan Haixiao

Purpose – To review the place of bicycle transportation within the Chinese national objective of sustainable development.Methodology – The chapter provides an analysis of the…

Abstract

Purpose – To review the place of bicycle transportation within the Chinese national objective of sustainable development.

Methodology – The chapter provides an analysis of the evolution of bicycle transportation policies in China, and a discussion of the latest developments in the function and operation of public bicycle hire schemes.

Findings – Due to high population density, the prevailing mix of land use and a lack of affordability of cars and motor scooters, bicycle transportation has historically been very common in the urban areas of China. However, since the 1990s, many Chinese cities implemented restrictive policies on the development of bicycle transportation and the modal share of bicycles has reduced sharply.

Practical implications – The chapter suggests that China would need to create favourable conditions for bicycle transportation in urban areas through means such as policy support, land use planning, use of economic levers and through creating an acceptable social and cultural atmosphere for cycling. Finally, the maintenance of a relatively high proportion of bicycle traffic would need to be regarded as an index for sustainable urban development.

Details

Cycling and Sustainability
Type: Book
ISBN: 978-1-78052-299-9

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Article
Publication date: 11 March 2014

Yufeng Qu and Guanghua Zong

This paper aims to introduce a compact and low-cost robotized system and corresponding processing method for automatically identifying and de-stacking circulation boxes under…

303

Abstract

Purpose

This paper aims to introduce a compact and low-cost robotized system and corresponding processing method for automatically identifying and de-stacking circulation boxes under natural stacking status.

Design/methodology/approach

The whole system is composed of an industrial robot, a laser scanner and a computer. Automated de-stacking requires comprehensive and accurate status information of each box. To achieve this goal, the robot carries the laser scanner to perform linear scanning to describe a full depth image for the whole working area. Gaussian filter is applied to the image histogram to suppress the undesired noise. Draining and flooding process derived from classic algorithm identifies each box region from an intensity image. After parameters calculation and calibration, the grasping strategy is estimated and transferred to the robot to finish the de-stacking task.

Findings

Currently, without pre-defined stack status, there is still manual operated alignment in stacking process in order to enable automatic de-stacking using robot. Complicated multi-sensor system such as video cameras can recognize the stack status but also brings high-cost and poor adaptability. It is meaningful to research on the efficient and low-cost measurement system as well as corresponding common data processing method.

Research limitations/implications

This research presents an efficient solution to automated de-stacking task and only tests for three columns stack depending on the actual working condition. It still needs to be developed and tested for more situations.

Originality/value

Utilizing only single laser scanner to measure box status instead of multi-sensor is novel and identification method in research can be suitable for different box types and sizes.

Details

Industrial Robot: An International Journal, vol. 41 no. 2
Type: Research Article
ISSN: 0143-991X

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Article
Publication date: 29 April 2021

Yuan-pei Kuang, Jia-li Yang and Meseret-Chanie Abate

The multidimensional effects of farmland transfer in China have been profoundly unstudied. The purpose of this paper is to provide insights on the effects of the intermediary role…

554

Abstract

Purpose

The multidimensional effects of farmland transfer in China have been profoundly unstudied. The purpose of this paper is to provide insights on the effects of the intermediary role of agricultural total factor productivity (TFP) of farmland transfer on agricultural economic growth in China.

Design/methodology/approach

Based on the agricultural data of 30 provinces in China over the period 2005–2018, this paper uses the intermediary effect model to test the relationship between farmland transfer, agricultural TFP and agricultural economic growth. This paper employed an intermediary effect test model to investigate the intermediary role of agricultural TFP in the influence of farmland transfer on agricultural economic growth.

Findings

The findings indicated that farmland transfer has a significant effect on promoting agricultural economic growth. There is a significant “inverted U-shaped” relationship between farmland transfer and agricultural TFP. The sample value of 84.3% of farmland transfers in China is still within the TFP promoting effect range. In addition, farmland transfer has an indirect impact on agricultural economic growth through the channel of agricultural TFP. Agricultural TFP plays a significant intermediary role, but the effect is relatively low

Originality/value

This paper is the first to provide fundamental evidence on the impact of farmland transfers on agricultural economic growth in China, driven by agricultural TFP as an intermediary factor. Agricultural TFP can reduce the involution effect of farmland transfer and promote an indirect effect on agricultural economic growth.

Details

China Agricultural Economic Review, vol. 14 no. 1
Type: Research Article
ISSN: 1756-137X

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