Rapid computation of rotary derivatives for subsonic and low transonic flows

2019 ◽  
Vol 36 (9) ◽  
pp. 3108-3121
Author(s):  
Jian-Ming Fu ◽  
Hai-Min Tang ◽  
Hong-Quan Chen
Keyword(s):  
Mach Number ◽  
Normal Velocity ◽  
New Approach ◽  
Content Type ◽  
Strip Theory ◽  
Model Aircraft ◽  
Computational Fluid Dynamics Cfd ◽  
Steady Solutions ◽  
State Pressure ◽  
Derivatives Of

Purpose The purpose of this paper is to develop a new approach for rapid computation of subsonic and low-transonic rotary derivatives with the available steady solutions obtained by Euler computational fluid dynamics (CFD) codes. Design/methodology/approach The approach is achieved by the perturbation on the steady-state pressure of Euler CFD codes. The resulting perturbation relation is established at a reference Mach number between rotary derivatives and normal velocity on surface due to angular velocity. The solution of the reference Mach number is generated technically by Prandtl–Glauert compressibility correction based on any Mach number of interest under the assumption of simple strip theory. Rotary derivatives of any Mach number of interest are then inversely predicted by the Prandtl–Glauert rule based on the reference Mach number aforementioned. Findings The resulting method has been verified for three typical different cases of the Basic Finner Reference Projectile, the Standard Dynamics Model Aircraft and the Orion Crew Module. In comparison with the original perturbation method, the performance at subsonic and low-transonic Mach numbers has significantly improved with satisfactory accuracy for most design efforts. Originality/value The approach presented is verified to be an efficient way for computation of subsonic and low-transonic rotary derivatives, which are performed almost at the same time as an accounting solution of steady Euler equations.

Computational fluid dynamics analysis of the effect of throat diameter on the fluid flow and performance of ejector

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammadreza Salehi ◽  
Nader Pourmahmoud ◽  
Amir Hassanzadeh ◽  
S. Hoseinzadeh ◽  
P.S. Heyns
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mach Number ◽  
Content Type ◽  
Standard Code ◽  
Computational Fluid Dynamics Analysis ◽  
Fluent Software ◽  
Computational Fluid Dynamics Cfd ◽  
Throat Diameter ◽  
And Performance

Purpose Using the computational fluid dynamics (CFD) technique, this paper aims to investigate the influence of key parameters such as throat diameter; the suction ratio on the flow field behaviors such as Mach number; pressure; and temperature. Design/methodology/approach To investigate the effect of throat diameter, it is simulated for 4, 6, 8 and 10 mm as throat diameters. The governing equations have been solved by standard code of Fluent Software together with a compressible 2 D symmetric and turbulence model with the standard k–ε model. First, the influence of the throat diameter is investigated by keeping the inlet mass flow constant. Findings The results show that a place of shock wave creation is changed by changing the throat diameter. The obtained results illustrate that the maximum amount of Mach number is dependent on the throat diameter. It is obtained from the results that for smaller throats higher Mach numbers can be obtained. Therefore, for mixing purposes smaller throats and for exhausting bigger throats seems to be appropriate. Originality/value The obtained numerical results are compared to the existing experimental ones which show good agreement.

Yaw Galloping of a TLWP Platform Under High Speed Currents by Analytical Methods and its Comparison With Experimental Results

2017 ◽  
Author(s):  
Francisco Lamas ◽  
Miguel A. M. Ramirez ◽  
Antonio Carlos Fernandes
Keyword(s):  
High Speed ◽  
Production Systems ◽  
Experimental Tests ◽  
Experimental Results ◽  
Analytical Methodology ◽  
New Approach ◽  
Laboratory Facilities ◽  
Polynomial Curve ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Analyses

Flow Induced Motions are always an important subject during both design and operational phases of an offshore platform life. These motions could significantly affect the performance of the platform, including its mooring and oil production systems. These kind of analyses are performed using basically two different approaches: experimental tests with reduced models and, more recently, with Computational Fluid Dynamics (CFD) dynamic analysis. The main objective of this work is to present a new approach, based on an analytical methodology using static CFD analyses to estimate the response on yaw motions of a Tension Leg Wellhead Platform on one of the several types of motions that can be classified as flow-induced motions, known as galloping. The first step is to review the equations that govern the yaw motions of an ocean platform when subjected to currents from different angles of attack. The yaw moment coefficients will be obtained using CFD steady-state analysis, on which the yaw moments will be calculated for several angles of attack, placed around the central angle where the analysis is being carried out. Having the force coefficients plotted against the angle values, we can adjust a polynomial curve around each analysis point in order to evaluate the amplitude of the yaw motion using a limit cycle approach. Other properties of the system which are flow-dependent, such as damping and added mass, will also be estimated using CFD. The last part of this work consists in comparing the analytical results with experimental results obtained at the LOC/COPPE-UFRJ laboratory facilities.

scholarly journals The concept of neutrality: a new approach

2019 ◽  
Vol 76 (1) ◽  
pp. 333-353 ◽  
Author(s):  
Stephen Macdonald ◽  
Briony Birdi
Keyword(s):  
Literature Review ◽  
Design Methodology ◽  
Information Science ◽  
Social Institutions ◽  
Future Research ◽  
Library And Information Science ◽  
New Approach ◽  
Content Type ◽  
Normative Framework ◽  
Contextual Awareness

Purpose Neutrality is a much debated value in library and information science (LIS). The “neutrality debate” is characterised by opinionated discussions in contrasting contexts. The purpose of this paper is to fill a gap in the literature by bringing these conceptions together holistically, with potential to deepen understanding of LIS neutrality. Design/methodology/approach First, a literature review identified conceptions of neutrality reported in the LIS literature. Second, seven phenomenographic interviews with LIS professionals were conducted across three professional sectors. To maximise variation, each sector comprised at least one interview with a professional of five or fewer years’ experience and one with ten or more years’ experience. Third, conceptions from the literature and interviews were compared for similarities and disparities. Findings In four conceptions, each were found in the literature and interviews. In the literature, these were labelled: “favourable”, “tacit value”, “social institutions” and “value-laden profession”, whilst in interviews they were labelled: “core value”, “subservient”, “ambivalent”, and “hidden values”. The study’s main finding notes the “ambivalent” conception in interviews is not captured by a largely polarised literature, which oversimplifies neutrality’s complexity. To accommodate this complexity, it is suggested that future research should look to reconcile perceptions from either side of the “neutral non-neutral divide” through an inclusive normative framework. Originality/value This study’s value lies in its descriptive methodology, which brings LIS neutrality together in a holistic framework. This framework brings a contextual awareness to LIS neutrality lacking in previous research. This awareness has the potential to change the tone of the LIS neutrality debate.

Development of insect repellent finish by a simple coacervation microencapsulation technique

2018 ◽  
Vol 30 (2) ◽  
pp. 152-158 ◽  
Author(s):  
Rachna Sharma ◽  
Alka Goel
Keyword(s):  
Essential Oils ◽  
Design Methodology ◽  
Insect Repellent ◽  
New Approach ◽  
Content Type ◽  
Eucalyptus Oil ◽  
Gum Acacia ◽  
Major Benefit ◽  
Natural Insecticide ◽  
Practical Implications

Purpose The paper focused onto the development of microcapsules by using two essential oils. It proposes the uses of eucalyptus oil and cedarwood oil as a natural insecticide. The purpose of this paper is to demonstrate the application of developed microcapsules to impart insect repellency on textile substrate. Design/methodology/approach The paper opted for an experimental study using two essential oils and gum in formations of microcapsules through a simple coaseravtion encapsulation technique. The developed solution was analyzed, including confirmation of size and structure through. Application of developed finish on substrate was also undertaken to prove better ability as repellent fabric. Findings The paper highlights useful invention of microencapsulated fabric developed with the combination of gum acacia and eucalyptus oil as core and shell material. The developed fabric has better ability to repel silverfish as compared to microencapsulated fabric developed with gum acacia (shell) and cedarwood oil (core). Research limitations/implications Due to the lack of time and less availability of essential oils, only two oils were used to test the insect repellent behavior. Practical implications This paper fulfills an identified need, it includes implications for the development of a very useful natural insecticide to repel silverfish (Lepisma saccharina) insect. This insect is a very common problem found in cloth wardrobes and bookshelves; it mainly attacks the fabric with cellulosic content and starch. Social implications Society will get major benefit of using these microencapsulated finished fabrics, which repel silverfish from their home and keep their clothing and books safe for longer period. The natural fragrance and medicinal benefits of these essential oils can never be ignored. Originality/value This study sets a new approach to repel insects like silverfish from the bookshelves and clothing wardrobes. A layer of insect repellent microencapsulated finished fabric can be added in these shelves and wardrobes. It is an eco-friendly approach of using natural essential oils instead of chemical insecticides.

scholarly journals Organizational diversity: making the case for contextual interpretivism

2015 ◽  
Vol 34 (6) ◽  
pp. 496-509 ◽  
Author(s):  
W. J. Greeff
Keyword(s):  
Diversity Management ◽  
Internal Communication ◽  
Organizational Diversity ◽  
New Approach ◽  
Content Type ◽  
Organizational Contexts ◽  
Organizational Settings ◽  
Managing Diversity ◽  
Functional Aspects ◽  
Excellence Theory

Purpose – The purpose of this paper is to make a case for contextual interpretivism in managing diversity in organizational settings, specifically in its bearing on internal communication, going against the dominating functionalistic stance of venerated and ubiquitous approaches. Design/methodology/approach – Qualitative and quantitative methodologies were employed to explore the potential of contextual interpretivism within the mining and construction industries of South Africa, due to the fecund diversity context of its employee population. Findings – This paper points to the enriched understanding that could result from following a contextual interpretivistic approach to internal communication for diversity management, and in so doing discusses the ways in which this could take hold in organizations through the application of germane theoretical assertions of revered internal organizational communication literature, specifically the excellence theory and communication satisfaction. Research limitations/implications – The main limitation to this research is the restricted generalizability of its empirical research. Further research is required for the exploration of the central premise in other organizational contexts. Practical implications – The paper provides insights into the ways in which organizations could approach its diversity management so as to speak to more than just the functional aspects thereof, and rather to the importance of nurturing an understanding of employees’ interpretation of the organization’s diversity endeavors. Originality/value – The implications of applying a new approach to diversity management in organizational settings is discussed and argued, offering an empirical application thereof, which gives way to practical, data-driven recommendations for use in organizational settings.

A multi-manned assembly line balancing problem with classified teams: a new approach

2016 ◽  
Vol 36 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Hamid Yilmaz ◽  
Mustafa Yilmaz
Keyword(s):  
Design Methodology ◽  
Assembly Line ◽  
Assembly Line Balancing ◽  
Line Balancing ◽  
Test Problems ◽  
New Approach ◽  
Content Type ◽  
Line Test ◽  
Assembly Line Balancing Problem ◽  
First Time

Purpose – Within team-oriented approaches, tasks are assigned to teams before being assigned to workstations as a reality of industry. So it becomes clear, which workers assemble which tasks. Design/methodology/approach – Team numbers of the assembly line can increase with the number of tasks, but at the same time, due to physical situations of the stations, there will be limitations of maximum working team numbers in a station. For this purpose, heuristic assembly line balancing (ALB) procedure is used and mathematical model is developed for the problem. Findings – Well-known assembly line test problems widely used in the literature are solved to indicate the effectiveness and applicability of the proposed approach in practice. Originality/value – This paper draws attention to ALB problem in which workers have been assigned to teams in advance due to the need for specialized skills or equipment on the line for the first time.

scholarly journals The convection of a Bingham fluid in a differentially-heated porous cavity

2016 ◽  
Vol 26 (3/4) ◽  
pp. 879-896 ◽  
Author(s):  
D. Andrew S. Rees
Keyword(s):  
Rayleigh Number ◽  
Yield Stress ◽  
Piecewise Linear ◽  
Rectangular Cavity ◽  
Content Type ◽  
Multigrid Algorithm ◽  
Bingham Number ◽  
Steady Solutions ◽  
Darcy Flux ◽  
Darcy Rayleigh Number

Purpose – The purpose of this paper is to determine the manner in which a yield stress fluid begins convecting when it saturates a porous medium. A sidewall-heated rectangular cavity is selected as the testbed for this pioneering work. Design/methodology/approach – Steady solutions are obtained using a second order accurate finite difference method, line relaxation based on the Gauss-Seidel smoother, a Full Approximation Scheme multigrid algorithm with V-cycling and a regularization of the Darcy-Bingham model to smooth the piecewise linear relation between the Darcy flux and the applied body forces. Findings – While Newtonian fluids always convect whenever the Darcy-Rayleigh number is nonzero, Bingham fluids are found to convect only when the Darcy-Rayleigh number exceeds a value which is linearly dependent on both the Rees-Bingham number and the overall perimeter of the rectangular cavity. Stagnation is always found in the centre of the cavity and in regions close to the four corners. Care must be taken over the selection of the regularization constant. Research limitations/implications – The Darcy-Rayleigh number is restricted to values which are at or below 200. Originality/value – This is the first investigation of the effect of yield stress on nonlinear convection in porous media.

Dynamic capabilities vs. innovation capability: are they related?

2014 ◽  
Vol 21 (3) ◽  
pp. 368-384 ◽  
Author(s):  
Lidija Breznik ◽  
Robert D. Hisrich
Keyword(s):  
Literature Review ◽  
Design Methodology ◽  
Dynamic Capabilities ◽  
Dynamic Capability ◽  
Future Research ◽  
Innovation Capability ◽  
New Approach ◽  
Content Type ◽  
New Research ◽  
The Relationship

Purpose – The purpose of this paper is to provide insights into the relationship between dynamic capabilities and innovation capabilities. It links dynamic capability with innovation capability and indicates the ways they can be related. Design/methodology/approach – The relationships between dynamic and innovation capability were investigated through a systematic literature review. Findings – The review indicates that common characteristics exist between of the both fields, which demonstrate six relationships. Additionally, findings show some inconsistencies and even contradictions. Originality/value – In this paper, the authors have compared dynamic capabilities, a relatively new approach in the field of strategic management, with innovation capabilities, a widely recognised crucial domain for sustained competitiveness. Since both areas address issues that are essential to today's environment, future research should seek to clarify both concepts, by undertaking some new research and developing comprehensive and unambiguous framework.

scholarly journals New approach in the application of lignin for the synthesis of hybrid materials

2017 ◽  
Vol 89 (1) ◽  
pp. 161-171 ◽  
Author(s):  
Beata Podkościelna ◽  
Marta Goliszek ◽  
Olena Sevastyanova
Keyword(s):  
Suspension Polymerization ◽  
Nitrogen Adsorption ◽  
Experimental Protocol ◽  
New Approach ◽  
Surface Areas ◽  
Adsorption Data ◽  
Novel Method ◽  
Derivatives Of ◽  
Polymerization Method ◽  
Nitrogen Adsorption Data

AbstractIn this study, a novel method for the synthesis of hybrid, porous microspheres, including divinylbenzene (DVB), triethoxyvinylsilane (TEVS) and methacrylated lignin (L-Met), is presented. The methacrylic derivatives of kraft lignin were obtained by reaction with methacryloyl chloride according to a new experimental protocol. The course of the modification of lignin was confirmed by attenuated total reflectance (ATR-FTIR) and nuclear magnetic resonance (NMR) spectroscopy. The emulsion-suspension polymerization method was employed to obtain copolymers of DVD, TEVS and L-Met in spherical forms. The porous structures and morphologies of the obtained lignin-containing functionalized microspheres were investigated by low-temperature nitrogen adsorption data and scanning electron microscopy (SEM). The microspheres are demonstrated to be mesoporous materials with specific surface areas in the range of 430–520 m2/g. The effects of the lignin component on the porous structure, shape, swelling and thermal properties of the microspheres were evaluated.

Coupling of Steroid O-(Carboxymethyl)oxime Derivatives with Amino Alcohols

1996 ◽  
Vol 61 (2) ◽  
pp. 288-297 ◽  
Author(s):  
Vladimír Pouzar ◽  
Ivan Černý
Keyword(s):  
Amino Acids ◽  
Hydroxy Group ◽  
Building Blocks ◽  
Amino Alcohols ◽  
New Approach ◽  
Alternative Synthesis ◽  
Oxime Derivatives ◽  
A Chain ◽  
Derivatives Of

New approach to the preparation of steroids with connecting bridge, based on an O-carboxymethyloxime (CMO) structure, and with terminal hydroxy group, is presented. 17-CMO derivatives of 3β-acetoxy- and 3β-methoxymethoxyandrost-5-en-17-one were condensed with α,ω-amino alcohols to give derivatives with a chain of seven to nine atoms. After THP-protection, these compounds were converted to 3-keto-4-ene derivatives. An alternative synthesis consisted in transformation of 17-CMO derivatives with bonded amino acids by reduction of the terminal carboxyl. The resulting compounds were designed as building blocks for the preparation of bis-haptens for sandwich immunoassays.

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