Influence of the pressure relief door area and aspect ratio on discharge and force characteristics

2019 ◽  
Vol 92 (2) ◽  
pp. 107-116
Author(s):  
Shiyu Feng ◽  
Chenchen Wang ◽  
Xiaotian Peng ◽  
Yan Yan ◽  
Yang Deng ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Discharge Coefficient ◽  
Geometric Parameters ◽  
Pressure Relief ◽  
Thrust Coefficient ◽  
Content Type ◽  
Moment Coefficient ◽  
The Moment ◽  
Compartment Pressures ◽  
Force Characteristics

Purpose The purpose of this paper is to analyze the effects of the PRD geometric parameters, including the area and aspect ratio, on the discharge and force characteristics of pressure relief process under various plenum compartment pressures and Mach numbers. Design/methodology/approach Under various plenum compartment pressures and Mach numbers, the effect of the area and aspect ratio on the discharge and force characteristics of the PRD are numerically investigated via a three-dimensional steady Reynolds-averaged Navier–Stokes equations solver based on structured grid technology. Findings When the aspect ratio remains constant, the discharge coefficient CD, thrust coefficient CT and moment coefficient CM are not affected by the PRD. When the area is constant, the aspect ratio dramatically impacts the discharge and force characteristics because the aspect ratio increases, the discharge coefficient CD of the PRD decreases, and the thrust coefficient CT and the moment coefficient CM both increase. When the aspect ratio is 2, the discharge coefficient CD decreases by 14.7 per cent, the thrust coefficient CT increases by 10-15 per cent, and the moment coefficient CM increases by 10-23 per cent compared with when the aspect ratio is 1. Practical implications This study provides detailed data and conclusions for nacelle PRD researchers and actual engineering applications. Originality/value On the basis of considering the influence of operating conditions on the discharge and force characteristics of the nacelle PRD, the impact of geometric parameters, including the area and aspect ratio on the discharge and force characteristics is comprehensively considered.

Friction Drag on Bladed Disks in Housings as a Function of Reynolds Number, Axial and Radial Clearance, and Blade Aspect Ratio and Solidity

1961 ◽  
Vol 83 (4) ◽  
pp. 719-723 ◽  
Author(s):  
Robert W. Mann ◽  
Charles H. Marston
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Rotating Disk ◽  
Radial Clearance ◽  
Disk Radius ◽  
Moment Coefficient ◽  
Aspect Ratios ◽  
Direct Measurements ◽  
Partial Admission ◽  
The Moment

Extra losses from partial admission operation of a gas turbine occur both in the nozzle flow arc and away from it. The latter have been related to the theory of fluid flow over a rotating disk expressing a dimensionless moment coefficient as a function of Reynolds number. By direct measurements of drag torque, the moment coefficient has been determined over a range of Reynolds number from 2.0 × 104 to 4.5 × 106 for several aspect ratios, axial and radial shroud clearances, and solidities. Losses increase with increasing aspect ratio. Small increases from minimum practical clearance have little effect, but blade pumping losses become severe at radial and axial clearances of the order of half the disk radius. Typical changes in solidity have only small effects on losses.

The parameter identification model considering both geometric parameters and joint stiffness

2019 ◽  
Vol 47 (1) ◽  
pp. 76-81
Author(s):  
Jing Bai ◽  
Le Fan ◽  
Shuyang Zhang ◽  
Zengcui Wang ◽  
Xiansheng Qin
Keyword(s):  
Parameter Identification ◽  
Industrial Robot ◽  
Joint Stiffness ◽  
Geometric Parameters ◽  
Least Square ◽  
Experimental Result ◽  
Positional Accuracy ◽  
Content Type ◽  
The Absolute ◽  
Identification Model

Purpose Both geometric and non-geometric parameters have noticeable influence on the absolute positional accuracy of 6-dof articulated industrial robot. This paper aims to enhance it and improve the applicability in the field of flexible assembling processing and parts fabrication by developing a more practical parameter identification model. Design/methodology/approach The model is developed by considering both geometric parameters and joint stiffness; geometric parameters contain 27 parameters and the parallelism problem between axes 2 and 3 is involved by introducing a new parameter. The joint stiffness, as the non-geometric parameter considered in this paper, is considered by regarding the industrial robot as a rigid linkage and flexible joint model and adds six parameters. The model is formulated as the form of error via linearization. Findings The performance of the proposed model is validated by an experiment which is developed on KUKA KR500-3 robot. An experiment is implemented by measuring 20 positions in the work space of this robot, obtaining least-square solution of measured positions by the software MATLAB and comparing the result with the solution without considering joint stiffness. It illustrates that the identification model considering both joint stiffness and geometric parameters can modify the theoretical position of robots more accurately, where the error is within 0.5 mm in this case, and the volatility is also reduced. Originality/value A new parameter identification model is proposed and verified. According to the experimental result, the absolute positional accuracy can be remarkably enhanced and the stability of the results can be improved, which provide more accurate parameter identification for calibration and further application.

Sensor e-textiles: person centered co-design for people with late stage dementia

2016 ◽  
Vol 20 (2) ◽  
pp. 76-85 ◽  
Author(s):  
Cathy Treadaway ◽  
Gail Kenning
Keyword(s):  
Design Process ◽  
Late Stage ◽  
Design Methodology ◽  
Design Research ◽  
Family Members ◽  
Sensory Properties ◽  
Content Type ◽  
People With Dementia ◽  
Grounded Practical Theory ◽  
The Moment

Purpose – The purpose of this paper is to present design research investigating the development of sensory textiles with embedded electronics to support the wellbeing of people with late stage dementia in residential care. Design/methodology/approach – The research presented is qualitative and uses a mixed method approach informed by grounded practical theory and positive design methodologies. It uses an inclusive and participatory co-design process involving people with dementia and their families with an interdisciplinary team of experts. Findings – Both the co-design process and the artefacts developed have been beneficial in supporting wellbeing. The textile artefacts have been found to soothe, distract and comfort people with dementia. They have also been shown to facilitate in the moment conversational bridges between family members and carers with persons with dementia. Research limitations/implications – The findings are based on a small cohort of participants, observational reports and descriptive accounts from family members and carers. Practical implications – The paper proposes ways in which simple hand-crafted textiles can be used beneficially to support the wellbeing of people with late stage dementia. It provides examples of how technology can be used to personalise and extend the sensory properties of the artefacts created. Social implications – It promotes an inclusive co-design methodology involving care professionals, carers and people with dementia with designers and technologists. Originality/value – The paper describes new ways of extending sensory properties of textiles through the integration of technology.

Investigation of sustainability of lubricated journal bearing under relevant design parameters

2018 ◽  
Vol 70 (4) ◽  
pp. 789-804 ◽  
Author(s):  
M.M. Shahin ◽  
Mohammad Asaduzzaman Chowdhury ◽  
Md. Arefin Kowser ◽  
Uttam Kumar Debnath ◽  
M.H. Monir
Keyword(s):  
Aspect Ratio ◽  
Elastic Strain ◽  
Journal Bearing ◽  
Design Parameters ◽  
Content Type ◽  
Computational Fluid Dynamics Cfd ◽  
Stress Formation ◽  
Bearing Design ◽  
The Stability ◽  
Bearing Friction

Purpose The purposes of the present study are to ensure higher sustainability of journal bearings under different applied loads and to observe bearing performances such as elastic strain, total deformation and stress formation. Design/methodology/approach A journal bearing test rig was used to determine the effect of the applied load on the bearing friction, film thickness, lubricant film pressure, etc. A steady-state analysis was performed to obtain the bearing performance. Findings An efficient aspect ratio (L/D) range was obtained to increase the durability or the stability of the bearing while the bearing is in the working condition by using SAE 5W-30 oil. The results from the study were compared with previous studies in which different types of oil and water, such as Newtonian fluid (NF), magnetorheological fluid (MRF) and nonmagnetorheological fluid (NMRF), were used as the lubricant. To ensure a preferable aspect ratio range (0.25-0.50), a computational fluid dynamics (CFD) analysis was conducted by ANSYS; the results show a lower elastic strain and deformation within the preferable aspect ratio (0.25-0.50) rather than a higher aspect ratio using the SAE 5W-30 oil. Originality/value It is expected that the findings of this study will contribute to the improvement of the bearing design and the bearing lubricating system.

Identification of asset life cycle stage: case study in heavy-duty truck fleet

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Oscar Daniel Rivera Baena ◽  
Maria Valentina Clavijo Mesa ◽  
Carmen Elena Patino Rodriguez ◽  
Fernando Jesus Guevara Carazas
Keyword(s):  
Life Cycle ◽  
Design Methodology ◽  
Life Cycle Stage ◽  
Waste Collection ◽  
Content Type ◽  
Heavy Duty Truck ◽  
Maintenance Work ◽  
Operational Decision Making ◽  
The Moment

PurposeThis paper aims to determine the stage of the life cycle where the trucks of a waste collection fleet from a Colombian city are located through a reliability approach. The reliability analysis and the evaluation of curve of operational costs allow to know the moment in which it is necessary to make decisions regarding an asset, its maintenance or possible replacement.Design/methodology/approachFor a dataset presented as maintenance work orders, the time to failures (TTFs) for each vehicle in the fleet were calculated. Then, a probability density function for those TTFs was fitted to locate each vehicle in a region of the bathtub curve and to calculate the reliability of the whole fleet. A general functional analysis was also developed to understand the function of the vehicles.FindingsIt was possible to determine that the largest proportion of the fleet was in the final stage of the life cycle, in this sense, the entire fleet represent critical assets which in most of cases could be worth replacement or overhaul.Originality/valueIn this study, an address is exposed for the identification of critical equipment by reliability and statistical analysis. This analysis is also integrated with the maintenance management process. This is a broadly interested topic since it allows to support the maintenance and operational decision-making process, indicating the focus of resource allocation all over the entire asset life cycle.

Social capital in the theory and research of LIS professionals in the light of the literature on the subject. Review of current knowledge

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Maja Dorota Wojciechowska
Keyword(s):  
Social Capital ◽  
Current Knowledge ◽  
Future Research ◽  
Content Type ◽  
Individual Social Capital ◽  
Rural Libraries ◽  
The Subject ◽  
The Moment ◽  
The Impact

Purpose The purpose of the paper is to present the latest scholarly trends in the field of social capital in libraries, to review research concepts published by LIS professionals and to suggest further research possibilities in this area. Design/methodology/approach This paper presents a review and critical analysis of literature associated with research on social capital in libraries to highlight its importance for the development of LIS and its impact on the functioning of environments linked with various types of libraries. The goal of literature analysis was to determine the current condition of research on social capital in libraries. The main trends were identified and the need for further qualitative analyses, which are missing at the moment, was confirmed. Findings It was determined that, so far, LIS professionals have focussed mainly on the role of municipal libraries in developing social capital, the problem of building trust, especially in immigrant circles and the impact of libraries on promoting a civil society. Academic libraries, rural libraries, organisational capital in libraries and individual social capital of librarians were a much less frequent subject of research. The role of libraries in developing social capital in educational (primary and secondary education) and professional (non-university professionals) circles is practically non-existent in research, and it will require in-depth studies and analyses in the coming years. Originality/value This paper constitutes a synthetic review of the latest research concepts concerning social capital in libraries. It identifies the most important research trends and areas that so far have not been explored and suggests research methods to help LIS professionals design future research in this area more effectively.

Effects of air mattress pressure on sleep quality and physiological responses: comparison of shoulder and hip pressure relief

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yoon Jeong Baek ◽  
Seung-Hyun Kim ◽  
Sayup Kim ◽  
Eui-Sang Yoo ◽  
Joo-Young Lee
Keyword(s):  
Sleep Quality ◽  
Surface Pressure ◽  
Pressure Control ◽  
Body Region ◽  
High Quality ◽  
Pressure Relief ◽  
Content Type ◽  
Quality Sleep ◽  
Improve Sleep Quality

PurposeThe purpose of the present study was to evaluate the effect of air mattress pressure on sleep quality.Design/methodology/approachTen young healthy males participated in all hard surface [AH], shoulder soft [SS] and shoulder and hip soft mattress [SHS] conditions. The surface pressure for SS and SHS were set at their preferred levels.FindingsThe results showed that sleep efficiencies were over 95% for all the three conditions; there were no significant differences in individual sleep variables among the three conditions, but overall sleep quality was better for SS than AH (p = 0.065); heart rates during sleep was greater for AH than the other two conditions (p < 0.1); and a stronger relationship between clothing and bed microclimate humidity were found for SS and SHS than that for AH.Research limitations/implicationsThese results indicated that the both pressure relief air mattresses that were set at their own preferred levels provided high quality sleep with no marked differences.Practical implicationsAir pressure relief mattresses can improve sleep quality of healthy individuals during sleep at night. The results can be used to understand appropriate pressure distribution on surface mattress according to body region, and also to develop algorithms to provide optimum sleep using mattresses with surface pressure control by body region.Originality/valueThe present study found that the shoulder and/or hip pressure relief air mattresses that were set at their own preferred levels provided high quality sleep with no marked differences.

Numerical and experimental study on the effect of surface texture with roughness orientation considered under a mixed lubrication state

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Junru Wang ◽  
Quandai Wang ◽  
Yueyan Li ◽  
Meiling Guo ◽  
Pengyang Li ◽  
...  
Keyword(s):  
Surface Texture ◽  
Surface Texturing ◽  
Mixed Lubrication ◽  
Laser Surface ◽  
Geometric Parameters ◽  
Laser Surface Texturing ◽  
Textured Surface ◽  
Asperity Contact ◽  
Content Type ◽  
Texture Parameters

Purpose The purpose of this paper is to investigate the effects of surface texture with roughness orientation considered on tribological properties under a mixed lubrication state numerically and experimentally. Design/methodology/approach Based on the average Reynolds equation and asperity contact model, the impacts of surface texture parameters and roughness orientation on lubrication properties have been calculated using finite difference method. Tin–bronze samples with various prescribed surface texture geometric parameters and roughness orientation were fabricated by laser surface texturing technique, and the tribology performance of the textured surface was studied experimentally. Findings The effects of surface geometric parameters and roughness orientation parameters have been discerned. The experimental observations are in good agreement with the numerical prediction, which suggests that the numerical scheme adopted in this work is suitable in capturing the surface texture and roughness effect under mixed lubrication state. Originality/value By meticulously controlling the surface roughness and surface texture geometric characteristics based on the laser surface texturing process, samples with prescribed surface texture parameters and roughness orientation consistent with that in theoretical studies were fabricated and the theoretical model and results were verified experimentally.

A new jig-shape optimization method for the high aspect ratio wing

2018 ◽  
Vol 91 (1) ◽  
pp. 124-133
Author(s):  
Zhe Yuan ◽  
Shihui Huo ◽  
Jianting Ren
Keyword(s):  
Aspect Ratio ◽  
Shape Optimization ◽  
High Aspect Ratio ◽  
Optimization Design ◽  
Design Method ◽  
Aircraft Design ◽  
Optimization Method ◽  
Attack Angle ◽  
Structural Deformation ◽  
Content Type

Purpose Computational efficiency is always the major concern in aircraft design. The purpose of this research is to investigate an efficient jig-shape optimization design method. A new jig-shape optimization method is presented in the current study and its application on the high aspect ratio wing is discussed. Design/methodology/approach First, the effects of bending and torsion on aerodynamic distribution were discussed. The effect of bending deformation was equivalent to the change of attack angle through a new equivalent method. The equivalent attack angle showed a linear dependence on the quadratic function of bending. Then, a new jig-shape optimization method taking integrated structural deformation into account was proposed. The method was realized by four substeps: object decomposition, optimization design, inversion and evaluation. Findings After the new jig-shape optimization design, both aerodynamic distribution and structural configuration have satisfactory results. Meanwhile, the method takes both bending and torsion deformation into account. Practical implications The new jig-shape optimization method can be well used for the high aspect ratio wing. Originality/value The new method is an innovation based on the traditional single parameter design method. It is suitable for engineering application.

Open access to scientific information: comparative study in DOAJ

2014 ◽  
Vol 35 (4/5) ◽  
pp. 364-374 ◽  
Author(s):  
Tereza Stoyanova Trencheva ◽  
Tania Yordanova Todorova
Keyword(s):  
Open Access ◽  
Comparative Study ◽  
Scientific Information ◽  
Comparative Approach ◽  
Content Type ◽  
Open Access Journals ◽  
Global Movement ◽  
The Difference ◽  
Important Position ◽  
The Moment

Purpose – The purpose of the paper is to provide a comparative retrospective analysis of Bulgarian, Turkish and Croatian Open Access (OA) journals added in Directory of Open Access journals (DOAJ) in the period 2002-2013. Design/methodology/approach – First of all, the study is focussed on brief review of definitions and descriptions of the OA as a global movement. In the study were analyzed the three main OA initiatives and was shown the difference between Golden Road and Green Road. Second of all, the authors used the comparative approach and made a comparative study of the OA journals in Bulgaria, Turkey and Croatia and present the evaluation results and findings. Findings – Qualitative and quantitative data for the study are collected by the DOAJ. The data are analyzed in terms of quantity and period, and the results are presented graphically and tabular and finally there are made major specific conclusions and recommendations. Originality/value – The paper shows that OA in the digital space has an important position in scientific research. There are many discussion issues related to the problems of OA, but overall study of OA to scientific information, and in particular comparative study of Bulgarian, Turkish and Croatian journals in the DOAJ does not exist at the moment.

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