Omer A. Elsayed, Kijung Kwon, Waqar Asrar and Ashraf A. Omar
The paper aims to compute rolling moments on a follower aircraft wing due to vortices generated by a plain and flapped NACA4412 wing using experimental particle image velocimetery…
Abstract
Purpose
The paper aims to compute rolling moments on a follower aircraft wing due to vortices generated by a plain and flapped NACA4412 wing using experimental particle image velocimetery (PIV) data.
Design/methodology/approach
This paper describes the detailed variation of the induced rolling moment on a follower aircraft wing derived from a PIV velocity field measurement. A rectangular wing of a subsonic wall interference model is used as a vortex generator in two different configurations: plain wing of NACA4412 cross‐section profile; and flapped wing with trailing edge flap of NACA0012 cross‐section profile extended at 20°.
Findings
Results obtained showed that the maximum induced rolling moment coefficient depends on the strength of the vortex produced by the generating aircraft wing and increases linearly with the increment of the angle of attack.
Originality/value
This paper provides an insight on the effects of different angles of attacks for plain and flapped wings on the induced rolling moment coefficient and therefore, the hazard imposed on the following aircraft can be estimated.
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Keywords
Mahmood K. Mawlood, Shahnor Basri, Waqar Asrar, Ashraf A. Omar, Ahmad S. Mokhtar and Megat M.H.M. Ahmad
To develop a high‐order compact finite‐difference method for solving flow problems containing shock waves.
Abstract
Purpose
To develop a high‐order compact finite‐difference method for solving flow problems containing shock waves.
Design/methodology/approach
A numerical algorithm based on high‐order compact finite‐difference schemes is developed for solving Navier‐Stokes equations in two‐dimensional space. The convective flux terms are discretized by using advection upstream splitting method (AUSM). The developed method is then used to compute some example laminar flow problems. The problems considered have a range of Mach number that corresponds to subsonic incompressible flow to hypersonic compressible flows that contain shock waves and shock/boundary‐layer interaction.
Findings
The paper shows that the AUSM flux splitting and high‐order compact finite‐difference methods can be used accurately and robustly in resolving shear layers and capturing shock waves. The highly diffusive nature of conventional flux splitting especially on coarse grids makes them inaccurate for boundary layers even with high‐order discretization.
Originality/value
This paper presents a high‐order numerical method that can accurately and robustly capture shock waves without deteriorating oscillations and resolve boundary layers and shock/boundary layer interaction.
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Mahmood K. Mawlood, ShahNor Basri, Waqar Asrar, Ashraf A. Omar, Ahmad S. Mokhtar and Megat M.H.M. Ahmad
A high‐order compact upwind algorithm is developed for solving Navier‐Stokes equations in two‐space dimensions. The method is based on advection upstream splitting method and…
Abstract
A high‐order compact upwind algorithm is developed for solving Navier‐Stokes equations in two‐space dimensions. The method is based on advection upstream splitting method and fourth‐order compact finite‐difference schemes. The convection flux terms of the Navier‐Stokes equations are discretized by a compact cell‐centered differencing scheme while the diffusion flux terms are discretized by a central fourth‐order compact scheme. The midpoint values of the flux functions required by the cell‐centered compact scheme are determined by a fourth‐order MUSCL approach. For steady‐state solutions; first‐order implicit time integration, with LU decomposition, is employed. Computed results for a laminar flow past a flat plate and the problem of shock‐wave boundary layer interaction are presented.
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Eman Omar Rayan, Adla Mohamed Ragab and Ashraf Samir Anwar
The twenty-first century manifests two of the challenging issues about achieving Sustainable Local Economic Development (SLED) and turning to environmental sustainability through…
Abstract
Purpose
The twenty-first century manifests two of the challenging issues about achieving Sustainable Local Economic Development (SLED) and turning to environmental sustainability through Green Job Creation (GJC). The study examines that not only are both challenges are urgent, but they are also intimately linked and will have to be addressed together. It also finds out that further factors like Managerial Effectiveness (ME) and Public Policy Effectiveness (PPE) affect GJC.
Design/methodology/approach
The study uses qualitative and quantitative methods by utilizing primary data collected through designing questionnaires answered by random executives and citizens of three governorates; Cairo, Alexandria and Beni-Suef. These governorates are chosen because they represent different Egyptian geographic areas, i.e. the capital of Egypt, lower and Upper Egypt, where there are numbers of industrial zones with many heavy polluting industrial activities that exist.
Findings
The study showed that there is a lack of effectiveness and efficiency in applying common international standards in GJC’s strategies in Cairo, Alexandria and Beni-Suef. Additionally, it is highly recommended that the three governorates enhance the exploitation of their economic resources. Quantitatively, the study showed a positive and statistically-significant connection between SLED and GJC, alongside with a positive and statistically-significant connection between ME and GJC.
Originality/value
The study provides empirical evidence about the main requirements in designing an efficient framework for achieving eco-friendly local economic activities and suggesting practical solutions to obstacles that face local strategies regarding the study’s variables.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/IJSE-01-2020-0012
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The Prophet Muhammad (pbuh) laid the foundations of the Islamic state in Medina in 622 A.D. The state expanded gradually during the 10‐year rule of the Prophet (pbuh). The Arabian…
Abstract
The Prophet Muhammad (pbuh) laid the foundations of the Islamic state in Medina in 622 A.D. The state expanded gradually during the 10‐year rule of the Prophet (pbuh). The Arabian Peninsula and Southern Palestine were conquered during that period. The state expanded enormously during the reign of Umar (RA). Many countries of the Roman and Persian empires comprising an area of more than 2.2 million were annexed. Historians have noted that this framework played a vital role in integrating these people which in turn strengthened the state.
The militants' losses demonstrate their resilience rather than weakness. Kabul is trying to restart talks with the Taliban and assert ownership of the process. Whether the Taliban…
Details
DOI: 10.1108/OXAN-DB221907
ISSN: 2633-304X
Keywords
Geographic
Topical
Anwar ul-Haque, Waqar Asrar, Ashraf Ali Omar, Erwin Sulaeman and JS Mohamed Ali
Realistic data bank of aerodynamic and stability derivatives is still missing for hybrid buoyant aerial vehicles. Such vehicles take-off and land similar to an aircraft with their…
Abstract
Purpose
Realistic data bank of aerodynamic and stability derivatives is still missing for hybrid buoyant aerial vehicles. Such vehicles take-off and land similar to an aircraft with their partial weight balanced by the aerostatic lift. The purpose of this paper is to use wind tunnel testing for a better understanding of the aerodynamic and static stability behavior of such vehicles.
Design/methodology/approach
The effect of wing on the aerodynamic and static stability characteristics of a clean configuration hybrid buoyant is analyzed. The free stream velocity is 20 m/s, and ranges of angle of attack and side slip angle are from −8° to 12° and ±16°, respectively. Data are corrected to account for the effect of strut interference and zero load condition. The maximum blockage of the model with respect to the cross-section area of the test section is about 2.7 per cent.
Findings
A hybrid model manufactured by using wood and metal is an optimum solution with less number of parts. The vehicle is statically, longitudinally and directionally stable. Wings designed to fulfill the partial requirement of lift contribute significantly to counter the huge moment generated by the voluminous hull for centre of gravity location ahead of the leading edge of the wing.
Research limitations/implications
There are number of manufacturing constraints for scaling down a model of a hybrid buoyant aerial vehicle configuration. Specially, the thickness of the wing limits the testing envelop of angle of attack and free stream velocity.
Practical implications
The data presented here are a preliminary guide for further work on larger size models. The data may also be used to build and perform flight tests on small full-scale instrumented models and to obtain flight dynamics data.
Originality/value
The estimated aerodynamic and stability derivatives and slopes can be utilized in future for multidisciplinary design.
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Mehree Iqbal, Louis Geneste and Paull Weber
This paper aims to contribute to the field of social entrepreneurship by exploring the interrelationships among the antecedents of social entrepreneurial intention (SEI) through…
Abstract
Purpose
This paper aims to contribute to the field of social entrepreneurship by exploring the interrelationships among the antecedents of social entrepreneurial intention (SEI) through the lens of Mair Noboa model (MNM). In recent years, many researchers have applied the antecedents of MNM to determine SEI. However, interrelationship among these antecedents has not been a focus of enquiry despite the repeated scholarly calls.
Design/methodology/approach
Applying quantitative methodology, the data was collected from a Web-based survey distributed across Bangladesh (N = 412). Data analysis was carried out based on the covariance-based structural equation modelling technique to confirm the hypotheses. The final measurement and structural models met all the requirements for reliability, model fit, convergent validity and discriminant validity. The proposed hypotheses were tested based on direct relationships and mediating effects.
Findings
The findings suggested that interrelationships among these antecedents do increase individuals’ intentions to become social entrepreneurs.
Originality/value
This paper fills an important knowledge gap by exploring the interrelationships among moral obligation, empathy, perceived social support and social entrepreneurial self-efficacy. This paper stressed identifying whether the SEI enhances through the interrelationships among these antecedents or not. The study findings bring new theoretical and practical implications on the role of empathy, moral obligation, perceived social support and social entrepreneurial self-efficacy.
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US President Donald Trump, like his predecessor, is pursuing a strategy of forcing the Afghan Taliban to a military standstill and using that advantage to press for a negotiated…