Akay, Hasan Umur
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Akay, Hasan
Hasan, Akay
Akay,Hasan
Hasan Akay
A.,Hasan
H., Akay
A., Hasan
Akay,H.
Akay H.
H.,Akay
Akay, Hasan U.
Akay, H. U.
Akay, Hasan U. U.
Hasan, Akay
Akay,Hasan
Hasan Akay
A.,Hasan
H., Akay
A., Hasan
Akay,H.
Akay H.
H.,Akay
Akay, Hasan U.
Akay, H. U.
Akay, Hasan U. U.
Job Title
Profesör Doktor
Email Address
hasan.akay@atilim.edu.tr
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Scholarly Output
13
Articles
7
Citation Count
74
Supervised Theses
1
13 results
Scholarly Output Search Results
Now showing 1 - 10 of 13
Article Citation Count: 0Improved simulation of cryogenic fluid mixing at supercritical pressures(Public Library Science, 2023) Omair, Muhammad; Akay, Hasan U. U.; Automotive EngineeringThe combustion chamber pressure of rockets, gas turbines and diesel engines is known to be above the critical pressure of fuel and oxidizers. In the case of rocket engines the fuel and/or oxidizer is often injected at cryogenic temperatures. This elevated combustion chamber pressure and low temperature demands special treatment for numerical analysis of mixing. Thus a novel implementation of an improved equation of state has been proposed which provides better estimation of densities. Experimental and numerical data from literature has been used for validation of the analysis methodology.Article Citation Count: 6Flows around moving bodies using a dynamic unstructured overset-grid method(Taylor & Francis Ltd, 2010) Liu, Jingxin; Akay, Hasan U.; Ecer, Akin; Payli, Resat U.; Automotive EngineeringIn this article, a computational fluid dynamics algorithm is presented for simulations of complex unsteady flows around rigid moving bodies using an unstructured overset-grid method. For this purpose, a highly automated, three-dimensional, tetrahedral, unstructured overset-grid method is developed with one-cell-width overlapping zone in order to model the arbitrary geometries for steady and unsteady flow simulations. A method has been described to obtain the inter-grid boundaries of the one-cell-wide overlapping zone shared by a background grid and a minor grid. In the overset-grid methodology, vector intersection algorithm and bounding box techniques have been utilised. The mesh refinement and overset-scheme conservation studies proved the accuracy and efficiency of the method developed here. The applications of the developed algorithms were also performed through simulations that included complex internal flows around a flow-control butterfly valve as well as flows in an internal combustion engine with a moving piston. Lastly, validations with experimental data were conducted for both steady and unsteady flows around rigid bodies with relative motions.Conference Object Citation Count: 0INSTRUCTOR'S VIEWS ON DIGITALIZATION OF CAMPUS; ROLES AND RECOMMENDATIONS(Iated-int Assoc Technology Education A& development, 2016) Cigdemoglu, Ceyhan; Akay, Hasan U.; Tekin, Yucel; Automotive Engineering; Public Relations and AdvertisingThis study delve into determine the faculty members' opinions on digitalization and their views on roles and recommendations to create a digital campus. An open-ended questionnaire was answered by eleven participants, and then semi-structured interviews are conducted with volunteers. In this qualitative research, the participants were purposively selected. All interview sessions were type recorded and the data was transcribed verbatim. Lack of a comprehensive project with its budgets and action plans, job descriptions are perceived as an obstacle to create a digital campus. Lack of motivation is perceived as another obstacle to design digital course contents. The respondents consider that lessons should be designed in more attractive ways through innovative teaching methods through online tools. Faculty members using more digital tools could suggest more accountable action plans for digitalization.Conference Object Citation Count: 4A phenomenological study of instructors' experiences on an open source learning management system(Elsevier Science Bv, 2011) Cigdemoglu, Ceyhan; Arslan, Harika Ozge; Akay, Hasan; Automotive Engineering; Public Relations and AdvertisingThis paper focuses on instructors' experiences on usage of an open-source Learning Management System (LMS), Moodle in their courses. The study was conducted in a private university in Ankara, Turkey where the widespread use of the Moodle has only recently started. The phenomenological design has been utilized as qualitative research method for this paper. The Participants comprised in structures from different faculties who are new users of the Moodle. Open-ended interviews were carried out, and the data was transcribed into codes and themes. The research findings indicate that instructors have different impressions from the system in terms of their effort and expectation. (C) 2011 Published by Elsevier Ltd.Article Citation Count: 0Numerical investigation of store separation from cavity problems at high speeds(Sage Publications Ltd, 2023) Abuhanieh, Saleh; Akay, Hasan U.; Automotive EngineeringIn this work, the ability of open-source CFD tools to conduct store separation simulations from cavities is evaluated and validated using a generic test case from the literature. Firstly, the ability and accuracy of these tools for solving cavity flows at high speeds are evaluated. Secondly, their competence in predicting the trajectory of a generic store from a generic deep cavity is checked. Finally, and in order to reduce the associated computational costs, a release-time dependability factor from the recent literature is studied and evaluated. The obtained results using the selected open-source CFD tools matched quite well with the wind tunnel results. Furthermore, the results show that predicting the release-time dependability using a quantified index/factor can be a potential remedy for reducing the computational cost for this type of CFD simulations.Article Citation Count: 2A new strategy for solving store separation problems using OpenFOAM(Sage Publications Ltd, 2022) Abuhanieh, Saleh; Akay, Hasan U.; Bicer, Baris; Automotive EngineeringThe ability of OpenFOAM to solve the problem of a store separating from an air vehicle (store separation problem) has been evaluated using a dynamic mesh (Overset/Chimera) technique for an industry-class (transonic and generic) benchmark test case. The major limitations of the standard libraries have been determined. To tackle these challenges, a new strategy has been proposed and implemented using only open-source libraries and tools. The strategy combines porting, modifying, and adapting an overset library from the OpenFOAM fork platform (foam-extend) to the standard OpenFOAM platform (ESI). Furthermore, in order to overcome the well-known weakness of the standard OpenFOAM compressible solvers, the newly adapted overset library was integrated with an open-source, density-based, and coupled solver (HiSA), which uses the OpenFOAM technology. Additionally, a force restrained model was developed to consider the externally applied forces on the store by the store ejectors. The accuracy of the developed strategy has been compared with wind tunnel tests and the solutions of two well-known commercial codes, showing good agreements with them. While the study has focused on simulations with inviscid Euler equations (typical of the test case considered here), the viscosity effect on the solution has also been studied with Navier-Stokes equations and compared with other results in the literature, showing minor differences. To the best of the authors' knowledge, this is the first work which studies and validates the store separation problem in transonic regime with OpenFOAM.Article A phenomenological study of instructors’ experiences on an open source learning management system(Procedia - Social and Behavioral Sciences, 2011) Çiğdemoğlu, Ceyhan; Arslan, Harika Özge; Akay, Hasan; Automotive Engineering; Public Relations and AdvertisingThis paper focuses on instructors’ experiences on usage of an open-source Learning Management System (LMS), Moodle in their courses. The study was conducted in a private university in Ankara, Turkey where the widespread use of the Moodle has only recently started. The phenomenological design has been utilized as qualitative research method for this paper. The Participants comprised in structures from different faculties who are new users of the Moodle. Open-ended interviews were carried out, and the data was transcribed into codes and themes. The research findings indicate that instructors have different impressions from the system in terms of their effort and expectation.Conference Object Citation Count: 0Effects Of Chamber Pressure Variation On Pollutant Formation In Cryogenic Combustion(Ieee, 2021) Omair, Muhammad; Akay, Hasan U.; Automotive EngineeringLiquid rocket engines have played a major role in enabling the pursuit of space exploration. Cryogenic propellants have simplified the storage in liquid rocket engines with higher densities and lower pressures. One of the main driving forces in today's engine research is the reduction of pollutants while keeping the fuel consumption as low as possible. In this study cryogenic combustion has been simulated using the `Steady Laminar Flamelet' approach. Pollutant concentrations have been evaluated at different chamber pressures. It has been shown that combustion at higher chamber pressures results in less pollutant formation.Article Citation Count: 0Improved parallel preconditioners for multidisciplinary topology optimisations(Taylor & Francis Ltd, 2016) Akay, H. U.; Oktay, E.; Manguoglu, M.; Sivas, A. A.; Automotive EngineeringTwo commonly used preconditioners were evaluated for parallel solution of linear systems of equations with high condition numbers. The test cases were derived from topology optimisation applications in multiple disciplines, where the material distribution finite element methods were used. Because in this optimisation method, the equations rapidly become ill-conditioned due to disappearance of large number of elements from the design space as the optimisations progresses, it is shown that the choice for a suitable preconditioner becomes very crucial. In an earlier work the conjugate gradient (CG) method with a Block-Jacobi preconditioner was used, in which the number of CG iterations increased rapidly with the increasing number processors. Consequently, the parallel scalability of the method deteriorated fast due to the increasing loss of interprocessor information among the increased number of processors. By replacing the Block-Jacobi preconditioner with a sparse approximate inverse preconditioner, it is shown that the number of iterations to converge became independent of the number of processors. Therefore, the parallel scalability is improved.Conference Object Citation Count: 0USE OF ICT TOOLS AND THEIR EFFECT ON TEACHING AND LEARNING; STUDENTS' AND INSTRUCTOR'S VIEWS(Iated-int Assoc Technology Education & development, 2016) Cigdemoglu, Ceyhan; Akay, Hasan U.; Automotive Engineering; Public Relations and AdvertisingThis study aims to reveal how instructors use ICT tools in their courses and determine what ICT tools they utilize as well as assessing the contribution of ICT to learning and teaching from both students' and instructors' perspectives. As a qualitative case study research, semi-structured interviews with instructors and focus group interviews with students were conducted. Both students' and instructors' responses indicated that there is a common belief that when these tools are employed, students' success will increase. Students verified that the use of educational technologies makes them to feel more successful. Instructors stated that such tools create more organized learning and alert instructor to search for best tools for students, and let course materials accessible whenever students need. Instructors stated that although there are number of factors impeding the whole utilization of ICT tools, they agree that traditional teaching is old fashioned and ineffective in these days. Based on the responses obtained, we can state that instructors lack in explaining and evaluating carefully the impact of ICT tools that may enhance or support students' in-depth learning. Their statements are generally anecdotal rather than data driven. Also, lack of motivation among faculty members due to time restrictions was perceived as obstacle to adopting ICT fully.
