Profile URL: https://hdl.handle.net/20.500.13091/11784
Job Title:Dr. Öğr. Gör.
Email Address:aonder@ktun.edu.tr
Main Affiliation:07. 16. Department of Machinery and Metal Technologies
Status: Current Staff
ORCID:
0000-0001-8419-6896
0000-0001-8419-6896Scopus ID:
57222167697
57222167697YÖK Akademik: E60FF951DCB228E2
Google Scholar:
I3ESfCcAAAAJ
I3ESfCcAAAAJWeb of Science ID:
HMP-2944-2023
HMP-2944-2023Name Variants:
Onder, Ahmet
10 results
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Article Citation - WoS: 13Citation - Scopus: 16The Fuzzy Logic-Based Modeling of a Micro-Scale Sloped Solar Chimney Power Plant(KOREAN SOC MECHANICAL ENGINEERS, 2021-02-27) Güzel, Muhammed Hüseyin; Ünal Ercan, Hatice; Önder, Ahmet; Şen, Muhammed Arif; Köse, Faruk; Unal, Recep EmreThe energy demand of world is increasing worldwide because of increasing population and developing technology. The use of environmentally friendly renewable resources is very important in providing the increasing energy needs. In the renewable energy sources, the solar energy has a strategic importance because of its huge potential and unlimited. The production of electrical energy by solar chimney power plants is one of the reliable and profitable methods. Fuzzy logic-based approaches are commonly used for modeling different systems in many fields. Also, a renewable energy system can be modelled by fuzzy definitions. In this way, it can provide efficiently and quickly theoretical estimates of systems with productive simulations. In this study, using the experimental data obtained from the micro-scale sloped solar chimney power plant in carried on scientific research project by authors, the obtaining and verifying a fuzzy logic-based model (FLBM) that can calculate the change in air velocity at turbine according to the change of radiation and temperature is presented. The air velocity at the turbine inlet is the considerable variable determining the electricity generation in a solar chimney. Thus, the output of the model is determined as this air velocity. In changes in the radiation and temperature values are defined as inputs. A two input-one output fuzzy model is obtained, in which the inference method is designed in the form of Mamdani and the membership functions in the form of the triangle, making inferences according to the rule base determined by the experience achieved from the experimentally studies. In order to investigate the accuracy of the FLBM, the simulation results and the data get from experimental setup in April 2019 are compared and evaluated. The validation of the FLBM compared to the experimental system is investigated using different error evaluation criteria. It is proved that the results of FLBM and experimental data are realized at a high rate (95.95 %) close to each other and similarly.Master Thesis Hidrodinamik Kaymalı Yataklı Santrifüj Kan Pompası Tasarımı ve Hidrolik Performansının Belirlenmesi(Konya Teknik Üniversitesi, 2019) Önder, Ahmet; Yapıcı, RafetSon yıllarda insan sağlığını olumsuz etkileyen rahatsızlıklardan birisi kalp yetmezliğidir. Kalp yetmezliği, kalp performansının azalması sonucu kalbin doku ve organlara yeterli kanı pompalayamaması durumudur. Kalbin yeterli kanı pompalayabilmesi için kan pompalarını içeren kalp destek cihazları kullanılmaktadır. Kan pompaları, kalp performansını desteklemek için vücut içine yerleştirilebildiği gibi vücut dışında da kullanılabilir. Bu çalışmada; kan pompası tasarımı için gerekli parametreler 5 L/dak hacimsel debi, 3000 dev/dak dönme sayısı ve 100 mmHg basma yüksekliği olarak belirlenmiştir. Hidrodinamik kaymalı yataklı santrifüj bir kan pompasının tüm elemanlarının katı modelleri oluşturulmuş ve hesaplamalı akışkanlar dinamiği (HAD) ile ön analizleri yapılmıştır. Yarı açık çarklı monoblok kan pompasının prototipi üretilmiştir. Pompanın yataklama elemanı olarak hidrodinamik kaymalı yataklama tekniği tercih edilmiştir. İki farklı test akışkanı kullanılan deney düzeneğinde; Newton tipi test akışkanı için su-gliserin çözeltisi (hacimce %40 gliserin ve %60 su) ve Newton tipi olmayan test akışkanı için su-ksantan çözelti (kütlece %0,06 ksantan sakızı) kullanılmıştır. Her iki akışkan için pompanın dört farklı dönme sayısında hidrolik performansları belirlenmiştir. Tasarım debisinde HAD sonuçları ile deney sonuçları karşılaştırılmıştır. Elde edilen verilere göre sonuçların birbirleri ile uyumlu olduğu görülmüştür. Tasarım parametresinde; deneysel hidrolik verim, Newton tipi akışkan için %35.8 ve Newton tipi olmayan akışkan için %34.4 olarak belirlenmiştir.Article Citation - WoS: 8Citation - Scopus: 9An Experimental Performance Comparison of Newtonian and Non-Newtonian Fluids on a Centrifugal Blood Pump(Sage Publications Ltd, 2022-01-11) Önder, Ahmet; Yapıcı, Rafet; İncebay, ÖmerThe use of substitute fluid with similar rheological properties instead of blood is important due to ethical concerns and high blood volume consumption in pump performance test before clinical applications. The performance of a centrifugal blood pump with hydrodynamic journal bearing is experimentally tested using Newtonian 40% aqueous glycerin solution (GS) and non-Newtonian aqueous xanthan gum solution of 600 ppm (XGS) as working fluids. Experiments are performed at four different rotational speeds which are 2700, 3000, 3300, and 3600 rpm; experiments using GS reach between 8.5% and 37.2% higher head curve than experiments using the XGS for every rotational speed. It was observed that as the rotational speed and flow rate increase, the head curve difference between GS and XGS decreases. This result can be attributed to the friction reduction effect when using XGS in experiments at high rotation speed and high flow rate. Moreover, due to different fluid viscosities, differences in hydraulic efficiency were observed for both fluids. This study reveals that the use of Newtonian fluids as working fluids is not sufficient to determine the actual performance of a blood pump, and the performance effects of non-Newtonian fluids are remarkably important in pump performance optimizations.Book Part Experimental Investigation of the Overall Efficiency of a Centrifugal Blood Pump Using Glycerin Solution and Xanthan Gum Solutions as Blood Analog Fluid(Springer, 2025) Onder, A.; Incebay, O.; Yapici, R.The most critical issues to consider in the design of the blood pumps are the hydraulic performance and hemocompatibility of the pump. It is important to perform hydraulic performance tests during the blood pump development process before clinical applications. Using substitute fluids instead of blood as the working fluid during the testing of blood pumps provides convenience for the tests. In this study, solid models of all components of a centrifugal blood pump were designed, and then the pump volute and impeller were manufactured. The hydraulic performance of the manufactured centrifugal blood pump is experimentally tested using an aqueous glycerin solution and xanthan gum solution as working fluids. The overall efficiency of the pump at four rotation speeds which are 2700, 3000, 3300, and 3600 rpm was determined for both fluids. Experiments were carried out in the flow rate range of 1–8 L/min. The experimental overall efficiencies of the two working fluids were compared at all rotational speeds and throughout the flow rate range. As a result of the study, there were approximately 2% differences in overall efficiency for the two working fluids at the same rotational speeds and flow rates. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.Article Citation - WoS: 10Citation - Scopus: 14Heuristic Optimization of Impeller Sidewall Gaps-Based on the Bees Algorithm for a Centrifugal Blood Pump by Cfd(SAGE PUBLICATIONS LTD, 2021-06-15) Önder, Ahmet; İncebay, Ömer; Şen, Muhammed Arif; Yapıcı, Rafet; Kalyoncu, MeteOptimization studies on blood pumps that require complex designs are gradually increasing in number. The essential design criteria of centrifugal blood pump are minimum shear stress with maximal efficiency. The geometry design of impeller sidewall gaps (blade tip clearance, axial gap, radial gap) is highly effective with regard to these two criteria. Therefore, unlike methods such as trial and error, the optimal dimensions of these gaps should be adjusted via a heuristic method, giving more effective results. In this study, the optimal gaps that can ensure these two design criteria with The Bees Algorithm (BA), which is a population-based heuristic method, are investigated. Firstly, a Computational Fluid Dynamics (CFD) analysis of sample pump models, which are selected according to the orthogonal array and pre-designed with different gaps, are performed. The dimensions of the gaps are optimized through this mathematical model. The simulation results for the improved pump model are nearly identical to those predicted by the BA. The improved pump model, as designed with the optimal gap dimensions so obtained, is able to meet the design criteria better than all existing sample pumps. Thanks to the optimal gap dimensions, it has been observed that compared to average values, it has provided a 42% reduction in aWSS and a 20% increase in efficiency. Moreover, original an approach to the design of impeller sidewall gaps was developed. The results show that computational costs have been significantly reduced by using the BA in blood pump geometry design.Article Citation - WoS: 1Citation - Scopus: 2FUZZY LOGIC-BASED MODELING OF A CENTRIFUGAL BLOOD PUMP PERFORMANCE VIA EXPERIMENTAL DATA OF NEWTONIAN AND NON-NEWTONIAN FLUIDS(World Scientific Publ Co Pte Ltd, 2022) Önder, Ahmet; Güzel, Muhammed Huseyin; İncebay, Omer; Sen, Muhammed Arif; Yapıcı, Rafet; Kalyoncu, MeteUsing fuzzy logic methods, some complex experiments that are not possible due to critical limitations can be simulated in a short time. In this study, experimental data of Newtonian 40% aqueous glycerin solution (GS) and non-Newtonian 600ppm aqueous xanthan gum solution (XGS) working fluids were used to model the hydraulic performance of a centrifugal blood pump. A novel fuzzy logic-based model (FLM) for modeling the hydraulic performance of the pump model is proposed. In the proposed model, there are two inputs which are flow rate and impeller rotational speed and one output which is head pressure. In FLM, the range for flow rate is 1-7.8L/min in GS and 1-8L/min in XGS, and for head pressure 50-245mmHg in GS and 50-215mmHg in XGS. In addition, impeller rotational speed range is 2700-3600rpm for both fluids. The estimated results with FLM were validated with the experimental results and it was seen that the FLM was compatible with the experimental results with an accuracy of 96.25%. These results imply that the developed FLM is acceptable and can be used to assist in determining the performance of blood pumps.Article Shape Optimization of a Centrifugal Blood Pump Impeller Using an Adaptive Neuro-Fuzzy Inference System and Genetic Algorithm(Sage Publications Ltd., 2026) Onder, Ahmet; Yapici, RafetApproaches commonly used in the design and optimization of centrifugal blood pumps, based on manual selection of design parameters or systematic modification of design configurations, aim to identify the best candidate among a restricted set of design points rather than the global optimum. In contrast, automated optimization techniques aim to reach the near-global optimum by exploring the design space from a broader perspective while identifying the best parameter combinations with minimal human intervention. This study presents an automated procedure developed for the blade optimization of a centrifugal blood pump by integrating an adaptive neuro-fuzzy inference system modeling with a genetic algorithm. A baseline pump model was designed using conventional turbomachinery methods to meet the requirements of a left ventricular assist device. Geometric variations were generated using a Latin Hypercube Sampling approach, and computational fluid dynamics simulations were carried out to produce a dataset covering pressure head, hydraulic efficiency, and hemolysis index. These performance parameters were incorporated into the optimization framework, enabling simultaneous evaluation. The optimized impeller blade geometry demonstrated notable improvements over the baseline pump, including a 7.2% increase in pressure head, a 2.4% enhancement in hydraulic efficiency, and a 4.78% reduction in hemolysis index. Flow field analyses indicated reduced recirculation and improved suction performance, as well as decreased hemolysis accumulation near the impeller blade outlet. The results indicate that the simultaneous use of machine learning and evolutionary optimization has the potential to enable the design of centrifugal blood pumps with improved hydraulic and hemolytic performance.Doctoral Thesis Santrifüj Sol Ventriküler Bir Destek Cihazının Hemolitik ve Hidrolik Performans Optimizasyonu(2026) Önder, Ahmet; Yapici, RafetVentriküler destek cihazlarının geliştirilmesinde hidrolik performans ve kan uyumluluğu temel performans kriterleri arasında yer almaktadır. Bu tez çalışmasında, sol ventriküler destek cihazlarında (LVAD) kullanılmak üzere tasarlanan bir santrifüj kan pompasında hidrolik ve hemolitik performansın eş zamanlı olarak iyileştirilmesi amaçlanmıştır. Bu amaç doğrultusunda, çark geometrisinin hidrolik verim ve hemoliz indeksi üzerindeki etkileri hesaplamalı akışkanlar dinamiği (HAD) tekniği ve deneysel çalışmalar ile incelenmiştir. Tez çalışması kapsamında ilk olarak, sayısal hemoliz tahmin yaklaşımının belirlenmesi amacıyla Amerika Birleşik Devletleri Gıda ve İlaç İdaresi tarafından tanımlanan kıyaslama santrifüj kan pompası modeli üzerinde HAD analizleri gerçekleştirilmiş ve kuvvet yasası hemoliz modelinde farklı kayma gerilmesi tanımları ile katsayı setleri karşılaştırmalı olarak değerlendirilmiştir. Daha sonra fizyolojik çalışma koşullarını sağlayan bir temel santrifüj kan pompası modeli geleneksel türbomakine tasarım yöntemleri kullanılarak tasarlanmıştır. Temel pompa geometrisi esas alınarak, çark kanadı geometrisini tanımlayan kanat giriş açısı, kanat çıkış açısı, kanat giriş yüksekliği, kanat çıkış yüksekliği ve kanat kalınlığı tasarım değişkenleri olarak belirlenmiştir. Tasarım uzayı Latin hiperküp örnekleme yöntemi kullanılarak örneklenmiş ve parametrik tasarım varyasyonları oluşturulmuştur. Oluşturulan tasarım varyasyonlarının basınç farkı, hidrolik verimi ve hemoliz indeksi HAD analizleri ile belirlenmiş ve elde edilen sayısal veriler kullanılarak uyarlamalı ağ tabanlı bulanık çıkarım sistemi (ANFIS) tabanlı modeller oluşturulmuştur. Bu modeller genetik algoritma (GA) ile gerçekleştirilen optimizasyon sürecinde vekil modeller olarak kullanılmış ve hidrolik verim ile hemoliz indeksini birlikte ele alan optimum çark geometrisi belirlenmiştir. Temel ve optimum pompa geometrilerine ait hidrolik ve hemolitik performanslar, farklı çalışma koşullarında gerçekleştirilen HAD simülasyonları ile incelenmiştir. Sayısal olarak elde edilen temel ve optimum pompa geometrilerinin deneysel olarak incelenebilmesi amacıyla modüler bir LVAD prototipi geliştirilmiş ve üretilmiştir. Temel ve optimum çark geometrilerine sahip prototiplerin hidrolik ve hemolitik performanslarını belirlemek amacıyla hidrolik performans testleri ve in vitro kan testleri gerçekleştirilmiştir. Tez çalışması sonucunda, LVAD'lerde kullanılan santrifüj kan pompalarında hidrolik ve hemolitik performansın eş zamanlı olarak iyileştirilebileceği sayısal ve deneysel bulgularla ortaya konmuştur. Temel ve optimum pompa geometrilerine ait hidrolik ve hemolitik performanslar, farklı dönme hızları ve debilerde gerçekleştirilen HAD simülasyonları ile karşılaştırmalı olarak değerlendirilmiştir. ANFIS-GA tabanlı optimizasyon yaklaşımı sonucunda elde edilen optimum çark geometrisinin, temel tasarıma kıyasla tasarım noktasında (4500 dev/dak, 5 L/dak) basınç farkını %7,2 ve hidrolik verimi %2,4 artırırken hemoliz indeksini %4,78 azalttığı HAD analizleri ile belirlenmiştir. Deneysel hidrolik performans testlerinde, çalışma aralığı içerisinde her iki pompa geometrisi için maksimum pompa-motor sistem veriminin 5000 dev/dak dönme hızında ve 5,76 L/dak debide elde edildiği belirlenmiştir. Bu koşullarda maksimum pompa-motor sistem verimi temel çark geometrisine sahip prototip için %13,81, optimum çark geometrisine sahip prototip için ise %14,73 olarak belirlenmiştir. Tasarım noktasında gerçekleştirilen in vitro kan testlerinde optimum çark geometrisine sahip LVAD prototipi için normalize edilmiş hemoliz indeksi değeri 0,353 g/100 L, temel çark geometrisine sahip prototip için ise 0,426 g/100 L olarak belirlenmiştir. Ayrıca tasarım noktasında HAD analizleri ile deneysel ölçümler arasında basınç farkı değerleri açısından temel ve optimum prototipler için sırasıyla %2,05 ve %4,83 fark elde edilmiş; böylece sayısal sonuçların deneysel verilerle iyi uyum gösterdiği anlaşılmıştır. Elde edilen bulgular, çark kanadı geometrisinin santrifüj kan pompalarında hidrolik ve hemolitik performansın iyileştirilmesi açısından kritik bir tasarım parametresi olduğunu göstermektedirArticle Citation - WoS: 1Citation - Scopus: 2Computational Fluid Dynamics Simulating of the Fda Benchmark Blood Pump With Different Coefficient Sets and Scaler Shear Stress Models Used in the Power-Law Hemolysis Model(Springer Japan Kk, 2024-08-23) Önder, Ahmet; İncebay, Ömer; Yapıcı, RafetHemolysis is the most important issue to consider in the design and optimization of blood-contacting devices. Although the use of Computational Fluid Dynamics (CFD) in hemolysis prediction studies provides convenience and has promising potential, it is an extremely challenging process. Hemolysis predictions with CFD depend on the mesh, implementation method, coefficient set, and scalar-shear-stress model. To this end, an attempt was made to find the combination that would provide the most accurate result in hemolysis prediction with the commonly cited power-law based hemolysis model. In the hemolysis predictions conducted using CFD on the Food and Drug Administration (FDA) benchmark blood pump, 3 different scalar-shear-stress models, and 5 different coefficient sets with the power-law based hemolysis model were used. Also, a mesh independence test based on hemolysis and pressure head was performed. The pressure head results of CFD simulations were compared with published pressure head of the FDA benchmark blood pump and a good agreement was observed. In addition, results of CFD-hemolysis predictions which are conducted with scalar-shear-stress model and coefficient set combinations were compared with experimental hemolysis data at three operating conditions such as 6-7 L/min flow rates at 3500 rpm rotational speeds and 6 L/min at 2500 rpm. One of the combinations of the scalar-shear-stress model and the coefficient set was found to be within the error limits of the experimental measurements, while all other combinations overestimated hemolysis.Article Citation - WoS: 6Citation - Scopus: 7Fuzzy-Based Modeling and Speed Optimization of a Centrifugal Blood Pump Using a Modified and Constrained Bees Algorithm(Elsevier Ireland Ltd, 2022) İncebay, Ömer; Önder, Ahmet; Arif, Şen, Muhammed; Yapıcı, Rafet; Kalyoncu, Mete; Sen, Muhammed Arif; Arif Sen, MuhammedBackground and objective: Side effects that may occur when using blood pumps for treatment of patients are the main limitations on pump rotational speed determination. Efforts are being made to reduce side effects in both design and usage procedures. In determining the pump speed for treatment, decreasing the pressure on the main artery and preserving the valve functions are taken into consideration. In addition to these, the parameters considered for design which include pump efficiency and mechanical effects on blood cells, should also be taken into consideration. In this study, the aim is to obtain the optimum pump speed for the maximum hydraulic efficiency and minimum wall shear stresses that occur inside the pump. Methods: Blood pump modeling based on fuzzy logic is created on the hydraulic performance data of a centrifugal blood pump, whose design, CFD analysis, manufacture and experimental testing have been performed previously. Using this fuzzy logic model, the optimum pump speeds were determined using the Bees Algorithm, an intuitive optimization algorithm, in the operating range 1-7 L/min fluid flow rate. In the optimization process, the aim is to achieve minimum shear stress with maximal efficiency. Intravascular pressure limits (90-160 mm-Hg) were set as pressure constraints. Results: The optimum operating point is obtained as a 3350 rpm pump speed and a 4.35 L/min flow rate. At this operating point, CFD simulation is performed, and maximum wall shear stress was found to be 1458 Pa and its efficiency as 34.2%. Conclusions: In addition to the parameters commonly used in the pump speed optimization of blood pumps, the use of wall shear stresses and pump efficiency can provide certain improvements. © 2022
Research Topics
Domains
Physical SciencesHealth Sciences
Fields
EngineeringMedicineMaterials Science
Subfields
Biomedical EngineeringMechanics of MaterialsCardiology and Cardiovascular MedicineMechanical EngineeringPolymers and Plastics
Specific Research Areas
Mechanical Circulatory Support Devices
Cavitation Phenomena in Pumps
Cardiovascular Function and Risk Factors
Hydraulic and Pneumatic Systems
Conducting polymers and applications
Sustainable Development Goals
7AFFORDABLE AND CLEAN ENERGY
1
Research Products
3GOOD HEALTH AND WELL-BEING
1
Research Products
Documents
7
Citations
50
h-index
4
Documents
7
Citations
51
Publication Collaboration
| Affiliation Name | Count |
|---|---|
| Konya Technical University | 8 |
| Izmir Institute of Technology | 3 |
| Nanyang Technological University | 3 |
| Friedrich-Alexander-Universität Erlangen-Nürnberg | 1 |
1 / 1
Data obtained from OpenAlex
| Journal | Count |
|---|---|
| Advanced Structured Materials | 1 |
| Computer Methods and Programs in Biomedicine | 1 |
| INTERNATIONAL JOURNAL OF ARTIFICIAL ORGANS | 1 |
| Journal of Artificial Organs | 1 |
| JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY | 1 |
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Scholarly Output
10
Articles
7
Views / Downloads
45/9
Supervised MSc Theses
1
Supervised PhD Theses
1
WoS Citation Count
39
Scopus Citation Count
50
Patents
0
Projects
0
WoS Citations per Publication
3.90
Scopus Citations per Publication
5.00
Open Access Source
1
Supervised Theses
2
Scopus Quartile Distribution
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