Yazar "Aygun, Hakan" seçeneğine göre listele

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    Analysis of cruise conditions on energy, exergy and NOx emission parameters of a turbofan engine for middle-range aircraft
    (Energy, 2022) Aygun, Hakan; Turan, Onder
    Studying efficiency and emissions of an aircraft engine at cruise phase is of high importance so as to help in finding optimum flight conditions. Especially, since exhaust emissions from the engine lead to climate change, quantifying exhaust emissions could show adverse effect of the aero-engine on environment. In this study, en- ergetic and exergetic behaviour of high by-pass turbofan are parametrically examined. Besides, cruise NOx emission is measured by P3-T3, Boeing Fuel Flow Method 2 (BFFM2) and DLR methods. Moreover, the index as Specific NOx Production (SNP) is quantified for the turbofan engine. Thanks to this parameter, NOx effect of the engine is compared according to different flight conditions. For this aim, parametric cycle equations and emission calculation methods regarding turbofan engine are encoded so as to determine performance outputs for Mach changing from 0.7 to 0.9 and altitude between 9000 m and 11,000 m. According to performance results, the average specific fuel consumption (SFC) regarding turbofan engine is predicted as 19.65 g/kN.s at 9 km and 19.68 g/kN.s at 11 km. As for exergo-sustainability index, environmental effect factor is calculated as 1.19 at 9 km and 1.26 at 11 km. Also, the average cruise NOx emission index is found as 16.66 g/kg at 9 km and 13.93 g/ kg at 11 km. Finally, the mean SNP regarding the turbofan is measured as 0.5071 g/kN.s at 9 km and 0.3374 g/ kN.s at 11 km. The findings of this study provide useful insights to comprehend effects of flight conditions on aircraft emissions. In terms of environmental sustainability, decision mechanism could be enhanced to find out optimum flight conditions thanks to the presented results.
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    Application of exergetic analysis to inverted Brayton cycle engine at different flight conditions
    (Elsevier, 2023) Karabacak, Mustafa; Kirmizi, Mehmet; Aygun, Hakan; Turan, Onder
    The aviation sector has continued to be modernized by overcoming technological challenges involving strict constraints for mission requirements. In this context, the great attention to newly proposed methods which the requirements satisfied has been drawn in the related aviation field. As a novelty, performance and exergy an alyses of inverted Brayton cycle engine (IBCE) are investigated at supersonic speed (2.5 M) by comparing it with a conventional afterburning turbojet engine (CATE) in this study. Moreover, exergy analysis is performed solely for the IBCE at 5 M where only the IBCE could generate thrust. According to performance findings, specific fuel consumption (SFC) of the CATE changes from 57.97 g/kNs and 71.72 g/kNs whereas it raises from 51.76 g/kNs and 56.57 g/kNs for the IBCE due to variation of turbine inlet temperature (TIT) and afterburner exit temper ature (AET) at 2.5 M. Also, thermal efficiency of the CATE varies approximately between 32.97% and 46.73% while that of IBCE changes between 50.72% and 58.43% for IBCE at 2.5 M. At hypersonic speed, SFC of the IBCE is measured to vary between 71.34 g/kN and 85.49 g/kN at 5 of Mach. Lastly, the exergy efficiency of IBCE changes between 23.73% and 27.70% at same conditions. Where the higher TIT leads to lowering it whereas the higher AET provides increment of exergy efficiency. This study shows that thanks to cycle change, gas turbine engines could provide more advantages for new generation aircraft compared with conventional ones.
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    Effects of design parameters on thermal parameters for an adaptive cycle turbofan
    (Springer Science and Business Media B.V., 2023) Aygun, Hakan; Ekmekçi, İsmail; Turan, Önder
    In this study, effects of high-pressure compressor pressure ratio (HPC PR) and bypass ratio (BPR) regarding adaptive cycle turbofan (ACT) engine on performance parameters and second law parameters of thermodynamics involving Carnot, Curzon–Ahlborn, Caputo, thermal and exergy efficiencies are dealt with. For this aim, HPC PR changes between 4 and 6, and bypass ratio ranges between 0.3 and 0.6. At same altitude of 10,000 m, comparative analysis is performed for efficiency behavior of ACT engine at military mode (MM) and afterburner mode (ABM). Better understanding of performance improvements of a military aircraft can be possible by investigating these efficencies for different design variables. Based on these computations, environmental and irreversibility parameters involving specific irreversibility production and environmental effect factor regarding ACT engine are dealt with at both modes. According to performance outcomes, SFC of the ACT engine decreases by 7.66% at MM, whereas it increases by 0.34% at ABM due to higher BPR. Moreover, it diminishes by 4.98% at MM and decreases by 0.42% at ABM with influence of the elevated HPC PR. As for efficiency analyses, exergy efficiency of ACT engine increases from 20.04 to 21.7% at MM, whereas it decreases 17.43 to 17.37% at ABM with effect of raised BPR. The higher HPC PR leads to increase from 20.32 to 21.38% at MM and from 17.39 to 17.46% at ABM. Among the components, the combustor has the lowest exergy efficiency, which is favorably affected from both variables at MM. Finally, environmental effect factor of the ACT becomes lower thanks to the higher BPR and HPC PR at MM. However, at ABM, to increase these variables do not result in lower EEF. Therefore, considering design parameters according to operation modes could lead in finding more meaningful outcomes. It is thought that this study helps in analyzing of thermodynamic parameters with respect to different design parameters.
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    Energy and performance analysis of a turbofan engine with the aid of dynamic component efficiencies
    (Elsevier Ltd, 2022) Cihangir, Serhan Ahmet; Aygun, Hakan; Turan, Onder
    Assessment of performance of turbofan engine with different design parameters is crucial for meeting the performance requirements by considering each key components of the engine. To comprehend influences of component efficiencies to mitigate environmental effect from turbofans has been hot topics in aviation field recently. In this study, firstly, impacts of polytropic efficiencies of fan, compressor and turbine as well as pressure ratio of combustor (CPR) on several turbofan performance are dealt with at several flight conditions. Secondly, it is tried to show difference of performance metrics under ideal and real conditions. The discrepancy between performance parameters computed at ideal and real cases gets relatively high. Namely, at take-off condition, the difference between ideal and real specific fuel consumption is computed as 29.12% whereas it is found as 28.37% at cruise condition, which shows that considering the system as ideal makes the computations inappropriate for performance analysis. Moreover, performance parameters of turbofan is more sensitive to compressor efficiency compared with turbine. As the polytropic efficiencies of fan and compressor are close to highest, net thrust of the engine develops from 109.05 kN (baseline) to 124.71 kN at take-off while it increases from 26.36 kN (baseline) to 29.27 kN at cruise condition. With effect of the elevated pressure ratio of combustor and efficiency of turbine, thrust of the engine increases to 118.23 kN at take off and to 27.84 kN at cruise condition. Finally, as Mach number increases, the difference between ideal and real performance values sharply increases. Therefore, when analyzing on turbofan engines, the assumptions should be minimum as possible as, otherwise the findings make the engineers to misguide for system optimization. Besides, these outcomes show that if the components with higher polytropic efficiency can be obtained, overall efficiency of turbofan, thereby environmental sustainability could be elevated to upper level compared with baseline.
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    Energy and performance optimization of an adaptive cycle engine for next generation combat aircraft
    (PERGAMON-ELSEVIER SCIENCE LTD, 2020) Aygun, Hakan; Cilgin, Mehmet Emin; Ekmekci, Ismail; Turan, Onder
    For next generation aircraft, Adaptive Cycle Engine (ACE) is a candidate to fulfill the multi-mission requirements of flight. This new concept is promising to complete deficiencies of conventional low by-pass mixed turbofan engines because the ACE model incorporates different thermodynamic cycles (turbojet and turbofan) on the same air vehicle system. Firstly, performance and design results of the ACE model are compared with those of fixed cycle low by-pass turbofan engine by using specific fuel consumption (SFC), specific thrust (ST), power and efficiency parameters. Moreover, verification of the newly developed ACE model is performed. Secondly, considering some design parameters, ST and SFC values of the ACE model are analyzed for double by-pass mode (DBM) and single by-pass mode (SBM). Considering performance analysis of the ACE, SFC value is determined as 17.85 g/kN.s at DBM and 42.18 g/kN.s at SBM. According to results of energy analysis, overall efficiency of the ACE is calculated as 23% for DBM and 9% for SBM whereas fixed cycle engine has 18% for military mode and 7% for afterburner mode. Finally, minimization of (SFC) is obtained with genetic algorithm approach. Based on the design variables such as by-pass ratio and turbine inlet temperature, minimum SFC value for the ACE model is calculated as 17.41 g/kN.s at DBM and 40.45 g/kN.s at SBM. (C) 2020 Elsevier Ltd. All rights reserved.
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    Performance and energy analysis of turboprop engine for air freighter aircraft with the aid of multiple regression
    (Elsevier, 2023) Kirmizi, Mehmet; Aygun, Hakan; Turan, Onder
    In this study, performance and energy analyses of a turboprop engine (TPE) are determined for an air freighter aircraft. For this aim, influences of different design variables involving turbine inlet temperature (TIT) ranging 1200 K and 1400 K, pressure ratio of compressor (CPR) ranging 16 and 20 and propeller efficiency (PE) ranging from 0.7 to 0.98 are elaborately searched, which helps in observing changes of specific fuel consumption (SFC), thrust force, engine power and overall efficiency related to the turboprop engine at an altitude of 6.7 km and 0.59 Mach. Based on this analysis, relations of these parameters with the mentioned design variables are researched with multiple regression method. In the light of performance results, SFC of the TPE changes from 0.2449 kg/kW.h to 0.1844 kg/kW.h due to rising PE and diminishes from 0.2263 kg/kW.h to 0.2159 kg/kW.h owing to rising TIT. On the other hand, overall efficiency of the TPE increases from 21% to approximately 40% due to rising PE and enhances from 26.3% to 28.12% due to rising TIT whereas it decreased from 27.6% to 23.5% due to increasing the CPR. Finally, the linear modeling of both SFC and overall efficiency regarding TPE with pairs of TIT and CPR variables results in about 0.97 of coefficient of determination (R2 ) whereas it is improved to more than 0.99 of R2 by using quadratic modeling. Moreover, for the modeling involving PE variable, R2 is computed as 0.99 with linear equations. Therefore, quadratic modeling enables R2 to slightly increase. It is thought that this analysis could benefit in knowing how much design parameters are effective on turboprop performance indicators.
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    Propeller effects on energy, exergy and sustainability parameters of a small turboprop engine
    (Elsevier Ltd, 2022) Aygun, Hakan; Kirmizi, Mehmet; Turan, Onder
    Turboprop engines have been commonly adopted for several applications such as unmanned aerial vehicle and commuter aircraft. In this study, the effects of propeller efficiency (PEF) with various compressor pressure ratio (CPR) are examined for energetic, exergetic, environmental and sustainability indicators of a small turboprop engine (S-TPE) at sea level. For this aim, PEF of the S-TPE has the range varying between 0.7 and 0.95 whereas its CPR has boundary changing between 10 and 12.5. According to performance results, thrust of the S-TPE changes from 5.11 kN to 6.88 kN due to rising PEF and from diminishes from 5.9 kN to 5.68 kN due to rising CPR whereas overall efficiency of the S-TPE alters from 22.1% to 29.7% owing to the PEF effect and from 24.7% to 25.5% owing to the CPR effect. On the other hand, exergetic parameters of the components of the engine remain constant with the PEF effect whereas both effects (PEF and CPR) are observed on exergetic metrics of the whole engine. In this context, exergy efficiency of the combustor increases from 84.83% to 86.7% due to only the CPR effect. Moreover, exergy efficiency of the S-TPE experiences the increase from 21.39% to 28.77% due to rising PEF while it raises from 23.99% to 24.71% due to rising CPR. Finally, specific wasted exergy of the S-TPE decreases from 0.7566 MW/kN to 0.5624 MW/kN with the effect of PEF whereas it drops from 0.6751 MW/kN to 0.6540 MW/kN with the effect of CPR. These findings show that a small change in design variables reflects on energetic and exergetic performance of the engine at different degrees.
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    Stage-based exergy analysis for a modern turboprop engine under various loading
    (Pergamon-Elsevier Science Ltd, 2024) Kirmizi, Mehmet; Aygun, Hakan; Turan, Onder
    Enhancements in propulsion systems have played a key role in promoting aircraft fuel efficiency, which serves to achieve global decarbonization goals. In particular, investigation by decoupling individual components of the whole engine explicitly provides insight about improvement potential. In this study, stage-based exergetic assessments of the turbomachinery components such as compressor and turbine for a large turboprop engine used in military cargo aircraft are performed for five different flight cases. As a novelty, a new index called specific irreversibility ratio (SIR) showing irreversibility per unit power is established. In this regard, exergy efficiency of compressor changes from 86.6 % to 96.3 % throughout the 14 stages whereas for whole compressor, it is measured as 89.3 %. On the other hand, exergy efficiency of gas turbine changes from 92.5 % to 91.8 % throughout 2 stages whereas, for power turbine, it varies from 89.1 % to 89.7 % throughout 2 stages. Moreover, SIR of air compressor diminishes from 12.94 % to 4.26 % throughout 14 stages whereas those of gas turbine and power turbine increase from 8.17 % to 8.84 % and from 11.52 % to 12.58 % along with two stages, respectively. As for effect of flight cases, exergy efficiency of whole compressor changes by 2 % whereas those of gas and power turbines vary by 0.2 % and 0.5 %, respectively throughout flight cases. However, improvement potential rate of air compressor experiences a change between 23.81 kW and 58.19 kW whereas it varies between 27.31 kW and 50.74 kW for gas turbine and between 26.24 kW and 36.23 kW for power turbine. It could be inferred that variation of exergetic metrics throughout stages is more apparent in comparison with those of flight cases. The methodology improved in this study could help in understanding stage-based efficiency of turbomachinery components at on-design and off-design conditions.