Person: IŞIKLI, FIRAT
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IŞIKLI
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FIRAT
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Publication Electronic driver design of a piezo-actuated valve mechanism for continuously variable valve timing(Ieee, 2019-01-01) Dirim, B.; Sürmen, A.; Karamangil, M. I.; Avcı, A.; İkli, F. I.; Tekin, M.; Türköz, N.; Dirim, Bayazit; SÜRMEN, ALİ; KARAMANGİL, MEHMET İHSAN; AVCI, AYFER; TEKİN, MERVE; Türköz, N.; IŞIKLI, FIRAT; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0003-1662-5649; 0000-0003-2831-3175; 0000-0002-9009-8069; AAH-8619-2019; KFR-7212-2024; JCN-8081-2023; AAG-8571-2021; HNS-2001-2023; EBD-3489-2022; EJZ-3309-2022Volumetric efficiency is the main parameter that characterizes the increase in power of an engine at the same speed. A group of design parameters that affects the volumetric efficiency are opening-closing characteristics of the valves (opening and closing times, valve lift and shape of cam lobe). But the same values of these parameters in various speeds yield different volumetric values which make the problem much more difficult. The solution is to develop techniques that change these parameters with changing engine speed. The most ideal one is to achieve this variation continuously together with speed variation which is called continuously variable valve timing (CVVT). To achieve this goal piezo actuator driven hydraulic displacement magnifier has been used. To drive the piezo actuator an electronic control unit and high voltage power amplifier designed and then fully digital solution is developed and explained in this study.Publication Modelling and performance analysis of an electric vehicle powered by a PEM fuel cell on new european driving cycle (NEDC)(Springer, 2021-03-17) Işıklı, Fırat; Sürmen, Ali; Gelen, Ayetül; IŞIKLI, FIRAT; SÜRMEN, ALİ; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0003-1662-5649; HNS-2001-2023; JCN-8081-2023Modelling of a complete polymer electrolyte membrane fuel cell (PEMFC) power systems and performance of the models when subjected to common driving cycle are important research issues. In this study a complete PEMFC system, including air and hydrogen supply equipment, fuel cell stack, electrical system and a 75 kW car, is modelled. An efficiency map of a brand new electric motor is directly imported into the model for it. MATLAB & Simulink tools, based on this mathematical model of PEMFC, are used to establish a dynamic model for a vehicle which is electrically supplied by the fuel cell according to cruise characteristics of New European Driving Cycle (NEDC). Model results show significant instabilities during transient operation regarding the late response of the air supply system. Obtained stack characteristics are similar to those obtained in similar studies conducted previously. Performance results of the car based on energy consumption shows perfect agreement with the results of another model developed for an electric vehicle of the same weight and run also on NEDC.Publication Experimental analysis of the volumetric and thermal efficiency performance of a novel direct piezo-acting cvvt mechanism(Taylor & Francis Inc, 2023-06-22) Sürmen, Ali; SÜRMEN, ALİ; Karamangil, M., I; KARAMANGİL, MEHMET İHSAN; Avcı, A.; AVCI, ATAKAN; Dirim, B.; DİRİM, MEHMET SABRİ; Işıklı, F.; IŞIKLI, FIRAT; Tekin, M.; TEKİN, MERVE; Türköz, N.; Mühendislik Fakültesi; Makine Mühendisliği Bölümü; 0000-0003-1662-5649; 0000-0003-2831-3175; 0000-0002-9009-8069; AAH-8619-2019; AAG-8571-2021; JCN-8081-2023; HNS-2001-2023In this study, a specifically designed direct-acting continuously variable valve timing mechanism was used to determine speed optimised valve timings for best volumetric efficiency of an engine. This mechanism basically consists of a piezo stack and a hydraulic magnifier integrated into it. To avoid effects of excessive vibrations on the piezo-stack, the engine was operated in a non-combustion mode. An electric motor was used to power the engine. Some system limitations of the hydraulic magnifier and the piezo-stack were the main challenges to a non-stop operation. A valve lift of approximately 4 mm, obtained with maximum applicable voltage of 600V to the piezo-stack, was referred to for comparison instead of the 7.6 mm original value. Tests were conducted for 30 inlet valve timing combinations at four different engine speeds from 1500 to 3000 rpm with 500 rpm increments. Timing pairs for the best VE were determined. They yielded 11.5% to 19.4% better volumetric efficiencies at 4mm lift than those obtained with the original valve timing of the cold engine. We also predicted 5-11.5% overall efficiency improvement, depending on engine type and operating conditions. Despite some practical challenges, better VE values have been obtained for a specific engine at varied speeds.