Yazar "Akansu, Yahya E." seçeneğine göre listele

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    Aerodynamic and energy-efficiency-based assessment of plasma actuator's position on a NACA0015 airfoil
    (Wiley-V C H Verlag Gmbh, 2020) Akbiyik, Hurrem; Yavuz, Hakan; Akansu, Yahya E.
    In recent years, there has been an increase in the number of research papers on plasma and its use in active flow control applications. The main objective of this study is to assess the plasma actuator's position on a NACA0015 airfoil in terms of aerodynamic forces. In addition, optimization of the plasma actuator's position and its configuration are studied in order to identify the optimum configuration for improvement in lift coefficient. The experiments are conducted in an open-suction-type wind tunnel at Reynolds numbers of 48,000, 75,000, and 100,000. The plasma actuators are mounted on various positions (x/C) starting from the leading edge to trailing edge of the airfoil. The experimental results on aerodynamic force measurement are presented to illustrate the increasing lift effect of the generated plasma. It is also shown that the plasma actuators used as an active flow control device appears to shift the stall angle of the airfoil. The results of the experimental study suggest that the energy efficiency of airborne systems can be improved with the use of plasma actuators due to its increasing lift coefficient effect. This result becomes a vital finding considering that the same flight can be achieved with less fuel and less amount of environmental pollution for the same distance of journey. It is also worth mentioning that increasing lift effect would mean taking off from a shorter runway or allowing the airborne vehicle with the ability to fly with additional payload.
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    An Experimental Investigation of Tsunami Bore Impact on Coastal Structures
    (Mdpi, 2024) Erduran, Kutsi S.; Akansu, Yahya E.; Unal, Ugur; Adekoya, Olusola O.
    This experimental study focused on the measurement and analysis of the impact force caused by a tsunami bore on a coastal structure. The bore wave was produced by a dam break mechanism. The water depth in the reservoir and the location of the coastal structures were varied to simulate different impact scenarios. The time history of the force resulting from the impact of the bore wave on the coastal structure was measured. The propagation of the bore wave along the flume was recorded and the video recordings were converted into digital data using an image-processing technique in order to determine the flow depth variations with time. The hydrostatic forces and the corresponding depth and time-averaged hydrodynamic forces as well as the maximum hydrodynamic forces were acquired for each scenario. The ratio of hydrodynamic to hydrostatic forces were obtained, and it was observed that the calculated averaged ratio was within the recommended design ratio. The results indicate that an increase in the reservoir level caused an increase in the magnitude and intensity of the impact forces, however, the relationship was non-linear. Moreover, it was found that the location of the structure did not play a significant role on the intensity of the impact forces.
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    Influence of Leading-Edge Tubercle with Amplitude Modulation on NACA 0015 Airfoil
    (Amer Inst Aeronautics Astronautics, 2021) Seyhan, Mehmet; Sarioglu, Mustafa; Akansu, Yahya E.
    Flow around a NACA0015 airfoil with leading-edge tubercles was investigated using force measurements and flow visualization at 0 deg <= alpha <= 30 deg. The experiments were carried out at a low Reynolds number of Re = 6.3 x 10(4), where the transition to turbulent flow still occurred on the suction side of the airfoil. The leading-edge patterns of the models were produced by using only either one wave function or one superposition of two wave functions. Two tubercle models with uniform distribution and nine more realistic biomimicked airfoil models with amplitude modulation in tubercle geometry were tested in experiments. Force measurements showed that when compared to the baseline model, models with tubercles did not experience a sudden loss of lift and have higher lift coefficients in the poststall regime, irrespective of the model. It was found that the W15 model performs best in terms of maximum lift coefficient, stall angle, aerodynamic performance (C-L/C-D) in the poststall regime; as well as in terms of the minimum fluctuating lift coefficient C-L' in both pre- and poststall regimes. Enhancement of aerodynamic performance is due to the presence of stall cell formation with the counter-rotating vortex pairs and three-dimensional spanwise flow pattern initiated by leading-edge tubercles at the poststall regime.