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    Öğe
    Effect of Contamination in Cooling Water Line on Emissions and Equipment of Vessels
    (2022) Süner, Münir; Yıldız, Tankut
    Emission is a threat to all living things. Despite all the conferences on climate change, emissions could not be reduced. On the contrary, its effect continues to increase. Ships use fossil-based energy and they are widely used vehicles in transportation. This paper provides an analysis of emission in ship main engine and auxiliary machinery. In addition, the effect of contamination on safety valve of ship and funnel is illustrated clearly. All data used in this study were taken from the ship during the 79-day cruise. When the pollution factor was eliminated, the average NOx and SOx and total emissions from the cylinder jackets, seawater circuit, scavenger circuit, freshwater circuit decreased significantly. The average revolution of main engine increased by 20% after cleaning. The results of vibration due to contamination were found to be collapse and broke up of the cylinder safety valve of main engine, and insulation layer of funnel of ship was collapsed. Only due to the contamination of the jackets and cylinders of main engine, the amount of energy losses before the ship goes aground increased by 37.48%. But this decreased by 20.83% just after the cleaning procedures were carried out. In addition, the sea circuit of main engine was contaminated at different rates on ship simulator. The actual data is in consistence with the data obtained from the ship simulator.
  • [ X ]
    Öğe
    The effect of bifurcation angulation on flow characteristics and hemodynamic indicators in an idealized left coronary artery
    (Elsevier B.V., 2024) Müftüoğulları, Ali; Süner, Münir; Sarper, Buğra
    Atherosclerosis is a pathological condition characterized by inflammation in the main arteries, which serves as the primary factor for the development of cardiovascular disease. This condition represents the prevailing medical and surgical issue. Clinically, consequences of this condition might include stroke, coronary artery and heart disease, or peripheral vascular disease. In this study, the hemodynamic effect of three different angulations is numerically analyzed on left coronary artery and constant degree of stenosis (DoS) which equals to 50 % is implemented on each branch of three models to create stenotic arteries. The idealized left main coronary artery (LM) is modeled with its primary branches, namely left anterior descending (LAD) and left circumflex (LCx). The bifurcation angulations between LAD and LCx are considered 30°, 75° and 120°. All numerical analyses are carried out in transient regime, blood is considered as a non-Newtonian fluid and the Carreau viscosity model is selected to describe the viscosity variation of blood. The outcomes of all numerical analyses revealed that the blood flow across the branches is closely related to bifurcation angle. Recirculation is vital in the post-stenotic regions of LAD and LCx, and velocity enhances its breadth. WSS is highest in the stenosis and carina regions. OSI values are greater in the post-stenotic LAD and LCx regions where recirculation and plaque development are more likely. Helical flow appears in the post-stenotic region of the LM when velocity is lowest and in the stenotic area when velocity is highest. © 2023 The Author(s)