Effects of Bypass Ratio Change Trend on Performance in a Military Aircraft Turbofan Engine With Comparative Assessment

In this study, it is aimed to observe the bypass effects on energetic and exergetic performance in a JT3D-3B Military Aircraft Turbofan Engine and its components. For this aim, the comprehensive energy and exergy analyses are performed separately at the various bypass ratios: BPR: 1.30 (Case A), BPR: 1.34 (Case B), BPR: 1.38 (Case C), BPR: 1.40 (Case D), BPR: 1.42 (Case E), BPR: 1.45 (Case F), and BPR: 1.36 (original design). As per the performance results, while the energetic efficiency of the engine is found to be 27.93% for Case F, 27.85% for Case E, 27.72% for Case D, 27.60% for Case C, 27.17% for Case B, 26.97% for Case A, the exergetic efficiency of the engine is found to be 26.23% for Case F, 26.23% for Case E, 26.11% for Case D, 26.00% for Case C, 25.59% for Case B, and 25.39% for Case A, Furthermore, with the increase of bypass ratio step by step from 1.30 to 1.45, while the energetic efficiency, the exergetic efficiency, the relative exergy consumption value tends to increase, the fuel exergy waste ratio value, the productivity lack ratio, and exergetic improvement potential value of the overall engine tends to decrease. This study can be helpful for turbofan engine users, owners, and designers.