Improving thermal efficiency and reducing carbon emissions are the permanent themes for internal combustion (IC) engines. In the past decades, various advanced strategies have been proposed to achieve higher efficiency and cleaner combustion with the increasingly stringent fuel economy and emission regulations. This article reviews the recent progress in the improvement of thermal efficiency of IC engines and provides a comprehensive summary of the latest research on thermal efficiency from aspects of thermodynamic cycles, gas exchange systems, advanced combustion strategies, and thermal and energy management. Meanwhile, the remaining challenges in different modules are also discussed. It shows that with the development of advanced technologies, it is highly positive to achieve 55% and even over 60% in effective thermal efficiency for IC engines. However, different technologies such as hybrid thermal cycles, variable intake systems, extreme condition combustion (manifesting low temperature, high pressure, and lean burning), and effective thermal and energy management are suggested to be closely integrated into the whole powertrains with highly developed electrification and intelligence.
This paper focuses on the studying behavior of velocity profile with the influence of different temperatures for the inner and outer annulus of can combustor. An experimental rig was designed to simulate the flow inside the annulus of can combustor. An analytical CFD tool was designed and validated with experimental data. The can combustor tested in this study is a real part collected from Hilla/Iraq gas turbine power station. The velocity profiles are investigated in six stations in the annulus region. The axial velocity and turbulence intensity are calculating with a different temperature for inner and outer annulus. From The results, the increase in temperature leads to undesirable reversible flow and large recirculation zone. It is found that high turbulent intensity leads to destroy the cooling film. The increasing temperature would increase the turbulence intensity causing a recirculation region enlargement. The results also show that the high temperature, velocity profile and the jet of air through holes. The Computational results were compared against the experimental results, and they show a very good agreement.
This paper focus on studying the behavior of velocity profile under force vibration for a different frequency (34, 48, 65 and 80 Hz) for lower annulus of Can Combustor. An experimental rig was designed at Babylon University /Iraq by the author. The Can Combustor tested in this study is real part collected from Al-Khairat/Iraq gas turbine power station. The velocity profiles are examined at three positions in the annular for lower region. The velocity in X-direction calculating with a different frequency for lower annulus. The results were shown that the increase of frequency lead to increase the velocity profile and large recirculation zone will form in some points. Since the flow is turbulent, So the slope of the velocity profile at the wall is big but when forced vibration effect is applied it becomes much greater than without vibration effect about (25%).Reynolds number increasing with praise of velocity in X-direction. Also, the increase in vibration level produces non-uniform velocity profile which affects the spreading of cooling efficiency. Finally the shape of velocity profile change from flatter to non-uniform shape due to fluctuation vibration effect so, the cooling film air fails to protect the linear wall of Combustor from damage.
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