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Straight-level flight
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
Since the engine thrust is a function of engine power, in order to increase the thrust, one must increase the engine power. When the pilot deflects the engine throttle, the engine power is varied. Then the propeller/shaft rotational velocity (say, in revolutions per minute [rpm]) is varied, so the engine thrust is varied. This causes an acceleration, which eventually results in a greater speed. This simultaneously increases the aircraft drag; thus, the acceleration will be consequently decreased. This process is continued until the aircraft has a new equilibrium airspeed. Figure 6.3 (see later in the chapter) illustrates the typical variations of engine thrust and power in prop-driven engines.
Study on thermodynamic matching optimization of variable flow cooling system of diesel engine at high altitudes
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Chunhao Yang, Ruilin Liu, Yufei JIAO, Zhongjie Zhang, Guangmeng Zhou, Haojian Ding, Chenqi Lu
Compared with the original engine, after the application of variable flow cooling system, the power and torque of the diesel engine increased, and the higher the altitude was, the more obvious the increase effect was. In the low and medium speed region (n ≤ 1500 r/min), the increase effect of the power and torque of the diesel engine increased by 5.27% on average for every 1000 m rise. In the middle- and high-speed region (1500 r/min <n ≤ 2100 r/min), the increase effect of the power and torque of the diesel engine increased by 2.42% for every 1000 m. This was because that the variable flow cooling system actively reduced the fan speed and water pump speed at low speed of engine, which resulted in the reduction of its own power consumption, the decrease of the heat dissipation of the engine, and the high temperature of oil and cylinder components. This would restore the lubricating effect of the engine oil, greatly reduce the loss of friction among the components, and improve the engine power and torque, leading to a significant increase in the power performance.
Effects of the regenerator on engine performance of a rhombic drive beta type stirling engine
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Fatih Aksoy, Hamit Solmaz, Muhammed Arslan, Emre Yılmaz, Duygu İpci, Alper Calam
Figures 6 and 7 are about the engine power values measured versus the engine speed for engine with regenerator and engine without regenerator, respectively. In the experiments with regenerator and without regenerator, maximum engine powers were obtained at 5 bar charge pressure and were 1940 W at 1046 rpm and 1831 W at 1035 rpm for engine with regenerator and without regenerator, respectively. It should be noted that this study is a production of a continuing study since 2015. Previous results about the project was presented before (Aksoy et al. 2017; Karabulut et al. 2016; Solmaz et al. 2020). By considering the power level achieved in this study, it can be said that the engine performance was considerably better than the previous versions of the test engine. The maximum power of the previous version of the engine was 1.2 kW without regenerator (Aksoy et al. 2017). In addition, the maximum engine power of 1940 W obtained at such a low charge pressure of 5 bar is highest engine performance achieved at that charge pressure for a single cylinder beta type rhombic drive Stirling engine up to date. When examining Figures 6 and 7, it is shown that the engine power improves to a certain value depending on the increasing engine speed and then decreases for per charge pressures. Engine power values were affected from engine speed and engine torque. Decreasing heat exchange time and increasing friction losses due to the increasing of engine speed cause decreasing of the engine power. At the optimum charge pressure 5 bar, the engine power increases slightly due to regenerator, while the engine power increases considerably at other charge pressures. As a result, the regenerator significantly affects the performance of the engine.