| 1. |
- Li, Yong, et al.
(författare)
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竖直矩形通道内超临界正癸烷振荡特性的大涡模拟
- 2022
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Ingår i: Nanjing Hangkong Hangtian Daxue Xuebao/Journal of Nanjing University of Aeronautics and Astronautics. - 1005-2615. ; 54:2, s. 281-289
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Tidskriftsartikel (refereegranskat)abstract
- Active generative cooling based on supercritical hydrocarbon fuel is regarded as one of the most promising methods for scramjet thermal management. A large eddy simulation method is used to explore the transient change law of the initial flow, and heat transfer behaviors of supercritical hydrocarbon fuel is in rectangular channels. An oscillation effect can be proved in the convective heat transfer process, i.e., the temperature and velocity distributions fluctuate strongly. By monitoring the velocity variation rule of 10-4 s time scale, the approximate trigonometric frequency and amplitude are present in this oscillation. At the initial heating condition, the high-temperature fluid, which is close to the heated wall, flows into the low-temperature region under the effect of buoyancy force. As the fluid temperature gradually reaches the pseudo-critical value, its thermo-physical properties change dramatically. The friction factor oscillates as well as the fluid kinetic energy. Correspondingly, the enhanced vortex is induced away from the heated wall. Over time, the enhanced vortex begins to move to the heated wall and the low-temperature fluid impinges on the wall. Consequently, the thermal transport is enhanced.
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| 2. |
- Zhang, Guohua, et al.
(författare)
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截断肋排布方式对内冷通道换热性能的影响
- 2021
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Ingår i: Nanjing Hangkong Hangtian Daxue Xuebao/Journal of Nanjing University of Aeronautics and Astronautics. - 1005-2615. ; 53:4, s. 504-512
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Tidskriftsartikel (refereegranskat)abstract
- Experimental studies are carried out to investigate the heat transfer performance of six different arrangements of truncated ribs in internal cooling channel by fixing the Reynolds number. The convective heat transfer mechanisms of the considered cases are detailed and analyzed based on the fluid flow characteristics by using three dimensional numerical simulations. The results show that among six different arrangements of truncated ribs, Case 2-3-5-9 possesses the best heat transfer performance while Case 2-5-3-9 has the worst heat transfer performance. However, the pressure drop for Case 2-3-5-9 is the largest while it is the lowest for Case 2-5-9-3. In terms of overall thermal performance, Case 2-9-5-3 performs the best, followed by Case 2-3-5-9, and Case 2-5-3-9 performs the worst. Through analyzing the flow characteristics of different cases, it is found that the transverse vortices induced by the truncated regions in the truncated ribbed channel can result in strong flow mixing between the mainstream and boundary flow, which can enhance the heat transfer performance in the channel. In addition, different arrangements of truncated ribs lead to different flow characteristics in the internal cooling channels, but the vortices induced by the truncated regions look similar.
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