Fluid Dynamics of Interacting Rotor Wake with a Water Surface
Rotor-type cross-media vehicles always induce considerably complex mixed air–water flows when approaching the water surface, resulting in relative thrust loss and structural damage on rotor. The interactions between a water surface and rotor wake bring potential risks to the cross-media process, whi...
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MDPI AG
2024-09-01
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| Series: | Drones |
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| Online Access: | https://www.mdpi.com/2504-446X/8/9/469 |
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| author | Xing-Zhi Bai Zhe Zhang Wen-Hua Wu Xiao Wang Qi Zhan Dai-Xian Zhang Lei Yu |
| author_facet | Xing-Zhi Bai Zhe Zhang Wen-Hua Wu Xiao Wang Qi Zhan Dai-Xian Zhang Lei Yu |
| author_sort | Xing-Zhi Bai |
| collection | DOAJ |
| description | Rotor-type cross-media vehicles always induce considerably complex mixed air–water flows when approaching the water surface, resulting in relative thrust loss and structural damage on rotor. The interactions between a water surface and rotor wake bring potential risks to the cross-media process, which is known as the near-water effect of the rotor. In this paper, experimental investigations are used to explore the fluid dynamics of the near-water effect of the rotor. Qualitative droplet observation was carried out on the 0.25 m and 0.56 m diameter commercial rotor blades and the 0.07 m diameter ducted fan near the water surface first to gain a qualitative understanding of droplet characteristics. The results show that the rotor wake caused water surface deformation, droplet tearing off, splashing, and entrainment into the rotor disk. The depression formed by the rotor downwash flow impacting the water surface is named as three modes: dimpling, splashing, and penetrating, and the correlation between the depression modes and the aerodynamic characteristics of the rotor is primary analyzed. The flow mechanisms of dimpling mode were studied using the particle image velocimetry (PIV) technique. The results showed that the cavity and liquid crown obviously alter the flow direction of water surface jets, but not all rotors near water enter the vortex ring state. Two splashing mechanisms were revealed, including the direct ejection of droplets at the rim of depression and the tearing of liquid crown by the water surface jets. The blade tip vortex in the surface jet is a potential cause of entrainment into the rotor disk and secondary breakup of the droplet. |
| format | Article |
| id | doaj-art-271e6470d8894c2abb1990da97eecaf3 |
| institution | OA Journals |
| issn | 2504-446X |
| language | English |
| publishDate | 2024-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Drones |
| spelling | doaj-art-271e6470d8894c2abb1990da97eecaf32025-08-20T01:55:30ZengMDPI AGDrones2504-446X2024-09-018946910.3390/drones8090469Fluid Dynamics of Interacting Rotor Wake with a Water SurfaceXing-Zhi Bai0Zhe Zhang1Wen-Hua Wu2Xiao Wang3Qi Zhan4Dai-Xian Zhang5Lei Yu6Key Laboratory of Cross-Domain Flight interdisciplinary Technology, China Aerodynamics Research and Development Center, Mianyang 621000, ChinaKey Laboratory of Cross-Domain Flight interdisciplinary Technology, China Aerodynamics Research and Development Center, Mianyang 621000, ChinaKey Laboratory of Cross-Domain Flight interdisciplinary Technology, China Aerodynamics Research and Development Center, Mianyang 621000, ChinaNational Key Laboratory of Helicopter Aeromechanics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, ChinaNational Key Laboratory of Helicopter Aeromechanics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, ChinaKey Laboratory of Cross-Domain Flight interdisciplinary Technology, China Aerodynamics Research and Development Center, Mianyang 621000, ChinaKey Laboratory of Cross-Domain Flight interdisciplinary Technology, China Aerodynamics Research and Development Center, Mianyang 621000, ChinaRotor-type cross-media vehicles always induce considerably complex mixed air–water flows when approaching the water surface, resulting in relative thrust loss and structural damage on rotor. The interactions between a water surface and rotor wake bring potential risks to the cross-media process, which is known as the near-water effect of the rotor. In this paper, experimental investigations are used to explore the fluid dynamics of the near-water effect of the rotor. Qualitative droplet observation was carried out on the 0.25 m and 0.56 m diameter commercial rotor blades and the 0.07 m diameter ducted fan near the water surface first to gain a qualitative understanding of droplet characteristics. The results show that the rotor wake caused water surface deformation, droplet tearing off, splashing, and entrainment into the rotor disk. The depression formed by the rotor downwash flow impacting the water surface is named as three modes: dimpling, splashing, and penetrating, and the correlation between the depression modes and the aerodynamic characteristics of the rotor is primary analyzed. The flow mechanisms of dimpling mode were studied using the particle image velocimetry (PIV) technique. The results showed that the cavity and liquid crown obviously alter the flow direction of water surface jets, but not all rotors near water enter the vortex ring state. Two splashing mechanisms were revealed, including the direct ejection of droplets at the rim of depression and the tearing of liquid crown by the water surface jets. The blade tip vortex in the surface jet is a potential cause of entrainment into the rotor disk and secondary breakup of the droplet.https://www.mdpi.com/2504-446X/8/9/469cross-media vehiclenear-water effectrotordropletswater surfaceparticle image velocimetry |
| spellingShingle | Xing-Zhi Bai Zhe Zhang Wen-Hua Wu Xiao Wang Qi Zhan Dai-Xian Zhang Lei Yu Fluid Dynamics of Interacting Rotor Wake with a Water Surface Drones cross-media vehicle near-water effect rotor droplets water surface particle image velocimetry |
| title | Fluid Dynamics of Interacting Rotor Wake with a Water Surface |
| title_full | Fluid Dynamics of Interacting Rotor Wake with a Water Surface |
| title_fullStr | Fluid Dynamics of Interacting Rotor Wake with a Water Surface |
| title_full_unstemmed | Fluid Dynamics of Interacting Rotor Wake with a Water Surface |
| title_short | Fluid Dynamics of Interacting Rotor Wake with a Water Surface |
| title_sort | fluid dynamics of interacting rotor wake with a water surface |
| topic | cross-media vehicle near-water effect rotor droplets water surface particle image velocimetry |
| url | https://www.mdpi.com/2504-446X/8/9/469 |
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