Numerical Study on the Influence of Water Depth on Air Layer Drag Reduction
Over the years, air lubrication technology has been widely applied to maritime vessels, demonstrating its significant energy-saving and emission-reducing effects. However, the application of this technology in inland waterway transportation faces unique challenges due to the shallower water depths,...
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MDPI AG
2024-01-01
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| author | Qing Ye Yongpeng Ou Guo Xiang Junjie Chen |
| author_facet | Qing Ye Yongpeng Ou Guo Xiang Junjie Chen |
| author_sort | Qing Ye |
| collection | DOAJ |
| description | Over the years, air lubrication technology has been widely applied to maritime vessels, demonstrating its significant energy-saving and emission-reducing effects. However, the application of this technology in inland waterway transportation faces unique challenges due to the shallower water depths, particularly during low water periods. Under such conditions, the formation of the air layer and its associated drag-reduction effects may undergo alterations. Conducting research on air lubrication technology in shallow water conditions holds great practical significance for promoting its application in inland waterway vessels. Therefore, a numerical study is undertaken to examine the impact of water depth on Air layer Drag Reduction (ALDR) to promote the use of ALDR technology on inland canal boats with shallow water depths. The object was a specific river-sea direct ship model, and a groove was created at the bottom of the model with air injection. At two distinct speeds, numerical simulations were run for four different depths: deep water, moderate water, shallow water, and ultra-shallow water. A comparative examination of the air layer morphology on the ship bottom and drag reduction was conducted to investigate the impact of water depth on ALDR and confirm the viability of using ALDR technology on shallow-water navigation boats. The results indicate that due to the change in the velocity and pressure fields at the bottom of the ship, the efficiency of drag reduction and the form of the air layer on the ship’s bottom are significantly impacted by variations in water depth in restricted waters. However, the total resistance can still be significantly reduced by setting grooves on the hull with air injected in shallow waterways. Reduced frictional resistance no longer predominates the overall resistance reduction in shallow water; the proportion of the decrease in viscous pressure resistance rises and can reach up to 4.8 times the decrease in frictional resistance. The research confirms the application prospects of this technology on inland waterway transport ships. |
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| language | English |
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| spelling | doaj.art-c0c385691cd74ac3a47399f87e374d9a2024-01-10T14:52:07ZengMDPI AGApplied Sciences2076-34172024-01-0114143110.3390/app14010431Numerical Study on the Influence of Water Depth on Air Layer Drag ReductionQing Ye0Yongpeng Ou1Guo Xiang2Junjie Chen3Department of Naval Architecture, Naval University of Engineering, Wuhan 430033, ChinaDepartment of Naval Architecture, Naval University of Engineering, Wuhan 430033, ChinaDepartment of Naval Architecture, Naval University of Engineering, Wuhan 430033, ChinaDepartment of Naval Architecture, Naval University of Engineering, Wuhan 430033, ChinaOver the years, air lubrication technology has been widely applied to maritime vessels, demonstrating its significant energy-saving and emission-reducing effects. However, the application of this technology in inland waterway transportation faces unique challenges due to the shallower water depths, particularly during low water periods. Under such conditions, the formation of the air layer and its associated drag-reduction effects may undergo alterations. Conducting research on air lubrication technology in shallow water conditions holds great practical significance for promoting its application in inland waterway vessels. Therefore, a numerical study is undertaken to examine the impact of water depth on Air layer Drag Reduction (ALDR) to promote the use of ALDR technology on inland canal boats with shallow water depths. The object was a specific river-sea direct ship model, and a groove was created at the bottom of the model with air injection. At two distinct speeds, numerical simulations were run for four different depths: deep water, moderate water, shallow water, and ultra-shallow water. A comparative examination of the air layer morphology on the ship bottom and drag reduction was conducted to investigate the impact of water depth on ALDR and confirm the viability of using ALDR technology on shallow-water navigation boats. The results indicate that due to the change in the velocity and pressure fields at the bottom of the ship, the efficiency of drag reduction and the form of the air layer on the ship’s bottom are significantly impacted by variations in water depth in restricted waters. However, the total resistance can still be significantly reduced by setting grooves on the hull with air injected in shallow waterways. Reduced frictional resistance no longer predominates the overall resistance reduction in shallow water; the proportion of the decrease in viscous pressure resistance rises and can reach up to 4.8 times the decrease in frictional resistance. The research confirms the application prospects of this technology on inland waterway transport ships.https://www.mdpi.com/2076-3417/14/1/431air lubricationair layer drag reductionshallow waterair layer morphologycomputational fluid dynamicsfull-formed ship |
| spellingShingle | Qing Ye Yongpeng Ou Guo Xiang Junjie Chen Numerical Study on the Influence of Water Depth on Air Layer Drag Reduction Applied Sciences air lubrication air layer drag reduction shallow water air layer morphology computational fluid dynamics full-formed ship |
| title | Numerical Study on the Influence of Water Depth on Air Layer Drag Reduction |
| title_full | Numerical Study on the Influence of Water Depth on Air Layer Drag Reduction |
| title_fullStr | Numerical Study on the Influence of Water Depth on Air Layer Drag Reduction |
| title_full_unstemmed | Numerical Study on the Influence of Water Depth on Air Layer Drag Reduction |
| title_short | Numerical Study on the Influence of Water Depth on Air Layer Drag Reduction |
| title_sort | numerical study on the influence of water depth on air layer drag reduction |
| topic | air lubrication air layer drag reduction shallow water air layer morphology computational fluid dynamics full-formed ship |
| url | https://www.mdpi.com/2076-3417/14/1/431 |
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