Effects of Surface Roughness on Windage Loss and Flow Characteristics in Shaft-Type Gap with Critical CO<sub>2</sub>
To investigate the effects of surface roughness on windage loss and flow characteristics in a shaft-type gap, the skin friction coefficient (<i>C</i><sub>f</sub>) and flow versus Reynolds number (<i>Re</i>) at different surface roughness (<i>Ra</i>) an...
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MDPI AG
2022-12-01
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| Series: | Applied Sciences |
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| Online Access: | https://www.mdpi.com/2076-3417/12/24/12631 |
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| author | Lehao Hu Qinghua Deng Zhouyang Liu Jun Li Zhenping Feng |
| author_facet | Lehao Hu Qinghua Deng Zhouyang Liu Jun Li Zhenping Feng |
| author_sort | Lehao Hu |
| collection | DOAJ |
| description | To investigate the effects of surface roughness on windage loss and flow characteristics in a shaft-type gap, the skin friction coefficient (<i>C</i><sub>f</sub>) and flow versus Reynolds number (<i>Re</i>) at different surface roughness (<i>Ra</i>) and radius ratio (<i>η</i>) values were investigated. The results showed that <i>C</i><sub>f</sub> decreased as <i>Re</i> increased, and the rate of decrease was constant at low <i>Re</i> but reduced at high <i>Re</i>. The growing relative deviations between the coefficients of smooth and rough walls with <i>Ra</i> indicated that <i>C</i><sub>f</sub> was influenced by rough walls when <i>Re</i> > 10<sup>2</sup>. Moreover, <i>C</i><sub>f</sub> and the variation rate increased with <i>η</i> and were easily influenced by <i>Ra</i> for larger <i>η</i> at low <i>Re</i>, since the interaction between wall roughness and fluid influences windage loss. In addition, the flow field implied the flow had transitioned to Taylor-Couette flow, Taylor vortexes occurred when <i>Re</i> > 10<sup>2</sup>, and the number of vortexes increased with increasing <i>Ra</i> and were reduced with increasing <i>η</i>. The velocity was divided into three regions and the pressure rose from the rotational to stationary walls, but decreased with growing <i>η</i> as a whole. This paper improves the research exploring windage loss and will help design smaller supercritical CO<sub>2</sub> power devices. |
| first_indexed | 2024-03-09T17:22:43Z |
| format | Article |
| id | doaj.art-0d04f9354cf24784b4779d2d1be22551 |
| institution | Directory Open Access Journal |
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| last_indexed | 2024-03-09T17:22:43Z |
| publishDate | 2022-12-01 |
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| series | Applied Sciences |
| spelling | doaj.art-0d04f9354cf24784b4779d2d1be225512023-11-24T13:01:58ZengMDPI AGApplied Sciences2076-34172022-12-0112241263110.3390/app122412631Effects of Surface Roughness on Windage Loss and Flow Characteristics in Shaft-Type Gap with Critical CO<sub>2</sub>Lehao Hu0Qinghua Deng1Zhouyang Liu2Jun Li3Zhenping Feng4Shaanxi Engineering Laboratory of Turbomachinery and Power Equipment, Institute of Turbomachinery, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaShaanxi Engineering Laboratory of Turbomachinery and Power Equipment, Institute of Turbomachinery, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaShaanxi Engineering Laboratory of Turbomachinery and Power Equipment, Institute of Turbomachinery, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaShaanxi Engineering Laboratory of Turbomachinery and Power Equipment, Institute of Turbomachinery, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaShaanxi Engineering Laboratory of Turbomachinery and Power Equipment, Institute of Turbomachinery, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaTo investigate the effects of surface roughness on windage loss and flow characteristics in a shaft-type gap, the skin friction coefficient (<i>C</i><sub>f</sub>) and flow versus Reynolds number (<i>Re</i>) at different surface roughness (<i>Ra</i>) and radius ratio (<i>η</i>) values were investigated. The results showed that <i>C</i><sub>f</sub> decreased as <i>Re</i> increased, and the rate of decrease was constant at low <i>Re</i> but reduced at high <i>Re</i>. The growing relative deviations between the coefficients of smooth and rough walls with <i>Ra</i> indicated that <i>C</i><sub>f</sub> was influenced by rough walls when <i>Re</i> > 10<sup>2</sup>. Moreover, <i>C</i><sub>f</sub> and the variation rate increased with <i>η</i> and were easily influenced by <i>Ra</i> for larger <i>η</i> at low <i>Re</i>, since the interaction between wall roughness and fluid influences windage loss. In addition, the flow field implied the flow had transitioned to Taylor-Couette flow, Taylor vortexes occurred when <i>Re</i> > 10<sup>2</sup>, and the number of vortexes increased with increasing <i>Ra</i> and were reduced with increasing <i>η</i>. The velocity was divided into three regions and the pressure rose from the rotational to stationary walls, but decreased with growing <i>η</i> as a whole. This paper improves the research exploring windage loss and will help design smaller supercritical CO<sub>2</sub> power devices.https://www.mdpi.com/2076-3417/12/24/12631windage lossskin friction coefficientTaylor vortexsurface roughness |
| spellingShingle | Lehao Hu Qinghua Deng Zhouyang Liu Jun Li Zhenping Feng Effects of Surface Roughness on Windage Loss and Flow Characteristics in Shaft-Type Gap with Critical CO<sub>2</sub> Applied Sciences windage loss skin friction coefficient Taylor vortex surface roughness |
| title | Effects of Surface Roughness on Windage Loss and Flow Characteristics in Shaft-Type Gap with Critical CO<sub>2</sub> |
| title_full | Effects of Surface Roughness on Windage Loss and Flow Characteristics in Shaft-Type Gap with Critical CO<sub>2</sub> |
| title_fullStr | Effects of Surface Roughness on Windage Loss and Flow Characteristics in Shaft-Type Gap with Critical CO<sub>2</sub> |
| title_full_unstemmed | Effects of Surface Roughness on Windage Loss and Flow Characteristics in Shaft-Type Gap with Critical CO<sub>2</sub> |
| title_short | Effects of Surface Roughness on Windage Loss and Flow Characteristics in Shaft-Type Gap with Critical CO<sub>2</sub> |
| title_sort | effects of surface roughness on windage loss and flow characteristics in shaft type gap with critical co sub 2 sub |
| topic | windage loss skin friction coefficient Taylor vortex surface roughness |
| url | https://www.mdpi.com/2076-3417/12/24/12631 |
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