Investigating the Impact of Back Cavity Filling and Axial Clearance on the Flow Physics and Performance of a Pump as Turbine
The Pumps as Turbines (PAT) is a well-established technology suitable for standalone micro-hydropower plants and energy recovery systems. But being lower performance than the dedicated turbines, there are continuous efforts to improve it keeping cost benefits intact. One of the recent modifications...
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| Format: | Article |
| Language: | English |
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Isfahan University of Technology
2024-01-01
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| Series: | Journal of Applied Fluid Mechanics |
| Subjects: | |
| Online Access: | https://www.jafmonline.net/article_2387_9c4019c8763e9a38ae3c00bba4c382d7.pdf |
| _version_ | 1797338096282370048 |
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| author | R. Gaji A. Doshi M. Bade |
| author_facet | R. Gaji A. Doshi M. Bade |
| author_sort | R. Gaji |
| collection | DOAJ |
| description | The Pumps as Turbines (PAT) is a well-established technology suitable for standalone micro-hydropower plants and energy recovery systems. But being lower performance than the dedicated turbines, there are continuous efforts to improve it keeping cost benefits intact. One of the recent modifications of the back cavity filling plays a crucial role in the performance of PAT which is not investigated in detail. In the present paper, the PAT back cavity is filled with a solid ring of various sizes and shapes (back cavity filling) to explore its impact. The developed test facility is used to validate the experimental results with the numerical results for the base case. A numerical model after validation has been employed to investigate the impact of back cavity filling on the internal flow dynamics and the PAT performance. Additionally, the study explored the influence of axial clearance on flow physics, associated losses, and the PAT performance, an aspect rarely discussed by researchers in the PAT mode. After back cavity filling, secondary flow-based disk friction losses were reduced, leading to a 3.5 % increase in PAT efficiency. An analysis of the axial clearance showed that increasing it from 0.015 to 0.076 (mean axial gap/impeller radius) led to a 2.6 % reduction in PAT efficiency. This decline can be primarily attributed to elevated losses associated with disk friction, increased volumetric losses, and the formation of a mixing zone at the impeller inlet, which impeded the flow into the impeller's flow zone. |
| first_indexed | 2024-03-08T09:26:07Z |
| format | Article |
| id | doaj.art-9357be111dff4144b579c67e3bd0918f |
| institution | Directory Open Access Journal |
| issn | 1735-3572 1735-3645 |
| language | English |
| last_indexed | 2024-03-08T09:26:07Z |
| publishDate | 2024-01-01 |
| publisher | Isfahan University of Technology |
| record_format | Article |
| series | Journal of Applied Fluid Mechanics |
| spelling | doaj.art-9357be111dff4144b579c67e3bd0918f2024-01-31T09:46:43ZengIsfahan University of TechnologyJournal of Applied Fluid Mechanics1735-35721735-36452024-01-0117479981510.47176/jafm.17.4.22562387Investigating the Impact of Back Cavity Filling and Axial Clearance on the Flow Physics and Performance of a Pump as TurbineR. Gaji0A. Doshi1M. Bade2Sardar Vallabhbhai National Institute of Technology, Surat 395007, India /Annasaheb Dange College of Engineering and Technology, Ashta 416301, IndiaSardar Vallabhbhai National Institute of Technology, Surat 395007, IndiaSardar Vallabhbhai National Institute of Technology, Surat 395007, IndiaThe Pumps as Turbines (PAT) is a well-established technology suitable for standalone micro-hydropower plants and energy recovery systems. But being lower performance than the dedicated turbines, there are continuous efforts to improve it keeping cost benefits intact. One of the recent modifications of the back cavity filling plays a crucial role in the performance of PAT which is not investigated in detail. In the present paper, the PAT back cavity is filled with a solid ring of various sizes and shapes (back cavity filling) to explore its impact. The developed test facility is used to validate the experimental results with the numerical results for the base case. A numerical model after validation has been employed to investigate the impact of back cavity filling on the internal flow dynamics and the PAT performance. Additionally, the study explored the influence of axial clearance on flow physics, associated losses, and the PAT performance, an aspect rarely discussed by researchers in the PAT mode. After back cavity filling, secondary flow-based disk friction losses were reduced, leading to a 3.5 % increase in PAT efficiency. An analysis of the axial clearance showed that increasing it from 0.015 to 0.076 (mean axial gap/impeller radius) led to a 2.6 % reduction in PAT efficiency. This decline can be primarily attributed to elevated losses associated with disk friction, increased volumetric losses, and the formation of a mixing zone at the impeller inlet, which impeded the flow into the impeller's flow zone.https://www.jafmonline.net/article_2387_9c4019c8763e9a38ae3c00bba4c382d7.pdfback cavity fillinginternal hydraulicsperformancewakedisk friction lossesmixing zone |
| spellingShingle | R. Gaji A. Doshi M. Bade Investigating the Impact of Back Cavity Filling and Axial Clearance on the Flow Physics and Performance of a Pump as Turbine Journal of Applied Fluid Mechanics back cavity filling internal hydraulics performance wake disk friction losses mixing zone |
| title | Investigating the Impact of Back Cavity Filling and Axial Clearance on the Flow Physics and Performance of a Pump as Turbine |
| title_full | Investigating the Impact of Back Cavity Filling and Axial Clearance on the Flow Physics and Performance of a Pump as Turbine |
| title_fullStr | Investigating the Impact of Back Cavity Filling and Axial Clearance on the Flow Physics and Performance of a Pump as Turbine |
| title_full_unstemmed | Investigating the Impact of Back Cavity Filling and Axial Clearance on the Flow Physics and Performance of a Pump as Turbine |
| title_short | Investigating the Impact of Back Cavity Filling and Axial Clearance on the Flow Physics and Performance of a Pump as Turbine |
| title_sort | investigating the impact of back cavity filling and axial clearance on the flow physics and performance of a pump as turbine |
| topic | back cavity filling internal hydraulics performance wake disk friction losses mixing zone |
| url | https://www.jafmonline.net/article_2387_9c4019c8763e9a38ae3c00bba4c382d7.pdf |
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