Flow and Heat Transfer Characteristics of a Swirling Impinging Jet Issuing from a Threaded Nozzle of 45 Degrees
In order to achieve uniform and effective impingement cooling, a swirling jet with a swirling angle of 45° (SIJ 45°) is put forward in this paper. Namely, there are four 45° spiral grooves equipped on the inner wall of the circular hole. The difference in the flow field and heat transfer characteris...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-12-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/14/24/8412 |
| _version_ | 1797505023674941440 |
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| author | Liang Xu Tao Yang Yanhua Sun Lei Xi Jianmin Gao Yunlong Li |
| author_facet | Liang Xu Tao Yang Yanhua Sun Lei Xi Jianmin Gao Yunlong Li |
| author_sort | Liang Xu |
| collection | DOAJ |
| description | In order to achieve uniform and effective impingement cooling, a swirling jet with a swirling angle of 45° (SIJ 45°) is put forward in this paper. Namely, there are four 45° spiral grooves equipped on the inner wall of the circular hole. The difference in the flow field and heat transfer characteristics between the conventional impinging jet (CIJ) and SIJ <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>45</mn><mo>°</mo></mrow></semantics></math></inline-formula> is compared and analyzed. The spiral channels can increase the heat transfer rate and cooling uniformity because of the action of superimposed airflow. In addition, the thread nozzle brings lower pressure loss, which can reduce the airflow friction while effectively ensuring high heat transfer in the center area of the jet. An experimental system is built to investigate the heat transfer and flow characteristics of the impingement surface. Smoke flow visualization technology is used to explore the complex flow field of the CIJ and SIJ <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>45</mn><mo>°</mo></mrow></semantics></math></inline-formula>, and the heat transfer rate of the target surface is analyzed based on thermocouple data. When <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>6000</mn><mo>≤</mo><mi>R</mi><mi>e</mi><mo>≤</mo><mn>30,000</mn><mo>,</mo></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo>≤</mo><mi>h</mi><mo>/</mo><msub><mi>d</mi><mi>j</mi></msub><mo>≤</mo><mn>8</mn></mrow></semantics></math></inline-formula>, the averaged Nusselt number (<i>Nu</i>) correlation for SIJ 45° is established, which is in good agreement with the experimental results. SIJ 45° is an effective measure to replace the CIJ, and the research herein provides some reference for designing the structure of new jets. |
| first_indexed | 2024-03-10T04:12:45Z |
| format | Article |
| id | doaj.art-10ab24dc38cd4b48986dd5b796be93f1 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-10T04:12:45Z |
| publishDate | 2021-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-10ab24dc38cd4b48986dd5b796be93f12023-11-23T08:06:56ZengMDPI AGEnergies1996-10732021-12-011424841210.3390/en14248412Flow and Heat Transfer Characteristics of a Swirling Impinging Jet Issuing from a Threaded Nozzle of 45 DegreesLiang Xu0Tao Yang1Yanhua Sun2Lei Xi3Jianmin Gao4Yunlong Li5State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaState Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaState Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaState Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaState Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaState Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaIn order to achieve uniform and effective impingement cooling, a swirling jet with a swirling angle of 45° (SIJ 45°) is put forward in this paper. Namely, there are four 45° spiral grooves equipped on the inner wall of the circular hole. The difference in the flow field and heat transfer characteristics between the conventional impinging jet (CIJ) and SIJ <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>45</mn><mo>°</mo></mrow></semantics></math></inline-formula> is compared and analyzed. The spiral channels can increase the heat transfer rate and cooling uniformity because of the action of superimposed airflow. In addition, the thread nozzle brings lower pressure loss, which can reduce the airflow friction while effectively ensuring high heat transfer in the center area of the jet. An experimental system is built to investigate the heat transfer and flow characteristics of the impingement surface. Smoke flow visualization technology is used to explore the complex flow field of the CIJ and SIJ <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>45</mn><mo>°</mo></mrow></semantics></math></inline-formula>, and the heat transfer rate of the target surface is analyzed based on thermocouple data. When <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>6000</mn><mo>≤</mo><mi>R</mi><mi>e</mi><mo>≤</mo><mn>30,000</mn><mo>,</mo></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo>≤</mo><mi>h</mi><mo>/</mo><msub><mi>d</mi><mi>j</mi></msub><mo>≤</mo><mn>8</mn></mrow></semantics></math></inline-formula>, the averaged Nusselt number (<i>Nu</i>) correlation for SIJ 45° is established, which is in good agreement with the experimental results. SIJ 45° is an effective measure to replace the CIJ, and the research herein provides some reference for designing the structure of new jets.https://www.mdpi.com/1996-1073/14/24/8412swirling impinging jetsimpingement coolingheat transferflow field |
| spellingShingle | Liang Xu Tao Yang Yanhua Sun Lei Xi Jianmin Gao Yunlong Li Flow and Heat Transfer Characteristics of a Swirling Impinging Jet Issuing from a Threaded Nozzle of 45 Degrees Energies swirling impinging jets impingement cooling heat transfer flow field |
| title | Flow and Heat Transfer Characteristics of a Swirling Impinging Jet Issuing from a Threaded Nozzle of 45 Degrees |
| title_full | Flow and Heat Transfer Characteristics of a Swirling Impinging Jet Issuing from a Threaded Nozzle of 45 Degrees |
| title_fullStr | Flow and Heat Transfer Characteristics of a Swirling Impinging Jet Issuing from a Threaded Nozzle of 45 Degrees |
| title_full_unstemmed | Flow and Heat Transfer Characteristics of a Swirling Impinging Jet Issuing from a Threaded Nozzle of 45 Degrees |
| title_short | Flow and Heat Transfer Characteristics of a Swirling Impinging Jet Issuing from a Threaded Nozzle of 45 Degrees |
| title_sort | flow and heat transfer characteristics of a swirling impinging jet issuing from a threaded nozzle of 45 degrees |
| topic | swirling impinging jets impingement cooling heat transfer flow field |
| url | https://www.mdpi.com/1996-1073/14/24/8412 |
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