Numerical Study on Effects of Geometric Parameters on the Release Characteristics of Straight Sudden Expansion Gas Extinguishing Nozzles
In order to guide the optimization design of the nozzle of the aircraft-fixed gas fire extinguishing system, we studied the influence of nozzle geometric parameters including outlet–inlet area ratio, length–diameter aspect ratio, and wall roughness on the distribution of pressure and velocity in the...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-12-01
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| Series: | Symmetry |
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| Online Access: | https://www.mdpi.com/2073-8994/13/12/2440 |
| _version_ | 1797500283684651008 |
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| author | Quanwei Li Xiaohua He Yongbing Chen Jiang Lin Yi Zhang Ruiyu Chen Xia Zhou |
| author_facet | Quanwei Li Xiaohua He Yongbing Chen Jiang Lin Yi Zhang Ruiyu Chen Xia Zhou |
| author_sort | Quanwei Li |
| collection | DOAJ |
| description | In order to guide the optimization design of the nozzle of the aircraft-fixed gas fire extinguishing system, we studied the influence of nozzle geometric parameters including outlet–inlet area ratio, length–diameter aspect ratio, and wall roughness on the distribution of pressure and velocity in the nozzle on the basis of CFD simulations. Although the structure of the nozzle is axisymmetric, the spatial distribution of the pressure and velocity during the flow and release of gas extinguishing agent is not completely symmetric. It was found that both of the outlet–inlet area ratio (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">δ</mi></semantics></math></inline-formula>) and the length–diameter aspect ratio (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ξ</mi></semantics></math></inline-formula>) had a significant impact on the distribution characteristics of the pressure and axial velocity in the nozzle. With the increase of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">δ</mi></semantics></math></inline-formula>, the average pressure at the outlet cross-section of the nozzle decreased monotonically, while the average axial velocity at the outlet increased approximately linearly. When <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>ξ</mi><mo>≥</mo><mn>2</mn></mrow></semantics></math></inline-formula>, the uniformity of the pressure and velocity distribution at the nozzle outlet was significantly improved. Moreover, with the increase of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ξ</mi></semantics></math></inline-formula>, the average pressure and the average axial velocity of the outlet both showed a non-monotonic change trend, and the optimal value of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ξ</mi></semantics></math></inline-formula> should be about 3.0. Compared with <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">δ</mi></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ξ</mi></semantics></math></inline-formula>, the influence of the nozzle wall roughness (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>ε</mi><mi>N</mi></msub><mo stretchy="false">)</mo></mrow></semantics></math></inline-formula> on the flow and release characteristics of the extinguishing agent was weak. With the increase of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>ε</mi><mi>N</mi></msub></mrow></semantics></math></inline-formula>, the average pressure of the nozzle outlet increased slightly, while the average axial velocity at the nozzle outlet decreased slightly. |
| first_indexed | 2024-03-10T03:59:41Z |
| format | Article |
| id | doaj.art-2391b66ce2374d39a112dca05f85e536 |
| institution | Directory Open Access Journal |
| issn | 2073-8994 |
| language | English |
| last_indexed | 2024-03-10T03:59:41Z |
| publishDate | 2021-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Symmetry |
| spelling | doaj.art-2391b66ce2374d39a112dca05f85e5362023-11-23T10:47:16ZengMDPI AGSymmetry2073-89942021-12-011312244010.3390/sym13122440Numerical Study on Effects of Geometric Parameters on the Release Characteristics of Straight Sudden Expansion Gas Extinguishing NozzlesQuanwei Li0Xiaohua He1Yongbing Chen2Jiang Lin3Yi Zhang4Ruiyu Chen5Xia Zhou6School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, ChinaShanghai Space Propulsion Technology Research Institute, Huzhou 313000, ChinaShanghai Space Propulsion Technology Research Institute, Huzhou 313000, ChinaSchool of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, ChinaSchool of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, ChinaSchool of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, ChinaSchool of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, ChinaIn order to guide the optimization design of the nozzle of the aircraft-fixed gas fire extinguishing system, we studied the influence of nozzle geometric parameters including outlet–inlet area ratio, length–diameter aspect ratio, and wall roughness on the distribution of pressure and velocity in the nozzle on the basis of CFD simulations. Although the structure of the nozzle is axisymmetric, the spatial distribution of the pressure and velocity during the flow and release of gas extinguishing agent is not completely symmetric. It was found that both of the outlet–inlet area ratio (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">δ</mi></semantics></math></inline-formula>) and the length–diameter aspect ratio (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ξ</mi></semantics></math></inline-formula>) had a significant impact on the distribution characteristics of the pressure and axial velocity in the nozzle. With the increase of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">δ</mi></semantics></math></inline-formula>, the average pressure at the outlet cross-section of the nozzle decreased monotonically, while the average axial velocity at the outlet increased approximately linearly. When <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>ξ</mi><mo>≥</mo><mn>2</mn></mrow></semantics></math></inline-formula>, the uniformity of the pressure and velocity distribution at the nozzle outlet was significantly improved. Moreover, with the increase of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ξ</mi></semantics></math></inline-formula>, the average pressure and the average axial velocity of the outlet both showed a non-monotonic change trend, and the optimal value of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ξ</mi></semantics></math></inline-formula> should be about 3.0. Compared with <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">δ</mi></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ξ</mi></semantics></math></inline-formula>, the influence of the nozzle wall roughness (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>ε</mi><mi>N</mi></msub><mo stretchy="false">)</mo></mrow></semantics></math></inline-formula> on the flow and release characteristics of the extinguishing agent was weak. With the increase of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>ε</mi><mi>N</mi></msub></mrow></semantics></math></inline-formula>, the average pressure of the nozzle outlet increased slightly, while the average axial velocity at the nozzle outlet decreased slightly.https://www.mdpi.com/2073-8994/13/12/2440aircraft fire extinguishing systemstraight sudden expansion nozzlegas–liquid two-phase flowgas extinguishing agentpressure and velocity distribution |
| spellingShingle | Quanwei Li Xiaohua He Yongbing Chen Jiang Lin Yi Zhang Ruiyu Chen Xia Zhou Numerical Study on Effects of Geometric Parameters on the Release Characteristics of Straight Sudden Expansion Gas Extinguishing Nozzles Symmetry aircraft fire extinguishing system straight sudden expansion nozzle gas–liquid two-phase flow gas extinguishing agent pressure and velocity distribution |
| title | Numerical Study on Effects of Geometric Parameters on the Release Characteristics of Straight Sudden Expansion Gas Extinguishing Nozzles |
| title_full | Numerical Study on Effects of Geometric Parameters on the Release Characteristics of Straight Sudden Expansion Gas Extinguishing Nozzles |
| title_fullStr | Numerical Study on Effects of Geometric Parameters on the Release Characteristics of Straight Sudden Expansion Gas Extinguishing Nozzles |
| title_full_unstemmed | Numerical Study on Effects of Geometric Parameters on the Release Characteristics of Straight Sudden Expansion Gas Extinguishing Nozzles |
| title_short | Numerical Study on Effects of Geometric Parameters on the Release Characteristics of Straight Sudden Expansion Gas Extinguishing Nozzles |
| title_sort | numerical study on effects of geometric parameters on the release characteristics of straight sudden expansion gas extinguishing nozzles |
| topic | aircraft fire extinguishing system straight sudden expansion nozzle gas–liquid two-phase flow gas extinguishing agent pressure and velocity distribution |
| url | https://www.mdpi.com/2073-8994/13/12/2440 |
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