Investigation on Jet Characteristics of Turbofan Exhaust System under Take-off Condition with High Angle of Attack
To understand the jet flow characteristics of turbofan separate exhaust system, a parametric design method based on the initial Class Shape Transformation function was developed. HBPR and UHBPR turbofan separate exhaust systems were designed. Furthermore, the jet flow characteristics of the HBPR tur...
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| Format: | Article |
| Language: | English |
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Isfahan University of Technology
2022-03-01
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| Series: | Journal of Applied Fluid Mechanics |
| Subjects: | |
| Online Access: | https://www.jafmonline.net/article_2041_9dcf149579813b7376f3fcf42da4ba6c.pdf |
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| author | Z. X. Wang W. J. Wang L. Zhou W. J. Deng J. W. Shi |
| author_facet | Z. X. Wang W. J. Wang L. Zhou W. J. Deng J. W. Shi |
| author_sort | Z. X. Wang |
| collection | DOAJ |
| description | To understand the jet flow characteristics of turbofan separate exhaust system, a parametric design method based on the initial Class Shape Transformation function was developed. HBPR and UHBPR turbofan separate exhaust systems were designed. Furthermore, the jet flow characteristics of the HBPR turbofan exhaust system under take-off condition with zero angle of attack were studied based on numerical simulation. The jet flow characteristics of the HBPR and UHBPR turbofan exhaust system under take-off condition with high angle of attack were also simulated. The effects of angle of attack and bypass ratio on the jet flow characteristics were investigated and the related flow mechanisms were analyzed. Results show that the axisymmetric plumes of the HBPR turbofan exhaust system are distributed around the engine axis under take-off condition with zero angle of attack. With the plug wake as the center, the core flow, the fan/core shear layer, the fan flow, the fan/free stream shear layer and the free stream are wrapped around the plug wake from inside out. Vortexes appear in the lee area at the back of the cowl and jet flow under take-off condition with high angle of attack. These vortexes cause cross sectional secondary flow and expose the high-velocity core flow to the low-velocity free stream. The contact area and velocity gradient in the mixing region among the free stream, fan flow and core flow increase. Therefore, the mixture among jet flow and free stream strengthens. So the high-velocity region, the high-vorticity region, and the high turbulence kinetic energy region shorten by 55.1%, 47.7% and 50.9% respectively. The vorticity values and turbulence kinetic energy level peak on the upper side of the exhaust plumes increase by about 30% and 87% respectively. Relative to these parameters from the HBPR turbofan exhaust system, the jet velocity peak value of UHBPR turbofan decreases by 5.5% under take-off condition with high angle of attack. The vorticity values and turbulence kinetic energy level reduce due to decreased velocity gradient in shear layers downstream of the nozzle exit plane. The turbulence kinetic energy level peak on the upper side of the exhaust plumes decreases by 29.3%. The reasons are that the contact area between high-velocity core flow and the free stream decreases due to thicker fan flow and the velocity gradient in the core flow and free stream mixing region decreases because of the lower core flow velocity. |
| first_indexed | 2024-04-13T16:30:40Z |
| format | Article |
| id | doaj.art-7a98310f82f443b79acf2dc1a6ee1239 |
| institution | Directory Open Access Journal |
| issn | 1735-3572 1735-3645 |
| language | English |
| last_indexed | 2024-04-13T16:30:40Z |
| publishDate | 2022-03-01 |
| publisher | Isfahan University of Technology |
| record_format | Article |
| series | Journal of Applied Fluid Mechanics |
| spelling | doaj.art-7a98310f82f443b79acf2dc1a6ee12392022-12-22T02:39:35ZengIsfahan University of TechnologyJournal of Applied Fluid Mechanics1735-35721735-36452022-03-0115394395810.47176/jafm.15.03.333642041Investigation on Jet Characteristics of Turbofan Exhaust System under Take-off Condition with High Angle of AttackZ. X. Wang0W. J. Wang1L. Zhou2W. J. Deng3J. W. Shi4Shaanxi Key Laboratory of Internal Aerodynamics in Aero-Engine, School of Power and Energy, Northwestern Polytechnical University, Xi’an, 710072, People’s Republic of ChinaShaanxi Key Laboratory of Internal Aerodynamics in Aero-Engine, School of Power and Energy, Northwestern Polytechnical University, Xi’an, 710072, People’s Republic of ChinaShaanxi Key Laboratory of Internal Aerodynamics in Aero-Engine, School of Power and Energy, Northwestern Polytechnical University, Xi’an, 710072, People’s Republic of ChinaShaanxi Key Laboratory of Internal Aerodynamics in Aero-Engine, School of Power and Energy, Northwestern Polytechnical University, Xi’an, 710072, People’s Republic of ChinaShaanxi Key Laboratory of Internal Aerodynamics in Aero-Engine, School of Power and Energy, Northwestern Polytechnical University, Xi’an, 710072, People’s Republic of ChinaTo understand the jet flow characteristics of turbofan separate exhaust system, a parametric design method based on the initial Class Shape Transformation function was developed. HBPR and UHBPR turbofan separate exhaust systems were designed. Furthermore, the jet flow characteristics of the HBPR turbofan exhaust system under take-off condition with zero angle of attack were studied based on numerical simulation. The jet flow characteristics of the HBPR and UHBPR turbofan exhaust system under take-off condition with high angle of attack were also simulated. The effects of angle of attack and bypass ratio on the jet flow characteristics were investigated and the related flow mechanisms were analyzed. Results show that the axisymmetric plumes of the HBPR turbofan exhaust system are distributed around the engine axis under take-off condition with zero angle of attack. With the plug wake as the center, the core flow, the fan/core shear layer, the fan flow, the fan/free stream shear layer and the free stream are wrapped around the plug wake from inside out. Vortexes appear in the lee area at the back of the cowl and jet flow under take-off condition with high angle of attack. These vortexes cause cross sectional secondary flow and expose the high-velocity core flow to the low-velocity free stream. The contact area and velocity gradient in the mixing region among the free stream, fan flow and core flow increase. Therefore, the mixture among jet flow and free stream strengthens. So the high-velocity region, the high-vorticity region, and the high turbulence kinetic energy region shorten by 55.1%, 47.7% and 50.9% respectively. The vorticity values and turbulence kinetic energy level peak on the upper side of the exhaust plumes increase by about 30% and 87% respectively. Relative to these parameters from the HBPR turbofan exhaust system, the jet velocity peak value of UHBPR turbofan decreases by 5.5% under take-off condition with high angle of attack. The vorticity values and turbulence kinetic energy level reduce due to decreased velocity gradient in shear layers downstream of the nozzle exit plane. The turbulence kinetic energy level peak on the upper side of the exhaust plumes decreases by 29.3%. The reasons are that the contact area between high-velocity core flow and the free stream decreases due to thicker fan flow and the velocity gradient in the core flow and free stream mixing region decreases because of the lower core flow velocity.https://www.jafmonline.net/article_2041_9dcf149579813b7376f3fcf42da4ba6c.pdfjet characteristicsexhaust systemtake-off conditionhigh angle of attackturbofan |
| spellingShingle | Z. X. Wang W. J. Wang L. Zhou W. J. Deng J. W. Shi Investigation on Jet Characteristics of Turbofan Exhaust System under Take-off Condition with High Angle of Attack Journal of Applied Fluid Mechanics jet characteristics exhaust system take-off condition high angle of attack turbofan |
| title | Investigation on Jet Characteristics of Turbofan Exhaust System under Take-off Condition with High Angle of Attack |
| title_full | Investigation on Jet Characteristics of Turbofan Exhaust System under Take-off Condition with High Angle of Attack |
| title_fullStr | Investigation on Jet Characteristics of Turbofan Exhaust System under Take-off Condition with High Angle of Attack |
| title_full_unstemmed | Investigation on Jet Characteristics of Turbofan Exhaust System under Take-off Condition with High Angle of Attack |
| title_short | Investigation on Jet Characteristics of Turbofan Exhaust System under Take-off Condition with High Angle of Attack |
| title_sort | investigation on jet characteristics of turbofan exhaust system under take off condition with high angle of attack |
| topic | jet characteristics exhaust system take-off condition high angle of attack turbofan |
| url | https://www.jafmonline.net/article_2041_9dcf149579813b7376f3fcf42da4ba6c.pdf |
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