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RISS 인기검색어
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- 저자 : Dazhong Lao (검색결과 2 건)
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Internal flow characteristics of a variable mixed flow turbine with partially-rotating vane nozzle
Hanzhi Zhang,Dazhong Lao,Ce Yang,Dengfeng Yang,Xiaoxiang Hou,Xinghua Wang 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10
Variable nozzle turbine has advantages of improving engine low-speed performance; thus, it is widely applied in internal combustion engines. The present study analyzed the aerodynamic performance, especially the nozzle endwall leakage flow loss of a mixed flow turbine with variable nozzle, using 3D computational fluid dynamic simulation and test validation. Then, a partially-rotating vane nozzle was proposed to reduce the nozzle endwall clearance leakage flow to improve turbine efficiency. The results showed that at small nozzle opening condition, the front-part-vane rotating design can improve turbine efficiency up to 5.95 %, and the efficiency improvement of the rear-part-vane rotating design is approximately 5.08 %. At large nozzle opening condition, the front-part-vane rotating design has the same efficiency and flow capacity as the origin design, but the rear-part-vane rotating design cannot satisfy the flow capacity requirement. Detailed flow field analysis shows that the front-part-vane rotating design affects the velocity distribution at the rotor inlet due to nozzle endwall leakage flow. The leakage flow between the front part and the rear part of the nozzle causes a pressure jump at the pivoting axis.
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Dengfeng Yang,Li’ang Cao,Ce Yang,Dazhong Lao,Harold Sun 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.6
In this work, the influence of thickness and solidity of guide vane on the unsteady flow of a radial inflow turbine with variable nozzle has been numerically studied. Three vanes with the thickness changes from 0.3 to 0.1 and the solidity changes from 1.43 to 2.86, were chosen for this study. By investigating the unsteady flow field, it is found that the vane with low thickness and high solidity (vane B) can reduce shock by 75 % compared to the vane with high thickness and low solidity (base model); meanwhile, it can also mitigate the nozzle endwall leakage flow thus improves the flow uniformity of rotor inlet. As the intensity of shock and nozzle leakage flow were mitigated, the aerodynamic loading fluctuation of rotor blade can be weakened effectively, which will lead to improved rotor blades forced response. However, at small opening, vane B shows about 0.5 % lower efficiency than the base model; at large open condition, the efficiency degradation of vane B is up to 1.4 %. Therefore, there is a trade-off between the efficiency and forced response when choosing the nozzle vane solidity and thickness.
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