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  • 1
    In: Frontiers in Energy Research, Frontiers Media SA, Vol. 10 ( 2022-3-23)
    Abstract: This study concerns a multi-objective optimization of circumferential single grooved casing treatment for a low-reaction transonic rotor with ultra-high loading. The axial location, width and depth of the groove are investigated as design variables. The optimization problem seeks to fully extend the operation range of the rotor while minimizing efficiency degradation. Artificial neural network of radial basis function is applied to construct the surrogate model. The optimal groove configuration was determined using non-dominated sorting genetic algorithm II (NSGA II) in conjunction with technique for order preference by similarity to ideal solution (TOPSIS). Detailed analysis of flow field reveals that two flow features involving stability enhancement for the low-reaction rotor are the inhibition of shock/vortex interaction in the rotor tip region and the reduction or elimination of double-leakage tip gap flow. The blocking region located right downstream of the interface between the tip leakage flow and the main flow is decreased due to the tip unloading effect and recirculation flow induced by the groove. Additionally, the efficiency improvement can be observed as the intensity of tip leakage vortex decreases. Based on the single groove optimization, the prospect of a particular multiple groove casing configuration consisting of component grooves with varied geometrical dimensions is also discussed in the paper. The simulation results indicate that the new-type multiple groove configuration is more advantageous to the rotor’s performance.
    Type of Medium: Online Resource
    ISSN: 2296-598X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2733788-1
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  • 2
    Online Resource
    Online Resource
    Walter de Gruyter GmbH ; 2022
    In:  International Journal of Turbo & Jet-Engines Vol. 39, No. 3 ( 2022-08-26), p. 303-317
    In: International Journal of Turbo & Jet-Engines, Walter de Gruyter GmbH, Vol. 39, No. 3 ( 2022-08-26), p. 303-317
    Abstract: Unsteady pulsed suction (UPS) was applied as an unsteady flow control (UFC) technique in a certain highly loaded compressor cascade to control the flow separations. Only two bleed holes symmetrically mounted on the endwalls (one on the upper endwall and another on the lower endwall) were set up to achieve steady constant suction (SCS) and UPS. The improvements in aerodynamic performance by SCS and UPS under different time-averaged suction flow rates are firstly investigated and compared. The related unsteady aerodynamic parameters of UPS such as excitation frequency, excitation location, pitch angle, and skew angle are discussed and analyzed in detail. The results show that UPS can provide a better flow control effect than SCS with the same time-averaged dimensionless suction flow rate in the control of flow separation. The aerodynamic performance of compressor cascades can be significantly enhanced by UPS when unsteady aerodynamic parameters are in their optimum ranges. Based on the optimum parameters for UPS, the total pressure loss coefficient is reduced by 19 % only with the time-averaged dimensionless suction flow rate m s =0.4 %.
    Type of Medium: Online Resource
    ISSN: 0334-0082 , 2191-0332
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2022
    detail.hit.zdb_id: 2602427-5
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  • 3
    Online Resource
    Online Resource
    SAGE Publications ; 2018
    In:  Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering Vol. 232, No. 16 ( 2018-12), p. 3034-3048
    In: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, SAGE Publications, Vol. 232, No. 16 ( 2018-12), p. 3034-3048
    Abstract: In this paper, the synergistic effect between compound lean and aspiration on the aerodynamic performance of compressor cascades is discussed. Preliminary experimental data verify the accuracy of the computational fluid dynamics method adopted, and a thorough study on reciprocal effect among lean angle, aspirated flow fraction and aspiration streamwise location is conducted. The calculations show that, due to the shorter streamwise length of the re-grown boundary layer against adverse pressure gradient, the aspiration location located farther downstream from the leading edge can minimize the loss of the blade passage flow. With the application of blade lean, which is similar to the flow control mechanism in the unaspirated cascades, an increase in pressure at the suction surface corner is used to migrate the low momentum fluid from the corners towards the midspan of the suction surface. Meanwhile, the reduced aspirated flow velocity and the improved favorable pressure gradient in the lean anterior plenum can reduce the entropy rise through the plenum. Simultaneously, the suction power required in the blade passage flow is reduced with blade lean, while the suction power for the aspirated flow through the plenum shows the opposite trend.
    Type of Medium: Online Resource
    ISSN: 0954-4100 , 2041-3025
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2018
    detail.hit.zdb_id: 2032759-6
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  • 4
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2020
    In:  Journal of Thermal Science Vol. 29, No. 1 ( 2020-2), p. 219-231
    In: Journal of Thermal Science, Springer Science and Business Media LLC, Vol. 29, No. 1 ( 2020-2), p. 219-231
    Type of Medium: Online Resource
    ISSN: 1003-2169 , 1993-033X
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2280144-3
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  • 5
    In: Applied Thermal Engineering, Elsevier BV, Vol. 144 ( 2018-11), p. 291-304
    Type of Medium: Online Resource
    ISSN: 1359-4311
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2018
    detail.hit.zdb_id: 2019322-1
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  • 6
    Online Resource
    Online Resource
    SAGE Publications ; 2018
    In:  Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering Vol. 232, No. 1 ( 2018-01), p. 30-41
    In: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, SAGE Publications, Vol. 232, No. 1 ( 2018-01), p. 30-41
    Abstract: Boundary layer suction is considered to be an available approach to restraining or even eliminating flow separation and to improve the aerodynamic performance of the compressor. In this paper, a highly loaded axial-flow aspirated compressor based on a low-reaction design concept is investigated in detail to find an appropriate flow control strategy for boundary layer suction to achieve significant performance benefit. The flow control strategy consists mainly of the arrangement of suction hole and the aspirated flow rate. The geometrical models including aspiration cannulas, stator cavity and aspiration channel are novelly applied in this research to approach a real engineering application. Complete compressor maps are predicted by a three-dimensional computational fluid dynamics simulation. The distribution of the typical aerodynamic parameters and the partial flow structures are analysed at design and off-design conditions. Three-dimensional separation near the stall point is effectively suppressed by the aspiration on both hub and shroud, and better performance is achieved by a reasonable increase of aspirated flow rate; a peak efficiency of 0.91 and a total pressure ratio of 1.055 are attained at a total aspirated flow rate of 0.024 kg/s per passage. However, sudden turning of compressor maps at low inlet flow rate occurs without the aspiration on shroud, and a noticeable deterioration in performance occurs with the decreasing of the inlet flow rate. The main reason of performance deterioration is that the flow control efficiency of aspiration is not enough for effectively suppressing three-dimensional separation near the casing corner. The difference in the aspirated flow source is owed to the distinct flow feature at various locations caused by the aspiration efficiency of suction holes. A partial auto-readjustment feature of the suction flow rate with increasing flow separation has been found. The boundary layer suction with an appropriate flow control strategy is necessary for a higher efficiency, highly loaded aspiration compressor.
    Type of Medium: Online Resource
    ISSN: 0954-4100 , 2041-3025
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2018
    detail.hit.zdb_id: 2032759-6
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  • 7
    Online Resource
    Online Resource
    SAGE Publications ; 2019
    In:  Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering Vol. 233, No. 8 ( 2019-06), p. 2837-2852
    In: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, SAGE Publications, Vol. 233, No. 8 ( 2019-06), p. 2837-2852
    Abstract: Vortex structures of the separation flow fields in two-dimensional compressor cascades controlled by the boundary layer oscillating suction are numerically investigated. The proper orthogonal decomposition method is adopted to present the variation of characteristics owned by large-scale vortices. It is found that introducing unsteady excitations with proper frequencies into the steady aspiration results in a more effective control effect and the optimal oscillation frequency should be in line with the characteristic frequencies of the steady aspirated flow field. The separation flows can be decomposed in to several basic structures with the dominant one being in the manner of Karman vortex street regardless of the control method adopted. The boundary layer oscillating suction not only alleviates the separation by removing low-energy fluid, but also intensifies the harmonic flow element represented by proper orthogonal decomposition modes with others suppressed. The well-organized vortex shedding process could contribute to the loss reduction to some extent.
    Type of Medium: Online Resource
    ISSN: 0954-4100 , 2041-3025
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2019
    detail.hit.zdb_id: 2032759-6
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  • 8
    Online Resource
    Online Resource
    Elsevier BV ; 2022
    In:  Aerospace Science and Technology Vol. 130 ( 2022-11), p. 107925-
    In: Aerospace Science and Technology, Elsevier BV, Vol. 130 ( 2022-11), p. 107925-
    Type of Medium: Online Resource
    ISSN: 1270-9638
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2022
    detail.hit.zdb_id: 2014638-3
    SSG: 16,12
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  • 9
    Online Resource
    Online Resource
    Walter de Gruyter GmbH ; 2015
    In:  International Journal of Turbo & Jet-Engines Vol. 32, No. 2 ( 2015-01-28)
    In: International Journal of Turbo & Jet-Engines, Walter de Gruyter GmbH, Vol. 32, No. 2 ( 2015-01-28)
    Abstract: Experimental research has been carried out at low speed to investigate the effect of additional leading-edge surface roughness on a highly-loaded axial compressor cascade. A 5-hole aerodynamic probe has been traversed across one pitch to obtain the distribution of total pressure loss coefficient, secondary flow vector, flow angles and other aerodynamic parameters at the exit section. Meanwhile, ink-trace flow visualization has been used to measure the flow fields on the walls of cascades and a detailed topology structure of the flow on the walls has been obtained. Aerodynamic parameters and flow characteristics are compared by arranging different levels of roughness on various parts of the leading edge. The results show that adding surface roughness at the leading edge and on the suction side obviously influences cascade performance. Aggravated 3-D flow separation significantly increases the loss in cascades, and the loss increases till 60% when the level of emery paper is 80 mm. Even there is the potential to improve cascade performance in local area of cascade passage. The influence of the length of surface roughness on cascade performance is not always adverse, and which depends on the position of surface roughness.
    Type of Medium: Online Resource
    ISSN: 2191-0332 , 0334-0082
    Language: Unknown
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2015
    detail.hit.zdb_id: 2602427-5
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  • 10
    Online Resource
    Online Resource
    Walter de Gruyter GmbH ; 2021
    In:  International Journal of Turbo & Jet-Engines Vol. 38, No. 4 ( 2021-12-20), p. 421-431
    In: International Journal of Turbo & Jet-Engines, Walter de Gruyter GmbH, Vol. 38, No. 4 ( 2021-12-20), p. 421-431
    Abstract: The most important flow behaviour of supersonic compressor cascades is the shock wave boundary layer interaction (SWBLI). Large eddy simulation (LES) and multiple analysing methods are applied in current study to capture more details of the flow field. It is noted that the LES can catch the dual peaks feature near the SWBLI region with respect to the experimental results. Besides, SWBLI is not only the main losses source in the cascade, but also the most important origin of the unsteadiness behaviour. The high frequency signals correspond to the coherent structure in the boundary layer and dissipate downstream in the cascade, while the low frequency signals relate to the motion of the reflection point of the passage oblique shock wave and dominate the frequency spectrum downstream.
    Type of Medium: Online Resource
    ISSN: 0334-0082 , 2191-0332
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2021
    detail.hit.zdb_id: 2602427-5
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