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RISS 인기검색어
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- 저자 : Dazheng Wang (검색결과 3 건)
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Korkut, Emin,Atlar, Mehmet,Wang, Dazheng The Society of Naval Architects of Korea 2013 International Journal of Naval Architecture and Oc Vol.5 No.1
During the final quarter of the last century considerable efforts have been spent to reduce the hull pressure fluctuations caused by unsteady propeller cavitation. This has resulted in further changes in propeller design characteristics including increased skew, tip unloading and introduction of "New Blade Sections" (NBS) designed on the basis of the so-called Eppler code. An experimental study was carried out to investigate flow characteristics of alternative two-dimensional (2-D) blade sections of rectangular planform, one of which was the New Blade Section (NBS) developed in Newcastle University and other was based on the well-known National Advisory Committee for Aeronautics (NACA) section. The experiments comprised the cavitation observations and the measurements of the local velocity distribution around the blade sections by using a 2-D Laser Doppler Anemometry (LDA) system. Analysis of the cavitation tests demonstrated that the two blade sections presented very similar bucket shapes with virtually no width at the bottom but relatively favourable buckets arms at the suction and pressure sides for the NACA section. Similarly, pressure analysis of the sections displayed a slightly larger value for the NBS pressure peak. The comparative overall pressure distributions around the sections suggested that the NBS might be more susceptible to cavitation than the NACA section. This can be closely related to the fundamental shape of the NBS with very fine leading edge. Therefore a further investigation into the modification of the leading edge should be considered to improve the cavitation behaviour of the NBS.
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Emin Korkut,Mehmet Atlar,Dazheng Wang 대한조선학회 2013 International Journal of Naval Architecture and Oc Vol.5 No.1
During the final quarter of the last century considerable efforts have been spent to reduce the hull pressure fluctuations caused by unsteady propeller cavitation. This has resulted in further changes in propeller design characteristics including increased skew, tip unloading and introduction of “New Blade Sections” (NBS) designed on the basis of the so-called Eppler code. An experimental study was carried out to investigate flow characteristics of alternative two-dimensional (2-D) blade sections of rectangular planform, one of which was the New Blade Section (NBS) developed in Newcastle University and other was based on the well-known National Advisory Committee for Aeronautics (NACA) section. The experiments comprised the cavitation observations and the measurements of the local velocity distribution around the blade sections by using a 2-D Laser Doppler Anemometry (LDA) system. Analysis of the cavitation tests demonstrated that the two blade sections presented very similar bucket shapes with virtually no width at the bottom but relatively favourable buckets arms at the suction and pressure sides for the NACA section. Similarly, pressure analysis of the sections displayed a slightly larger value for the NBS pressure peak. The comparative overall pressure distributions around the sections suggested that the NBS might be more susceptible to cavitation than the NACA section. This can be closely related to the fundamental shape of the NBS with very fine leading edge. Therefore a further investigation into the modification of the leading edge should be considered to improve the cavitation behaviour of the NBS.
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( Da Zheng ),( Qinyuan Wang ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2
Taking the toppling deformation body before the dam of a hydropower station as the research object, the physical model of the slope is established on the basis of geological cognition and similarity theory, the undercutting of river valleys is simulated by the method of graded excavation, the key hazard factor of deep toppling deformation and the disaster pattern of the counter-tilt layered rock slope under gravity are studied by the 4-stage centrifuge model test. The results show that: (1) The occurrence, development and destruction of deep toppling deformation of counter-tilt layered rock slopes have to go through a long geological history time, the accumulation of energy and deformation is a long process, and the increase of deformation is closely related to the change of external conditions (such as excavation, earthquake, etc.). (2) Lithological conditions (relatively weak rock mass), structural conditions (appropriate layer thickness and dip angle), and external conditions (undercutting of river valleys or excavation of slopes) are key factors for deep toppling deformation, while air conditions are the key hazard factor for deep toppling deformation damage. (3) The deep toppling deformation can form multiple bending belts with different depth after the multi-valley cutting (multi-level excavation), the bending belt is gradually connected from the slope foot to the top, and eventually becomes the failure boundary, the development and penetration of the bending belt may result in the overall shear failure of the slope along the bending belt.
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