The Experts below are selected from a list of 1377 Experts worldwide ranked by ideXlab platform
Masato Furukawa - One of the best experts on this subject based on the ideXlab platform.
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large scale numerical simulation of unsteady flow field in a half Ducted Propeller fan using lattice boltzmann method
ASME JSME KSME 2015 Joint Fluids Engineering Conference AJKFluids 2015, 2015Co-Authors: Kazutoyo Yamada, Kazuya Kusano, Masato FurukawaAbstract:Recently, the lattice Boltzmann method (LBM) is being applied in turbomachinery field, regarded as a good candidate for tool of flow simulation as well as aerodynamic sound analysis.For better prediction of broadband noise with high frequecy, which is generally generated in high Reynolds number flows, not only high grid resolution is required to capture very small eddies of the sound source inside the turbulent boundary layer, but also the computation of acoustic field is often needed. In such case, the direct simulation of flow field and acoustic field is straight-forward and effective. However, the computational cost becomes extremely expensive. Moreover, for low Mach number flows the compressible Navier-Stokes simulation not only requires high-order scheme which is unsuitable for parallel computation, but also suffers from stiff problem. LBM is suitable for such simulation thanks to its advantages.In the present study, a large-scale numerical simulation of flow field around a half-Ducted Propeller fan is conDucted with LBM, and its result is validated by comparing with the experimental result.Copyright © 2015 by JSME
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detached eddy simulation of unsteady flow field and prediction of aerodynamic sound in a half Ducted Propeller fan
ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1 Symposia – Parts A B C and D, 2011Co-Authors: Kazuya Kusano, Kazutoyo Yamada, Jaeho Jeong, Masato FurukawaAbstract:Three-dimensional structures and unsteady nature of vortical flow fields in a half Ducted Propeller fan have been investigated by a detached eddy simulation (DES) based on k-ω two-equation turbulence model. The validity of the numerical simulation performed in the present study was demonstrated by the comparison to LDV measurement results. The simulation shows the tip vortex is so strong that it dominates the flow field near the rotor tip. The tip vortex does not impinge on the pressure surface of the adjacent blade directly, however it interacts with the shroud surface and induces a separation vortex on the shroud. Furthermore, this separation vortex interacts with the pressure surface of the adjacent blade. These flow structures cause high pressure fluctuation on the shroud surface and the blade pressure surface. Besides, sound pressure levels were predicted by Ffowcs William-Hawkings equation based on Lighthill’s acoustic analogy using the unsteady surface pressure data obtained by DES. As a result, the degree of contribution by each flow structure to overall sound has been estimated quantitatively.Copyright © 2011 by JSME
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three dimensional structure of separated and vortical flow in a half Ducted Propeller fan
2007 5th Joint ASME JSME Fluids Engineering Summer Conference FEDSM 2007, 2007Co-Authors: J H Jeong, Kazuya Takahashi, Kenichiro Iwakiri, Masato FurukawaAbstract:Three-dimensional structure of separated and vortical flow field has been investigated by numerical analysis on a half-Ducted Propeller fan. Complicated flow phenomena in the fan were captured by the Reynolds-averaged Navier-Stokes flow simulation (RANS) and a vortex structure identification technique based on the critical point theory. The flow field around the fan rotor is dominated by the tip leakage vortex. The tip leakage vortex starts to be formed near the blade mid-chord and grows nearly in the tangential direction without vortex breakdown. In the rotor passage, the high vorticity flow around the tip leakage vortex core is impinging on the pressure surface of the adjacent blade. It is expected that the behavior of the tip leakage vortex plays a major role in characteristics of the fan noise.Copyright © 2007 by ASME
Rajeev K Jaiman - One of the best experts on this subject based on the ideXlab platform.
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Investigation on the Performance of a Ducted Propeller in Oblique Flow
Journal of Offshore Mechanics and Arctic Engineering, 2019Co-Authors: Qin Zhang, Rajeev K Jaiman, Jing LiuAbstract:In this study, the Ducted Propeller has been numerically investigated under oblique flow, which is crucial and challenging for the design and safe operation of the thruster driven vessel and dynamic positioning (DP) system. A Reynolds-averaged Navier–Stokes (RANS) model has been first evaluated in the quasi-steady investigation on a single Ducted Propeller operating in open water condition, and then a hybrid RANS/LES model is adapted for the transient sliding mesh computations. A representative test geometry considered here is a marine model thruster, which is discretized with structured hexahedral cells, and the gap between the blade tip and nozzle is carefully meshed to capture the flow dynamics. The computational results are assessed by a systematic grid convergence study and compared with the available experimental data. As a part of the novel contribution, multiple incidence angles from 15 deg to 60 deg have been analyzed with different advance coefficients. The main emphasis has been placed on the hydrodynamic loads that act on the Propeller blades and nozzle as well as their variation with different configurations. The results reveal that while the nozzle absorbs much effort from the oblique flow, the imbalance between blades at different positions is still noticeable. Such unbalance flow dynamics on the blades, and the nozzle has a direct implication on the variation of thrust and torque of a marine thruster.
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numerical analysis on the wake dynamics of a Ducted Propeller
Ocean Engineering, 2019Co-Authors: Qin Zhang, Rajeev K JaimanAbstract:Abstract The wake dynamics and instabilities of a Ducted Propeller are numerically investigated at a Reynolds number of R e n = 1.765 × 10 5 . The numerical simulation is achieved by employing a hybrid RANS/LES model and the transient sliding mesh approach, and the computational results are compared with the available experimental data. The phase-averaged, time-averaged and instantaneous flow fields and the power spectra are considered as the analysis tools to shed light on the vortex-wake dynamics of the Ducted Propeller. The evolution of the vortical structures and the wake flow instability have been explored for zero inflow and various advance coefficients. A novel physical insight is provided on the instability mechanism associated with the breakdown of tip leakage vortex in the wake of the Ducted Propeller. It is found that the short-wave instability is the primary mechanism for the breakdown of the tip leakage vortex in the turbulent wake. Moreover, the zero inflow condition triggers the most complex wake flow patterns regarding the turbulence distribution among all the simulated cases. The spectral analysis indicates a much broader and more energy intensive frequencies for the zero inflow condition. The variation in the wake flow with the increase of advance coefficient is also discussed.
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Investigation on the performance of a Ducted Propeller in oblique flow
arXiv: Fluid Dynamics, 2018Co-Authors: Qin Zhang, Rajeev K Jaiman, Jing LiuAbstract:In this study, the Ducted Propeller has been numerically investigated under oblique flow, which is crucial and challenging for the design and safe operation of thruster driven vessel and dynamic positioning (DP) system. A Reynolds-Averaged Navier-Stokes (RANS) model has been first evaluated in the quasi-steady investigation on a single Ducted Propeller operating in open water condition, and then a hybrid RANS/LES model is adapted for the transient sliding mesh computations. A representative test geometry considered here is a marine model thruster which is discretized with structured hexahedral cells, and the gap between the blade tip and nozzle is carefully meshed to capture the flow dynamics. The computational results are assessed by a systematic grid convergence study and compared with the available experimental data. As a part of novel contribution, multiple incidence angles from $15^\circ$ to $60^\circ$ have been analyzed with varying advance coefficients. The main emphasis has been placed on the hydrodynamic loads that act on the Propeller blades and nozzle as well as their variation with different configurations. The results reveal that while the nozzle absorbs much effort from the oblique flow, the imbalance between blades at different positions is still noticeable. Such unbalance flow dynamics on the blades and the nozzle has a direct implication on the variation of thrust and torque of a marine thruster.
Qin Zhang - One of the best experts on this subject based on the ideXlab platform.
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Investigation on the Performance of a Ducted Propeller in Oblique Flow
Journal of Offshore Mechanics and Arctic Engineering, 2019Co-Authors: Qin Zhang, Rajeev K Jaiman, Jing LiuAbstract:In this study, the Ducted Propeller has been numerically investigated under oblique flow, which is crucial and challenging for the design and safe operation of the thruster driven vessel and dynamic positioning (DP) system. A Reynolds-averaged Navier–Stokes (RANS) model has been first evaluated in the quasi-steady investigation on a single Ducted Propeller operating in open water condition, and then a hybrid RANS/LES model is adapted for the transient sliding mesh computations. A representative test geometry considered here is a marine model thruster, which is discretized with structured hexahedral cells, and the gap between the blade tip and nozzle is carefully meshed to capture the flow dynamics. The computational results are assessed by a systematic grid convergence study and compared with the available experimental data. As a part of the novel contribution, multiple incidence angles from 15 deg to 60 deg have been analyzed with different advance coefficients. The main emphasis has been placed on the hydrodynamic loads that act on the Propeller blades and nozzle as well as their variation with different configurations. The results reveal that while the nozzle absorbs much effort from the oblique flow, the imbalance between blades at different positions is still noticeable. Such unbalance flow dynamics on the blades, and the nozzle has a direct implication on the variation of thrust and torque of a marine thruster.
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numerical analysis on the wake dynamics of a Ducted Propeller
Ocean Engineering, 2019Co-Authors: Qin Zhang, Rajeev K JaimanAbstract:Abstract The wake dynamics and instabilities of a Ducted Propeller are numerically investigated at a Reynolds number of R e n = 1.765 × 10 5 . The numerical simulation is achieved by employing a hybrid RANS/LES model and the transient sliding mesh approach, and the computational results are compared with the available experimental data. The phase-averaged, time-averaged and instantaneous flow fields and the power spectra are considered as the analysis tools to shed light on the vortex-wake dynamics of the Ducted Propeller. The evolution of the vortical structures and the wake flow instability have been explored for zero inflow and various advance coefficients. A novel physical insight is provided on the instability mechanism associated with the breakdown of tip leakage vortex in the wake of the Ducted Propeller. It is found that the short-wave instability is the primary mechanism for the breakdown of the tip leakage vortex in the turbulent wake. Moreover, the zero inflow condition triggers the most complex wake flow patterns regarding the turbulence distribution among all the simulated cases. The spectral analysis indicates a much broader and more energy intensive frequencies for the zero inflow condition. The variation in the wake flow with the increase of advance coefficient is also discussed.
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Investigation on the performance of a Ducted Propeller in oblique flow
arXiv: Fluid Dynamics, 2018Co-Authors: Qin Zhang, Rajeev K Jaiman, Jing LiuAbstract:In this study, the Ducted Propeller has been numerically investigated under oblique flow, which is crucial and challenging for the design and safe operation of thruster driven vessel and dynamic positioning (DP) system. A Reynolds-Averaged Navier-Stokes (RANS) model has been first evaluated in the quasi-steady investigation on a single Ducted Propeller operating in open water condition, and then a hybrid RANS/LES model is adapted for the transient sliding mesh computations. A representative test geometry considered here is a marine model thruster which is discretized with structured hexahedral cells, and the gap between the blade tip and nozzle is carefully meshed to capture the flow dynamics. The computational results are assessed by a systematic grid convergence study and compared with the available experimental data. As a part of novel contribution, multiple incidence angles from $15^\circ$ to $60^\circ$ have been analyzed with varying advance coefficients. The main emphasis has been placed on the hydrodynamic loads that act on the Propeller blades and nozzle as well as their variation with different configurations. The results reveal that while the nozzle absorbs much effort from the oblique flow, the imbalance between blades at different positions is still noticeable. Such unbalance flow dynamics on the blades and the nozzle has a direct implication on the variation of thrust and torque of a marine thruster.
Yang Chenjun - One of the best experts on this subject based on the ideXlab platform.
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the effect of stator parameters on performance of Ducted Propeller with pre swirl stators
Journal of Shanghai Jiaotong University, 2013Co-Authors: Rao Zhiqiang, Li Wei, Yang ChenjunAbstract:The turbulent characteristics of Ducted Propeller with pre-swirl stators were simulated numerically and the hydrodynamic performance was analyzed by RNG(Re-Normalisation Group) k-e viscous model.Compared with experimental and potential data,the numerical results are accurate and efficient.Furthermore open water performance of propulsion with different setting angle,section thickness and number of stator blades were predicted numerically.The effect of geometrical parameters on hydrodynamic performance was analyzed.
Liu Xiaolong - One of the best experts on this subject based on the ideXlab platform.
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a potential based panel method for prediction of steady and unsteady performances of Ducted Propeller with stators
Journal of Ship Mechanics, 2007Co-Authors: Liu XiaolongAbstract:A numerical procedure is developed to predict the steady and unsteady performances of Ducted Propeller with stators,in which a potential based panel method is applied for the flow around Propeller together with hub,duct and stators respectively.The interaction among them is treated in an iterative manner.To facilitate the computation,circumferentially averaged values of the induced velocities are adopted to consider the steady hydrodynamic interaction among Propeller,duct and stators.The unsteady hydrodynamic interaction among them is solved by an iterative method in the time domain.In addition,a simplified method for the unsteady interaction of vortex shedding among Propeller,duct and stators is proposed to reduce the computing time without the loss in the precision.Programs for the Propeller,stators and duct are run by turns until convergent results of hydrodynamic forces for each part are obtained.Numerical calculations are conDucted for some examples.Comparisons of the numerical results with the experimental data show good agreement.
