The Experts below are selected from a list of 14796 Experts worldwide ranked by ideXlab platform
G Dyne - One of the best experts on this subject based on the ideXlab platform.
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STUDY OF PROPELLER-RUDDER INTERACTION BASED ON A LINEAR METHOD
International shipbuilding progress, 1995Co-Authors: G DyneAbstract:A linear method which calculates the steady forces of the propeller-rudder system working in a uniform flow is presented. A propeller with an infinite number of blades is used and modelled by a bound vortex sheet, a hub vortex filament and a series of free vortex sheets with an assumption that the free vortex sheets are undisturbed by the rudder. A lifting-line analysis method is incorporated to estimate the propeller performance characteristics. The rudder is represented by vortex and source/sink filaments on its mean plane. A vortex lattice method is used to estimate the rudder performance characteristics. Comparisons of the steady forces with experiments show a reasonable agreement. A rudder located in the accelerating flow just behind a propeller experiences a pressure drag. It is shown that this drag is an internal force which is counterbalanced by an increased propeller thrust. Due to the propeller induced tangential velocities in the slipstream a rudder thrust is created and the work done by the rudder thrust is a measure of the energy recovered by the rudder. The rudder in the test cases can recover up to 40% of the rotational energy and can increase the Open Water Efficiency by up to 1.7%.
Zhengdong Zhang - One of the best experts on this subject based on the ideXlab platform.
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Numerical Investigation of Different Tip Clearances Effect on the Hydrodynamic Performance of Pumpjet Propulsor
International Journal of Computational Methods, 2018Co-Authors: Denghui Qin, Qiaogao Huang, Guang Pan, Zhengdong ZhangAbstract:Previous studies show that the tip clearance loss limits the improvement of turbomachinery performance, and it is roughly in close relation with the gap size. In this study, a pumpjet propulsor (PJP) with different sizes of tip clearances ([Formula: see text], 0.5, 1, 2, 3[Formula: see text]mm) has been presented to investigate the influence of tip clearances on PJP. This analysis is based on computational fluid dynamic (CFD) method, and the SST k-[Formula: see text] turbulence model is applied. Calculations are carried out with a worldwide employed ducted propeller (the Ka4-70 propeller in 19A duct) to verify the numerical simulation. And the grid independence validation is discussed. The numerical simulation of PJP flow with different tip clearances is carried out. Results show that the Open Water Efficiency decreases gradually with the increase of tip clearance. The Efficiency decreasing is caused by the tip flow loss. The shape of tip vortex of PJP which consisted of tip-separation vortex and tip-leakage vortex is presented. Furthermore, the formation and spread process of tip vortex at different tip clearances are discussed. Then, the effect of different tip clearances on the pressure field of rotor blade is investigated. The main pressure area affected by different tip clearances is mainly concentrated in the area above 0.9 spanwise of the suction side of rotor blade. Beyond that, the effects of different tip clearances on the velocity field of PJP has been studied.
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numerical investigation of different tip clearances effect on the hydrodynamic performance of pumpjet propulsor
International Journal of Computational Methods, 2017Co-Authors: Qiaogao Huang, Zhengdong Zhang, Jiujiu KeAbstract:Previous studies show that the tip clearance loss limits the improvement of turbomachinery performance, and it is roughly in close relation with the gap size. In this study, a pumpjet propulsor (PJP) with different sizes of tip clearances (δ = 0.2, 0.5, 1, 2, 3mm) has been presented to investigate the influence of tip clearances on PJP. This analysis is based on computational fluid dynamic (CFD) method, and the SST k-ω turbulence model is applied. Calculations are carried out with a worldwide employed ducted propeller (the Ka4-70 propeller in 19A duct) to verify the numerical simulation. And the grid independence validation is discussed. The numerical simulation of PJP flow with different tip clearances is carried out. Results show that the Open Water Efficiency decreases gradually with the increase of tip clearance. The Efficiency decreasing is caused by the tip flow loss. The shape of tip vortex of PJP which consisted of tip-separation vortex and tip-leakage vortex is presented. Furthermore, the formati...
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Numerical Investigation of Different Tip Clearances Effect on the Hydrodynamic Performance of Pumpjet Propulsor
International Journal of Computational Methods, 2017Co-Authors: Denghui Qin, Qiaogao Huang, Guang Pan, Zhengdong ZhangAbstract:Previous studies show that the tip clearance loss limits the improvement of turbomachinery performance, and it is roughly in close relation with the gap size. In this study, a pumpjet propulsor (PJP) with different sizes of tip clearances (δ = 0.2, 0.5, 1, 2, 3mm) has been presented to investigate the influence of tip clearances on PJP. This analysis is based on computational fluid dynamic (CFD) method, and the SST k-ω turbulence model is applied. Calculations are carried out with a worldwide employed ducted propeller (the Ka4-70 propeller in 19A duct) to verify the numerical simulation. And the grid independence validation is discussed. The numerical simulation of PJP flow with different tip clearances is carried out. Results show that the Open Water Efficiency decreases gradually with the increase of tip clearance. The Efficiency decreasing is caused by the tip flow loss. The shape of tip vortex of PJP which consisted of tip-separation vortex and tip-leakage vortex is presented. Furthermore, the formation and spread process of tip vortex at different tip clearances are discussed. Then, the effect of different tip clearances on the pressure field of rotor blade is investigated. The main pressure area affected by different tip clearances is mainly concentrated in the area above 0.9 spanwise of the suction side of rotor blade. Beyond that, the effects of different tip clearances on the velocity field of PJP has been studied.
Chao Wang - One of the best experts on this subject based on the ideXlab platform.
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The Study on Optimization Design of Propeller Pitch
Journal of Coastal Research, 2015Co-Authors: Chao Wang, Xin Chang, Sheng HuangAbstract:ABSTRACT Wang, C.; Ye, L.; Chang, X., and Huang, S., 2015. The study on optimization design of propeller pitch. With the increasing requirements of the hydrodynamic performance of the propeller, the optimization design of propeller has been gradually taken by people. With the DTRC series propellers as master model, this paper uses the theoretical prediction program based on surface panel method and combines with particle swarm optimization algorithm to study the optimization of propeller pitch (the other parameter is the same as the original propeller). In the optimization process, there are two different kinds of pitch expression (linear superposition method and Bezier function method) to fit radial distribution of pitch. With Open Water Efficiency as the goal, the propeller is optimized and then discusses the influence of skew on Open Water Efficiency. The result shows that Bezier method fits pitch curve more smoothly compared with hick-henne method, and that under the condition of meeting the thrust co...
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Research on the Optimization Design of Propeller Considered the Off-designed Conditions
Proceedings of the 2015 International Industrial Informatics and Computer Engineering Conference, 2015Co-Authors: Shuai Sun, Xin Chang, Chao WangAbstract:In order to improve the performance of propeller,the propeller Efficiency optimization method under the off-designed conditions were studied. Taking the Open Water Efficiency around the designed velocity of parent propeller as the objective function, taking the radial distribution of pitch ratio as the optimization variables and taking the thrust and the cavitation performance of the propeller as the constraints and the optimization mathematical model was established. The panel method was used to solve the hydrodynamic performance of propeller and the cavitation performance was described by the BaiLiEr merchant margin line. Based on the simple genetic algorithm, the optimized radial distribution of the pitch ratio was solved. The optimized results show that due to the changes of ship speed the method which takes the Efficiency of design velocity as the objective function fails to achieve the expected energy-saving. And the multiple operating points corresponding Efficiency around designed speed was supposed to considered.
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ICSI (1) - The Application of Particle Swarm Optimization Arithmetic in Propeller Design
Lecture Notes in Computer Science, 2013Co-Authors: Chao Wang, Guoliang Wang, Wanlong Ren, Chunyu Guo, Bin ZhouAbstract:In order to obtain a propeller with good Efficiency and cavitation performance, the propeller sections were optimization designed using particle swarm optimization (PSO) method. An interactive calculation method was used in design process for the circulation distribution of designed propeller was not coincident with optimization circulation. The difference of circulation was defined as correction factor to adjust lift coefficients of sections. PSO method was used to optimize sections to improve the lift-to-drag ratio and pressure distribution. The convergence condition was the circulation distribution fulfilled optimum circulation distribution form. A MAU propeller was optimized using the method. Hydrodynamic performances of propeller and sections’ pressure distribution of original propeller were compared with optimized propeller. It indicates from the results that compared with traditional method, the PSO method is simpler in theory and cost less computing time. The Open Water Efficiency of optimized propeller advanced obviously. The min negative pressure is smaller which means the cavitation performance is better.
Qiaogao Huang - One of the best experts on this subject based on the ideXlab platform.
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Numerical Investigation of Different Tip Clearances Effect on the Hydrodynamic Performance of Pumpjet Propulsor
International Journal of Computational Methods, 2018Co-Authors: Denghui Qin, Qiaogao Huang, Guang Pan, Zhengdong ZhangAbstract:Previous studies show that the tip clearance loss limits the improvement of turbomachinery performance, and it is roughly in close relation with the gap size. In this study, a pumpjet propulsor (PJP) with different sizes of tip clearances ([Formula: see text], 0.5, 1, 2, 3[Formula: see text]mm) has been presented to investigate the influence of tip clearances on PJP. This analysis is based on computational fluid dynamic (CFD) method, and the SST k-[Formula: see text] turbulence model is applied. Calculations are carried out with a worldwide employed ducted propeller (the Ka4-70 propeller in 19A duct) to verify the numerical simulation. And the grid independence validation is discussed. The numerical simulation of PJP flow with different tip clearances is carried out. Results show that the Open Water Efficiency decreases gradually with the increase of tip clearance. The Efficiency decreasing is caused by the tip flow loss. The shape of tip vortex of PJP which consisted of tip-separation vortex and tip-leakage vortex is presented. Furthermore, the formation and spread process of tip vortex at different tip clearances are discussed. Then, the effect of different tip clearances on the pressure field of rotor blade is investigated. The main pressure area affected by different tip clearances is mainly concentrated in the area above 0.9 spanwise of the suction side of rotor blade. Beyond that, the effects of different tip clearances on the velocity field of PJP has been studied.
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numerical investigation of different tip clearances effect on the hydrodynamic performance of pumpjet propulsor
International Journal of Computational Methods, 2017Co-Authors: Qiaogao Huang, Zhengdong Zhang, Jiujiu KeAbstract:Previous studies show that the tip clearance loss limits the improvement of turbomachinery performance, and it is roughly in close relation with the gap size. In this study, a pumpjet propulsor (PJP) with different sizes of tip clearances (δ = 0.2, 0.5, 1, 2, 3mm) has been presented to investigate the influence of tip clearances on PJP. This analysis is based on computational fluid dynamic (CFD) method, and the SST k-ω turbulence model is applied. Calculations are carried out with a worldwide employed ducted propeller (the Ka4-70 propeller in 19A duct) to verify the numerical simulation. And the grid independence validation is discussed. The numerical simulation of PJP flow with different tip clearances is carried out. Results show that the Open Water Efficiency decreases gradually with the increase of tip clearance. The Efficiency decreasing is caused by the tip flow loss. The shape of tip vortex of PJP which consisted of tip-separation vortex and tip-leakage vortex is presented. Furthermore, the formati...
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Numerical Investigation of Different Tip Clearances Effect on the Hydrodynamic Performance of Pumpjet Propulsor
International Journal of Computational Methods, 2017Co-Authors: Denghui Qin, Qiaogao Huang, Guang Pan, Zhengdong ZhangAbstract:Previous studies show that the tip clearance loss limits the improvement of turbomachinery performance, and it is roughly in close relation with the gap size. In this study, a pumpjet propulsor (PJP) with different sizes of tip clearances (δ = 0.2, 0.5, 1, 2, 3mm) has been presented to investigate the influence of tip clearances on PJP. This analysis is based on computational fluid dynamic (CFD) method, and the SST k-ω turbulence model is applied. Calculations are carried out with a worldwide employed ducted propeller (the Ka4-70 propeller in 19A duct) to verify the numerical simulation. And the grid independence validation is discussed. The numerical simulation of PJP flow with different tip clearances is carried out. Results show that the Open Water Efficiency decreases gradually with the increase of tip clearance. The Efficiency decreasing is caused by the tip flow loss. The shape of tip vortex of PJP which consisted of tip-separation vortex and tip-leakage vortex is presented. Furthermore, the formation and spread process of tip vortex at different tip clearances are discussed. Then, the effect of different tip clearances on the pressure field of rotor blade is investigated. The main pressure area affected by different tip clearances is mainly concentrated in the area above 0.9 spanwise of the suction side of rotor blade. Beyond that, the effects of different tip clearances on the velocity field of PJP has been studied.
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Numerical Simulation of Cavitation Characteristics for Pump-jet Propeller
Journal of Physics: Conference Series, 2015Co-Authors: Yao Shi, Qiaogao Huang, Guang Pan, Du XiaoxuAbstract:With k — e turbulent model, non-cavitating performance of a pump-jet propeller was obtained by calculating RANS equations. The comparison between calculation results and experiment data shown that the numerical model and method was reliable. The cavitating hydrodynamic performance of it was calculated and analyzed with mixture homogeneous flow cavitation model based on Rayleigh-Plesset equations and sliding mesh. The effects of different inlet velocity ratio, cavitation number and flow velocity on cavitation characteristics of pump-jet were studied. When the cavitation occurred on the blades, the propeller thrust and torque decreased significantly, thereby causing Open Water Efficiency reduced 15%. For the same cavitation number, as the inlet velocity ratio decreased, the pump-jet propeller blade cavitation phenomenon was more obvious. While for the same ratio, the smaller the number of cavitation, cavitation phenomenon was more remarkable. The more significant was that while the cavitation number was greater than a certain value, the blade cavitation phenomenon disappeared.
Dejan Radojčić - One of the best experts on this subject based on the ideXlab platform.
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Additional Topics on Resistance, Propulsion and Powering
Power Prediction Modeling of Conventional High-Speed Craft, 2019Co-Authors: Dejan Radojčić, Milan Kalajdžić, Aleksandar SimicAbstract:Mathematical models for prediction of bare hull resistance and propeller’s Open Water Efficiency have been outlined in Chaps. 8 and 9, respectively.
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Propeller’s Open-Water Efficiency Modeling
Power Prediction Modeling of Conventional High-Speed Craft, 2019Co-Authors: Dejan Radojčić, Milan Kalajdžić, Aleksandar SimicAbstract:Modeling propeller’s Open Water hydrodynamic characteristics is in many respects different from modeling resistance, although the same tools and methods are used. Two main differences should be emphasized:
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Propeller’s Open-Water Efficiency Prediction
Reflections on Power Prediction Modeling of Conventional High-Speed Craft, 2018Co-Authors: Dejan RadojčićAbstract:Modeling propeller’s Open Water hydrodynamic characteristics is in many respects different from modeling resistance, although the same tools and methods are used. Two main differences should be emphasized: 1. Dependent variables that should be modeled simultaneously are thrust coefficient and torque coefficient. By definition, these coefficients are interrelated (linked) through the expression for the Open Water Efficiency. 2. While the dependent variables are always KT and KQ, the independent ones are some or all of the following: advance coefficient, pitch ratio, area ratio, number of blades and cavitation number. This pre-determination makes modeling easier, since there is no need to search for optimum independent variables best suited for a particular propeller series.
