The Computational Fluid Dynamics （CFD） approach is adopted to study the steady and unsteady performances of the podded propulsor by the Fluent software package. While the interactions of the propeller blades with th...The Computational Fluid Dynamics （CFD） approach is adopted to study the steady and unsteady performances of the podded propulsor by the Fluent software package. While the interactions of the propeller blades with the pod and strut are time-dependent by nature, the mixing plane model is employed firstly to predict the steady performance, where the interactions are time-averaged. Numerical experiments are carried out with systematically varied mesh sizes to investigate the dependence of the predicted force values on the mesh sizes. Furthermore, the sliding mesh model is employed to simulate the unsteady interactions between the blades, pod and strut. Based on the numerical results, the characteristics of unsteady hydrodynamic forces are discussed, and the applicability of the mixing plane model is investigated for puller-type podded propulsor.展开更多
This paper introduces a newly developed Unmanned Wave Glide Vehicle （UWGV）, which is driven only by extracting energy from gravity waves, and presents a comprehensive study on the propulsion performance of the UWGV...This paper introduces a newly developed Unmanned Wave Glide Vehicle （UWGV）, which is driven only by extracting energy from gravity waves, and presents a comprehensive study on the propulsion performance of the UWGV＇s propulsor-Wave Glide Propulsor （WGP） in a regular wave. By simplifying the WGP as six 2D tandem asynchronous flapping foils （TAFFs）, a CFD method based on Navier-Stokes equations was first used to analyze the hydrodynamic performance of TAFFs with different parameters of non-dimensional wave length rn and non-dimensional wave height n. Then, a series of hydrodynamic experiments were performed. The computational results agree well with the experimental results when n〈0.07 and both of them show the thrust force and input power of the WGP are larger at smaller m or larger n. By analyzing the flow field of TAFFs, we can see that a larger m is beneficial to the forming, merging and shredding of the TAFFs＇ vortices; as TAFFs are arranged in tandem and have the same motions, the leading edge vortex and wake vortex of the TAFFs are meaningful for improving the thrust force of their adjacent ones.展开更多
The flapping motion of a flexible propulsor near the ground was simulated using the immersed boundary method. The hydrodynamic benefits of the propulsor near the ground were explored by varying the heaving frequency (...The flapping motion of a flexible propulsor near the ground was simulated using the immersed boundary method. The hydrodynamic benefits of the propulsor near the ground were explored by varying the heaving frequency (St) of the leading edge of the flexible propulsor. Propulsion near the ground had some advantages in generating thrust and propelling faster than propulsion away from the ground. The mode analysis and flapping amplitude along the Lagrangian coordinate were examined to analyze the kinematics as a function of the ground proximity (d) and St. The trailing edge amplitude (\(a_\mathrm{tail}\)) and the net thrust (\(\overline{{F}}_x\)) were influenced by St of the flexible propulsor. The vortical structures in the wake were analyzed for different flapping conditions.展开更多
The unsteady performance of drag and double reverse propeller podded propulsors in open water was numerically simulated using a computational fluid dynamics （CFD） method. A moving mesh method was used to more realis...The unsteady performance of drag and double reverse propeller podded propulsors in open water was numerically simulated using a computational fluid dynamics （CFD） method. A moving mesh method was used to more realistically simulate propulsor working conditions, and the thrust, torque, and lateral force coefficients of both propulsors were compared and analyzed. Forces acting on different parts of the propulsors along with the flow field distribution of steady and unsteady results at different advance coefficients were compared. Moreover, the change of the lateral force and the difference between the abovementioned two methods were mainly analyzed. It was shown that the thrust and torque results of both methods were similar, with the lateral force results having the highest deviation展开更多
Experimental tests were conducted to evaluate the hydrodynamic performance of an L-type podded propulsor in straight-ahead motion and off-design conditions using an open-water measuring instrument developed by the aut...Experimental tests were conducted to evaluate the hydrodynamic performance of an L-type podded propulsor in straight-ahead motion and off-design conditions using an open-water measuring instrument developed by the authors for podded propulsors, a ship model towing tank, and under water particle image velocimetry （PIV） measurement systems. Under the three types of conditions, the main parameters of an L-type podded propulsor were measured, including the propeller thrust and torque, as well as the thrust, side force, and moment of the whole pod unit.In addition, the flow field on the section between the propeller and the strut was analyzed. Experimental results demonstrate that the dynamic azimuthing rate and direction and the turning direction affect the forces on the propeller and the whole pod unit. Forces are asymmetrically distributed between the left and right azimuthing directions because of the effect of propeller rotation. The findings of this study provide a foundation for further research on L-type podded propulsors.展开更多
Based on the model test of podded propulsor in straight forward motion, the paper presents the results of the effects of geometric parameters on the propulsive characteristics of podded propulsors in viscous flow. Thr...Based on the model test of podded propulsor in straight forward motion, the paper presents the results of the effects of geometric parameters on the propulsive characteristics of podded propulsors in viscous flow. Three main geometrical parameters, i.e. pod diameter, strut distance from the propeller plane, and the maximum thickness of strut are studied with systematically varied geometry while the parameters of propeller blades are fixed. The RANS approach is adopted to study the steady perfomaance using the Huent software package. While the interactions of the propeller blades with the pod and strut are time-dependent by nature, the mixing plane model is employed to predict the steady perfomlance. In considera- tion of the complexity, the research does not deal with the effects of the combination of such three main parameters.展开更多
Previous studies show that the tip clearance loss limits the improvement of pumpjet propulsor (PJP) performance,and the tip clearance flow field is the most complicated part of PJP flow.In this work,the non-cavitation...Previous studies show that the tip clearance loss limits the improvement of pumpjet propulsor (PJP) performance,and the tip clearance flow field is the most complicated part of PJP flow.In this work,the non-cavitation and cavitation hydrodynamic performances of PJP with a tip clearance size of 1 mm are obtained by using the detached-eddy simulation (DES).At constant oncoming velocity,cavitation first occurs on the duct and then disappears with the decrease of the advance ratio.The rotor blade cavitation occurs at the low advance ratio and comprises tip clearance cavitation,tip leakage cavitation,and blade sheet cavitation.In the rotor region,the typical vortices include tip separation vortex,tip leakage vortex,trailing edge shedding vortex,and blade root horseshoe vortex.Combined with the pressure distribution,both the Q and λ2 criteria give reliable results of vortex identification.The cavitation causes an expansion of tip leakage vortex in the circumferential direction and decreases the intensities of tip separation vortex in the whole tip clearance area and tip leakage vortex in the cavitation area,and enhances the strength of tip leakage vortex in the downstream non-cavitation area.展开更多
During ice-breaking navigation, a massive amount of crushed ice blocks with different sizes is accumulated under the hull of an ice-going ship. This ice slides into the flow field in the forward side of the podded pro...During ice-breaking navigation, a massive amount of crushed ice blocks with different sizes is accumulated under the hull of an ice-going ship. This ice slides into the flow field in the forward side of the podded propulsor, affecting the surrounding flow field and aggravating the non-uniformity of the propeller wake. A pulsating load is formed on the propeller, which affects the hydrodynamic performance of the podded propulsor. To study the changes in the propeller hydrodynamic performance during the ice podded propulsor interaction, the overlapping grid technique is used to simulate the unsteady hydrodynamic performance of the podded propulsor at different propeller rotation angles and different ice block sizes. Hence, the hydrodynamic blade behavior during propeller rotation under the interaction between the ice and podded propulsor is discussed. The unsteady propeller loads and surrounding flow fields obtained for ice blocks with different sizes interacting with the podded propulsor are analyzed in detail. The variation in the hydrodynamic performance during the circular motion of a propeller and the influence of ice size variation on the propeller thrust and torque are determined. The calculation results have certain reference significance for experiment-based research, theoretical calculations and numerical simulation concerning ice podded propulsor interaction.展开更多
A mathematical model of podded propulsors was established in order to investigate the influence of fins. The hydrodynamic performance of podded propulsors with and without fins was calculated, with interactions betwee...A mathematical model of podded propulsors was established in order to investigate the influence of fins. The hydrodynamic performance of podded propulsors with and without fins was calculated, with interactions between propellers and pods and fins derived by iterative calculation. The differential equation based on velocity potential was adopted and hyperboloidal panels were used to avoid gaps between surface panels. The Newton-Raphson iterative procedure was used on the trailing edge to meet the pressure Kutta condition. The velocity distribution was calculated with the Yanagizawa method to eliminate the singularity caused by use of the numerical differential. Comparisons of the performance of podded propulsors with different fins showed that the thrust of propeller in a podded propulsor with fins is greater. The resistance of the pod is also reduced because of the thrust of the fin. The hydrodynamic performance of a podded propulsor with two fins is found to be best, the performance of a podded propulsor with one fin is not as good as two fins, and the performance of the common type is the worst.展开更多
Normally,small unmanned vessels used to clean floating litter on water adopt a paddle wheel as a propulsor to satisfy its shallow-draft requirements;however,this type of propulsor has bulky structures and inefficient ...Normally,small unmanned vessels used to clean floating litter on water adopt a paddle wheel as a propulsor to satisfy its shallow-draft requirements;however,this type of propulsor has bulky structures and inefficient propulsion.In this study,a novel tandem paddles propulsor(TPP)was developed,and its propulsion performance was analyzed and compared with that of a paddle wheel propulsor(PWP).Using the RNG k-εturbulence model and sliding grid technique,the hydrodynamic performance of the PWP was simulated in computational fluid dynamics(CFD)software to verify the reliability of the numerical method.Subsequently,the propulsion performances of the two types of propulsors were simulated with different immersion depths and advanced coefficients,and the differences in their mechanical characteristics and flow field evolution were discussed and compared.The results indicate that the proposed TPP generates 2.75 times more thrust and 1.99 times greater efficiency than the PWP,exhibiting superior propulsion capability in shallow-draft vessels.展开更多
为合理地预测非定常力作用下泵喷推进系统的结构响应,流固耦合效应所产生的水动力阻尼不可忽略。不同模态的水动力阻尼量级决定了该模态对系统响应的贡献。针对泵喷推进系统的多模态水动力阻尼问题,首先基于计算流体动力学(computationa...为合理地预测非定常力作用下泵喷推进系统的结构响应,流固耦合效应所产生的水动力阻尼不可忽略。不同模态的水动力阻尼量级决定了该模态对系统响应的贡献。针对泵喷推进系统的多模态水动力阻尼问题,首先基于计算流体动力学(computational fluid dynamics,CFD)和耦合有限法(finite element method,FEM),采用能量法对螺旋桨水动力阻尼特性展开数值研究。结果表明,能量法适用于水下叶轮机械水动力阻尼的研究,满足工程分析的需要。随后,基于能量法对简化泵喷推进系统多模态水动力阻尼特性展开数值研究,从非定常力做功的角度揭示影响水动力阻尼大小的主导因素。结果表明:转子主导的模态水动力阻尼较轴系主导模态的水动力阻尼高,转子轴系耦合模态水动力阻尼幅值大小则不固定,其主要取决于耦合系统中转子的振型及固有频率的大小;导管振动主导的模态水动力阻尼远高于定子振动带动导管运动的模态。水动力阻尼具有明显的模态依赖性,不同模态阻尼比幅值差距大,非定常力做功的影响显著高于固有频率。展开更多
A podded propulsor in viscous flow is numerically simulated in this article. The region of fluid is divided into efficient calculation grids. The pressure and viscous force of blades, pod and strut are obtained as fun...A podded propulsor in viscous flow is numerically simulated in this article. The region of fluid is divided into efficient calculation grids. The pressure and viscous force of blades, pod and strut are obtained as functions of an advance coefficient. The steady result is used as a base in the unsteady simulation to obtain a solution more quickly. The distributions of the thrust and torque fluctuations of the key blade in one revolution are obtained. The c^lculation results from the mixing plane on steady conditions are compared with those obtained from the sliding mesh model on unsteady conditions. The User-Defined Function （UDF） method is used to simulate the influence of ship hull on the non-uniform wake of the propeller.展开更多
基金supported by the"Knowledge-based Ship Design Hyper-Integrated Platform(KSHIP)"a key project of the Ministry of Education and the Ministry of Finance of China
文摘The Computational Fluid Dynamics （CFD） approach is adopted to study the steady and unsteady performances of the podded propulsor by the Fluent software package. While the interactions of the propeller blades with the pod and strut are time-dependent by nature, the mixing plane model is employed firstly to predict the steady performance, where the interactions are time-averaged. Numerical experiments are carried out with systematically varied mesh sizes to investigate the dependence of the predicted force values on the mesh sizes. Furthermore, the sliding mesh model is employed to simulate the unsteady interactions between the blades, pod and strut. Based on the numerical results, the characteristics of unsteady hydrodynamic forces are discussed, and the applicability of the mixing plane model is investigated for puller-type podded propulsor.
基金financially supported by the National Natural Science Foundation of China(Grant No.51479039)China Postdoctoral Science Foundation(Grant No.2013M540271)
文摘This paper introduces a newly developed Unmanned Wave Glide Vehicle （UWGV）, which is driven only by extracting energy from gravity waves, and presents a comprehensive study on the propulsion performance of the UWGV＇s propulsor-Wave Glide Propulsor （WGP） in a regular wave. By simplifying the WGP as six 2D tandem asynchronous flapping foils （TAFFs）, a CFD method based on Navier-Stokes equations was first used to analyze the hydrodynamic performance of TAFFs with different parameters of non-dimensional wave length rn and non-dimensional wave height n. Then, a series of hydrodynamic experiments were performed. The computational results agree well with the experimental results when n〈0.07 and both of them show the thrust force and input power of the WGP are larger at smaller m or larger n. By analyzing the flow field of TAFFs, we can see that a larger m is beneficial to the forming, merging and shredding of the TAFFs＇ vortices; as TAFFs are arranged in tandem and have the same motions, the leading edge vortex and wake vortex of the TAFFs are meaningful for improving the thrust force of their adjacent ones.
基金supported by the Creative Research Initiatives (Grant 2016-004749) program of the National Research Foundation of Korea (MSIP)
文摘The flapping motion of a flexible propulsor near the ground was simulated using the immersed boundary method. The hydrodynamic benefits of the propulsor near the ground were explored by varying the heaving frequency (St) of the leading edge of the flexible propulsor. Propulsion near the ground had some advantages in generating thrust and propelling faster than propulsion away from the ground. The mode analysis and flapping amplitude along the Lagrangian coordinate were examined to analyze the kinematics as a function of the ground proximity (d) and St. The trailing edge amplitude (\(a_\mathrm{tail}\)) and the net thrust (\(\overline{{F}}_x\)) were influenced by St of the flexible propulsor. The vortical structures in the wake were analyzed for different flapping conditions.
基金Supported by National Natural Science Foundation of China （41176074, 51209048,51379043,51409063） High tech ship research project of Ministry of industry and technology （G014613002） The support plan for youth backbone teachers of Harbin Engineering University （HEUCFQ1408）
文摘The unsteady performance of drag and double reverse propeller podded propulsors in open water was numerically simulated using a computational fluid dynamics （CFD） method. A moving mesh method was used to more realistically simulate propulsor working conditions, and the thrust, torque, and lateral force coefficients of both propulsors were compared and analyzed. Forces acting on different parts of the propulsors along with the flow field distribution of steady and unsteady results at different advance coefficients were compared. Moreover, the change of the lateral force and the difference between the abovementioned two methods were mainly analyzed. It was shown that the thrust and torque results of both methods were similar, with the lateral force results having the highest deviation
基金Foundation item： Supported by the National Natural Science Foundation of China （Grant Nos. 41176074, 51379043 and 51409063）Acknowledgement This project was supported by the National Natural Science Foundation of China （Grant Nos. 41176074,51379043 and 51409063） and was conducted in response to the great support received from a basic research project entitled ＂Multihull Ship Technology Key Laboratory of Fundamental Science for National Defence＂, which was conducted at Harbin Engineering University. The authors would like to extend their sincere gratitude to their colleagues in the towing tank laboratory.
文摘Experimental tests were conducted to evaluate the hydrodynamic performance of an L-type podded propulsor in straight-ahead motion and off-design conditions using an open-water measuring instrument developed by the authors for podded propulsors, a ship model towing tank, and under water particle image velocimetry （PIV） measurement systems. Under the three types of conditions, the main parameters of an L-type podded propulsor were measured, including the propeller thrust and torque, as well as the thrust, side force, and moment of the whole pod unit.In addition, the flow field on the section between the propeller and the strut was analyzed. Experimental results demonstrate that the dynamic azimuthing rate and direction and the turning direction affect the forces on the propeller and the whole pod unit. Forces are asymmetrically distributed between the left and right azimuthing directions because of the effect of propeller rotation. The findings of this study provide a foundation for further research on L-type podded propulsors.
基金supported by the Fundamental Research Funds for the Central Universities (Grant No.HEUCFT1001)the"Knowledge-based Ship Design Hyper-Integrated Plat form(KSHIP)",a Key Project of the Ministry of Education and the Ministry of Finance of China
文摘Based on the model test of podded propulsor in straight forward motion, the paper presents the results of the effects of geometric parameters on the propulsive characteristics of podded propulsors in viscous flow. Three main geometrical parameters, i.e. pod diameter, strut distance from the propeller plane, and the maximum thickness of strut are studied with systematically varied geometry while the parameters of propeller blades are fixed. The RANS approach is adopted to study the steady perfomaance using the Huent software package. While the interactions of the propeller blades with the pod and strut are time-dependent by nature, the mixing plane model is employed to predict the steady perfomlance. In considera- tion of the complexity, the research does not deal with the effects of the combination of such three main parameters.
基金the National Natural Science Foundation of China(Nos.51709229 and 51879220)the Natural Science Basic Research Plan in Shaanxi Province(No.2018JQ5092)the Fundamental Research Funds for the Central Universities of China(No.3102019HHZY030019)。
文摘Previous studies show that the tip clearance loss limits the improvement of pumpjet propulsor (PJP) performance,and the tip clearance flow field is the most complicated part of PJP flow.In this work,the non-cavitation and cavitation hydrodynamic performances of PJP with a tip clearance size of 1 mm are obtained by using the detached-eddy simulation (DES).At constant oncoming velocity,cavitation first occurs on the duct and then disappears with the decrease of the advance ratio.The rotor blade cavitation occurs at the low advance ratio and comprises tip clearance cavitation,tip leakage cavitation,and blade sheet cavitation.In the rotor region,the typical vortices include tip separation vortex,tip leakage vortex,trailing edge shedding vortex,and blade root horseshoe vortex.Combined with the pressure distribution,both the Q and λ2 criteria give reliable results of vortex identification.The cavitation causes an expansion of tip leakage vortex in the circumferential direction and decreases the intensities of tip separation vortex in the whole tip clearance area and tip leakage vortex in the cavitation area,and enhances the strength of tip leakage vortex in the downstream non-cavitation area.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51679052,51639004 and51809055)the Defense Industrial Technology Development Program(Grant No.JCKY2016604B001)the Natural Science Foundation of Heilongjiang Province of China(Grant No.E2018026)
文摘During ice-breaking navigation, a massive amount of crushed ice blocks with different sizes is accumulated under the hull of an ice-going ship. This ice slides into the flow field in the forward side of the podded propulsor, affecting the surrounding flow field and aggravating the non-uniformity of the propeller wake. A pulsating load is formed on the propeller, which affects the hydrodynamic performance of the podded propulsor. To study the changes in the propeller hydrodynamic performance during the ice podded propulsor interaction, the overlapping grid technique is used to simulate the unsteady hydrodynamic performance of the podded propulsor at different propeller rotation angles and different ice block sizes. Hence, the hydrodynamic blade behavior during propeller rotation under the interaction between the ice and podded propulsor is discussed. The unsteady propeller loads and surrounding flow fields obtained for ice blocks with different sizes interacting with the podded propulsor are analyzed in detail. The variation in the hydrodynamic performance during the circular motion of a propeller and the influence of ice size variation on the propeller thrust and torque are determined. The calculation results have certain reference significance for experiment-based research, theoretical calculations and numerical simulation concerning ice podded propulsor interaction.
基金Supported by the National Natural Science Foundation of China under Grant No.10702016
文摘A mathematical model of podded propulsors was established in order to investigate the influence of fins. The hydrodynamic performance of podded propulsors with and without fins was calculated, with interactions between propellers and pods and fins derived by iterative calculation. The differential equation based on velocity potential was adopted and hyperboloidal panels were used to avoid gaps between surface panels. The Newton-Raphson iterative procedure was used on the trailing edge to meet the pressure Kutta condition. The velocity distribution was calculated with the Yanagizawa method to eliminate the singularity caused by use of the numerical differential. Comparisons of the performance of podded propulsors with different fins showed that the thrust of propeller in a podded propulsor with fins is greater. The resistance of the pod is also reduced because of the thrust of the fin. The hydrodynamic performance of a podded propulsor with two fins is found to be best, the performance of a podded propulsor with one fin is not as good as two fins, and the performance of the common type is the worst.
基金supported by the Key R&D Program of Shandong Province,China(Grant No.2021ZLGX04)the National Natural Science Foundation of China(Grant No.52088102)the Shandong Provincial Natural Science Foundation(GrantNo.ZR2022ME147).
文摘Normally,small unmanned vessels used to clean floating litter on water adopt a paddle wheel as a propulsor to satisfy its shallow-draft requirements;however,this type of propulsor has bulky structures and inefficient propulsion.In this study,a novel tandem paddles propulsor(TPP)was developed,and its propulsion performance was analyzed and compared with that of a paddle wheel propulsor(PWP).Using the RNG k-εturbulence model and sliding grid technique,the hydrodynamic performance of the PWP was simulated in computational fluid dynamics(CFD)software to verify the reliability of the numerical method.Subsequently,the propulsion performances of the two types of propulsors were simulated with different immersion depths and advanced coefficients,and the differences in their mechanical characteristics and flow field evolution were discussed and compared.The results indicate that the proposed TPP generates 2.75 times more thrust and 1.99 times greater efficiency than the PWP,exhibiting superior propulsion capability in shallow-draft vessels.
文摘为合理地预测非定常力作用下泵喷推进系统的结构响应,流固耦合效应所产生的水动力阻尼不可忽略。不同模态的水动力阻尼量级决定了该模态对系统响应的贡献。针对泵喷推进系统的多模态水动力阻尼问题,首先基于计算流体动力学(computational fluid dynamics,CFD)和耦合有限法(finite element method,FEM),采用能量法对螺旋桨水动力阻尼特性展开数值研究。结果表明,能量法适用于水下叶轮机械水动力阻尼的研究,满足工程分析的需要。随后,基于能量法对简化泵喷推进系统多模态水动力阻尼特性展开数值研究,从非定常力做功的角度揭示影响水动力阻尼大小的主导因素。结果表明:转子主导的模态水动力阻尼较轴系主导模态的水动力阻尼高,转子轴系耦合模态水动力阻尼幅值大小则不固定,其主要取决于耦合系统中转子的振型及固有频率的大小;导管振动主导的模态水动力阻尼远高于定子振动带动导管运动的模态。水动力阻尼具有明显的模态依赖性,不同模态阻尼比幅值差距大,非定常力做功的影响显著高于固有频率。
基金Project supported by the "Knowledge-based Ship Design Hyper-Integrated Platform (KSHIP)"a key project of the Ministry of Education and the Ministry of Finance of China
文摘A podded propulsor in viscous flow is numerically simulated in this article. The region of fluid is divided into efficient calculation grids. The pressure and viscous force of blades, pod and strut are obtained as functions of an advance coefficient. The steady result is used as a base in the unsteady simulation to obtain a solution more quickly. The distributions of the thrust and torque fluctuations of the key blade in one revolution are obtained. The c^lculation results from the mixing plane on steady conditions are compared with those obtained from the sliding mesh model on unsteady conditions. The User-Defined Function （UDF） method is used to simulate the influence of ship hull on the non-uniform wake of the propeller.
