A new numerical method was developed for predicting the steady hydrodynamic performance of ducted propellers. A potential based surface panel method was applied both to the duct and the propeller, and the interaction ...A new numerical method was developed for predicting the steady hydrodynamic performance of ducted propellers. A potential based surface panel method was applied both to the duct and the propeller, and the interaction between them was solved by an induced velocity potential iterative method. Compared with the induced velocity iterative method, the method presented can save programming and calculating time. Numerical results for a JD simplified ducted propeller series showed that the method presented is effective for predicting the steady hydrodynamic performance of ducted propellers.展开更多
Horizontal axis tidal turbines have attracted more and more attentions nowadays, because of their convenience and low expense in construction and high efficiency in extracting tidal energy. The present study numerical...Horizontal axis tidal turbines have attracted more and more attentions nowadays, because of their convenience and low expense in construction and high efficiency in extracting tidal energy. The present study numerically investigates the flow motion and performance of a horizontal axis tidal turbine with a supporting vertical cylinder under steady current. In the numerical model, the continuous equation and incompressible Reynolds-averaged Navier-Stokes equations are solved, and the volume of fluid method is employed to track free surface motion. The RNG k-ε model is adopted to calculate turbulence transport while the fractional area/volume obstacle representation method is used to describe turbine characteristics and movement. The effects of installation elevation of tidal turbine and inlet velocity on the water elevation, and current velocity, rotating speed and resultant force on turbine are discussed. Based on the comparison of the numerical results, a better understanding of flow structure around horizontal axis tidal turbine and turbine performance is achieved.展开更多
The harm caused by bird swallowing itself mainly depends on the degree of engine damage after bird swallowing. Accurate and reliable results can be obtained through the whole machine experimental research, but the cos...The harm caused by bird swallowing itself mainly depends on the degree of engine damage after bird swallowing. Accurate and reliable results can be obtained through the whole machine experimental research, but the cost is relatively expensive. Therefore, the research work on bird swallowing mechanism, numerical simulation and analog evaluation is extremely necessary. In this paper, combined with the development requirements of a turbofan engine, the influence of bird swallowing on the performance of the whole machine is studied. Firstly, the strength simulation is carried out based on the bird swallowing condition, and the damage results of the engine after bird swallowing are obtained. Then, based on the calculated damage results, a concept and method of "equivalent damage" and "characteristic influence coefficient" are proposed, and the component characteristics are reconstructed based on the above concept and method. Then, the performance of the whole machine is simulated by using the reconstructed component characteristics, and the performance change results of the engine after bird swallowing are obtained. Finally, the evaluation results are verified by the bird swallowing test of the whole machine, trying to provide some experience reference for domestic research on the impact of bird swallowing on the performance of the whole machine.展开更多
基金Supported by the Open Research Foundation of State Key Laboratory of AUV,HEU under Grant No.2007015
文摘A new numerical method was developed for predicting the steady hydrodynamic performance of ducted propellers. A potential based surface panel method was applied both to the duct and the propeller, and the interaction between them was solved by an induced velocity potential iterative method. Compared with the induced velocity iterative method, the method presented can save programming and calculating time. Numerical results for a JD simplified ducted propeller series showed that the method presented is effective for predicting the steady hydrodynamic performance of ducted propellers.
基金funded by by the National Science Fund for Distinguished Young Scholars(Grant No.51425901)the National Natural Science Foundation of China(Grant Nos.51479053 and 51137002)+4 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK2011026)the 111 Project(Grant No.B2012032)the Specialized Research Funding for the Doctoral Program of Higher Education(Grant No.20130094110014)the Marine Renewable Energy Research Project of State Oceanic Administration(Grant No.GHME2013GC03)the Fundamental Research Funds for the Central University(Hohai University,Grant Nos.2013B31614 and 2014B04114)
文摘Horizontal axis tidal turbines have attracted more and more attentions nowadays, because of their convenience and low expense in construction and high efficiency in extracting tidal energy. The present study numerically investigates the flow motion and performance of a horizontal axis tidal turbine with a supporting vertical cylinder under steady current. In the numerical model, the continuous equation and incompressible Reynolds-averaged Navier-Stokes equations are solved, and the volume of fluid method is employed to track free surface motion. The RNG k-ε model is adopted to calculate turbulence transport while the fractional area/volume obstacle representation method is used to describe turbine characteristics and movement. The effects of installation elevation of tidal turbine and inlet velocity on the water elevation, and current velocity, rotating speed and resultant force on turbine are discussed. Based on the comparison of the numerical results, a better understanding of flow structure around horizontal axis tidal turbine and turbine performance is achieved.
文摘The harm caused by bird swallowing itself mainly depends on the degree of engine damage after bird swallowing. Accurate and reliable results can be obtained through the whole machine experimental research, but the cost is relatively expensive. Therefore, the research work on bird swallowing mechanism, numerical simulation and analog evaluation is extremely necessary. In this paper, combined with the development requirements of a turbofan engine, the influence of bird swallowing on the performance of the whole machine is studied. Firstly, the strength simulation is carried out based on the bird swallowing condition, and the damage results of the engine after bird swallowing are obtained. Then, based on the calculated damage results, a concept and method of "equivalent damage" and "characteristic influence coefficient" are proposed, and the component characteristics are reconstructed based on the above concept and method. Then, the performance of the whole machine is simulated by using the reconstructed component characteristics, and the performance change results of the engine after bird swallowing are obtained. Finally, the evaluation results are verified by the bird swallowing test of the whole machine, trying to provide some experience reference for domestic research on the impact of bird swallowing on the performance of the whole machine.
