In this paper,a rotational supercavitating evaporator(RSCE)was at first modeled by means of theoretical analysis approach.The geometrical characteristics of supercavity in the modeled RSCE were then studied through nu...In this paper,a rotational supercavitating evaporator(RSCE)was at first modeled by means of theoretical analysis approach.The geometrical characteristics of supercavity in the modeled RSCE were then studied through numerical simulations.The current research objectives consist in determination of shape of the supercavitator(which in the plane of rotation generates supercavity occupying the most volume between blades),and location of the area suitable for steam extraction by revealing the inner structure of supercavity.Analytical analysis was performed by solving empirical equations for the shape of RSCE,through which an evaluation of two-dimensional relative position of supercavity trailing edge for different shapes of the supercavitator has been realized.Numerical simulation was then carried out,by numerically solving the unsteady Navier-Stokes equations in their conservation form coupled with the Rayleigh-Plesset cavitation and Shear-Stress Transport turbulence models,for verification of the results obtained from empirical equations.Despite unreliable assumption of applicability of empirical equations we have confirmed similarity of the supercavity shapes obtained by both methods for the same RSCE.Therefore,the shape of supercavitator calculated by using empirical equations is acceptable,which provides a simple but reliable approach for design of RSCE.The inner structure of supercavity obtained by numerical simulation has indicated position and parameters for steam extraction openings for further numerical and experimental studies on the performance of RSCE.Practical application of steam or gas extraction is suggested for solving of some problems associated with cavitating pumping of cryogenic liquid.展开更多
With the application of supercavitation effect, a novel device named rotational supercavitating evaporator(RSCE) was recently designed for desalination. In order to improve the blade shape of rotational cavitator in R...With the application of supercavitation effect, a novel device named rotational supercavitating evaporator(RSCE) was recently designed for desalination. In order to improve the blade shape of rotational cavitator in RSCE for performance optimization and then design three-dimensional blades, numerical simulations are conducted on the supercavitating flows(with cavitation number ranging from 0.055 to 0.315) around two-dimensional planar symmetric wedge-shaped cavitators with different wedge angles varied from 10 to 180 degrees. Proper numerical method for simulating supercavitating flows around planar symmetric cavitator is established, and assessment of k-ε-v2 -f turbulence model in simulating cavitating flows is conducted. It shows that the size of computational domain would affect the simulation result. Empirical formulae for supercavity dimensions about cavitation number at different wedge angles are obtained, which are of significant importance in the subsequent design of three-dimensional blade. The characteristics of resistance at different wedge angles are discussed, which, together with the characteristics of supercavity dimensions, play important roles in the optimal design of RSCE.展开更多
文摘In this paper,a rotational supercavitating evaporator(RSCE)was at first modeled by means of theoretical analysis approach.The geometrical characteristics of supercavity in the modeled RSCE were then studied through numerical simulations.The current research objectives consist in determination of shape of the supercavitator(which in the plane of rotation generates supercavity occupying the most volume between blades),and location of the area suitable for steam extraction by revealing the inner structure of supercavity.Analytical analysis was performed by solving empirical equations for the shape of RSCE,through which an evaluation of two-dimensional relative position of supercavity trailing edge for different shapes of the supercavitator has been realized.Numerical simulation was then carried out,by numerically solving the unsteady Navier-Stokes equations in their conservation form coupled with the Rayleigh-Plesset cavitation and Shear-Stress Transport turbulence models,for verification of the results obtained from empirical equations.Despite unreliable assumption of applicability of empirical equations we have confirmed similarity of the supercavity shapes obtained by both methods for the same RSCE.Therefore,the shape of supercavitator calculated by using empirical equations is acceptable,which provides a simple but reliable approach for design of RSCE.The inner structure of supercavity obtained by numerical simulation has indicated position and parameters for steam extraction openings for further numerical and experimental studies on the performance of RSCE.Practical application of steam or gas extraction is suggested for solving of some problems associated with cavitating pumping of cryogenic liquid.
基金supported by the National Natural Science Foundation of China(Grant No.51276046)Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20112302110020)
文摘With the application of supercavitation effect, a novel device named rotational supercavitating evaporator(RSCE) was recently designed for desalination. In order to improve the blade shape of rotational cavitator in RSCE for performance optimization and then design three-dimensional blades, numerical simulations are conducted on the supercavitating flows(with cavitation number ranging from 0.055 to 0.315) around two-dimensional planar symmetric wedge-shaped cavitators with different wedge angles varied from 10 to 180 degrees. Proper numerical method for simulating supercavitating flows around planar symmetric cavitator is established, and assessment of k-ε-v2 -f turbulence model in simulating cavitating flows is conducted. It shows that the size of computational domain would affect the simulation result. Empirical formulae for supercavity dimensions about cavitation number at different wedge angles are obtained, which are of significant importance in the subsequent design of three-dimensional blade. The characteristics of resistance at different wedge angles are discussed, which, together with the characteristics of supercavity dimensions, play important roles in the optimal design of RSCE.
