Supercavitation is a revolutionary technique to achieve high drag reduction for underwater vehicle.It can help us to break through the conventional speed barrier.This article presents a numerical algorithm for ventila...Supercavitation is a revolutionary technique to achieve high drag reduction for underwater vehicle.It can help us to break through the conventional speed barrier.This article presents a numerical algorithm for ventilated supercavitation flow field based on mixture multiphase flow model,briefs the calculation results and compares them with that tested in high-speed water tunnel and towing tank.The mathematical model,its numerical calculation method,computational region and boundary conditions are discussed in detail.Some pertinent nondimensional parameters about the ventilated supercavitation,such as geometrical configuration of supercavity,drag coefficient and ventilation rate are investigated.Reynolds number is selected to predict gas ventilation rate instead of Froude number.Finally,based on the test and simulation results,a semi-empirical formula of the ventilation rate estimation suitable for different conical angle caritators is proposed.展开更多
For some vehicles travelling through water, it is advantageous to cover the vehicle in a supercavity for the sake of reducing the drag acting on it. The method of artificial ventilation is most effective for generatin...For some vehicles travelling through water, it is advantageous to cover the vehicle in a supercavity for the sake of reducing the drag acting on it. The method of artificial ventilation is most effective for generating and dominating the supercavity. This paper focuses on the numerical simulation of flow field around three dimensional body. The method is based on the multiphase computational fluid dynamics （CFD） model combined with the turbulence model and the full cavity model. The flow field of cavity is simulated by solving the compressible Navier-Stokes equations. The fundamental similarity parameters of ventilated supercavitaty flows that include cavitation number, Froude number, ventilation rate and drag coefficient are all investigated numerically in the case of steady flow and gravity field. We discuss the following simulations results in section 3： The variations of the cavitation number and the supercavity＇s relative diameter with ventilation rate （subtopic 3.1）; The drag coefficient versus the cavitation number （subtopic 3.2）; Deformation of supercavity axis caused by gravitational effect for three different fixed Froude numbers-2.8, 3.4, 4.2 （subtopic 3.3）. In subtopic 3.2, we give the comparison results of the drag reduction ratio among numerical simulation and experiment conducted in hydrodynamic tunnel and towing tank respectively. In subtopic 3.3, we summarize our discussion of gravitational effect on the axis deformation of supercavity as follows： In the case of smaller Froude number, the inclination of the cavity axis increases monotonously with increasing horizontal length, and reaches its maximal value at the end of supercavity; This deformation can be almost completely negligible when the Froude number Fr〉7. The comparisons with the experimental data in the hydrodynamic tunnel and the towing tank indicate that the present method is effective for predicting the flows around ventilated supercavity; that the numerical results is in good agreement with the experimental one展开更多
基金Sponsored by National Basic Research Programof China(K1804061802)
文摘Supercavitation is a revolutionary technique to achieve high drag reduction for underwater vehicle.It can help us to break through the conventional speed barrier.This article presents a numerical algorithm for ventilated supercavitation flow field based on mixture multiphase flow model,briefs the calculation results and compares them with that tested in high-speed water tunnel and towing tank.The mathematical model,its numerical calculation method,computational region and boundary conditions are discussed in detail.Some pertinent nondimensional parameters about the ventilated supercavitation,such as geometrical configuration of supercavity,drag coefficient and ventilation rate are investigated.Reynolds number is selected to predict gas ventilation rate instead of Froude number.Finally,based on the test and simulation results,a semi-empirical formula of the ventilation rate estimation suitable for different conical angle caritators is proposed.
基金supported by National Defense Basic Research Foundation of China(No.K1800060604).
文摘For some vehicles travelling through water, it is advantageous to cover the vehicle in a supercavity for the sake of reducing the drag acting on it. The method of artificial ventilation is most effective for generating and dominating the supercavity. This paper focuses on the numerical simulation of flow field around three dimensional body. The method is based on the multiphase computational fluid dynamics （CFD） model combined with the turbulence model and the full cavity model. The flow field of cavity is simulated by solving the compressible Navier-Stokes equations. The fundamental similarity parameters of ventilated supercavitaty flows that include cavitation number, Froude number, ventilation rate and drag coefficient are all investigated numerically in the case of steady flow and gravity field. We discuss the following simulations results in section 3： The variations of the cavitation number and the supercavity＇s relative diameter with ventilation rate （subtopic 3.1）; The drag coefficient versus the cavitation number （subtopic 3.2）; Deformation of supercavity axis caused by gravitational effect for three different fixed Froude numbers-2.8, 3.4, 4.2 （subtopic 3.3）. In subtopic 3.2, we give the comparison results of the drag reduction ratio among numerical simulation and experiment conducted in hydrodynamic tunnel and towing tank respectively. In subtopic 3.3, we summarize our discussion of gravitational effect on the axis deformation of supercavity as follows： In the case of smaller Froude number, the inclination of the cavity axis increases monotonously with increasing horizontal length, and reaches its maximal value at the end of supercavity; This deformation can be almost completely negligible when the Froude number Fr〉7. The comparisons with the experimental data in the hydrodynamic tunnel and the towing tank indicate that the present method is effective for predicting the flows around ventilated supercavity; that the numerical results is in good agreement with the experimental one
