Unsteady Supercavitated Motion of Bodies

Savchenko, Yu. N.; Semenenko, V. N.; Putilin, S. I.

doi:10.1615/interjfluidmechres.v27.i1.90

Cited by 15 publications

(6 citation statements)

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“…Each of the three references [16][17][18] provides some useful information for hydrodynamic design of underwater supercavitating high-speed vehicle. In this part, we draw on information provided by literature [16][17][18] and present comprehensively numerical and experimental results of such design. In order to check the validity of our proposed design, we planned carefully water tunnel model experiments and carried them out in NWPU high-speed water tunnel.…”

Section: Effects Of Gravitymentioning

confidence: 99%

“…It is usual to relate the change of deformation along cavity length to the square of the Froude number. The approximate formula of cavity axis slope caused by the gravity effect was investigated with the perturbation method by Savchenko and Semenenko 17 and Savchenko et al 18 who explained that the cavity axis bend increases according to the quadratic law. A schematic of cavity ordinate distortion in the gravitational field is shown in Figure 8.…”

Section: Effects Of Gravitymentioning

confidence: 99%

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Numerical investigation on the gas entrainment rate on ventilated supercavity body

Yang

Wen

et al. 2016

The Journal of Computational Multiphase Flows

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The supercavitation technique provides a means of significantly increasing the velocity of an underwater vehicle. This technique involves essentially the creation of stable supercavity shape. 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 model combined with the turbulence model and the full cavity model. The fundamental similarity parameters of ventilated supercavity flows that include cavitation number, Froude number Fr, entrainment rate C Q , and drag coefficient Cx are all investigated numerically in the case of steady flow and gravity field. We discuss the following simulations results in three parts: (1) the variations of the cavitation number and the supercavity's relative diameter with entrainment rate; (2) the drag coefficient versus the cavitation number; and (3) deformation of supercavity axis caused by gravitational effect for three different fixed three Froude numbers. In the full paper, we give the comparison results of the drag reduction ratio among numerical simulation and experiment conducted in hydrodynamic tunnel and towing tank, respectively. 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 is larger than 7.0. 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 ones and that the maximal value of the drag reduction ratio can be expected to reach the value of 90% compared with that of the condition of non-cavitation.

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Section: Effects Of Gravitymentioning

confidence: 99%

Section: Effects Of Gravitymentioning

confidence: 99%

Numerical investigation on the gas entrainment rate on ventilated supercavity body

Yang

Wen

et al. 2016

The Journal of Computational Multiphase Flows

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“…The process of interaction of the model and the cavity boundary is considered as unsteady planing of an elongated body along a curvilinear liquid surface. The arising forces are calculated on the base of the hypothesis of plane sections [9] . In this case the solution of the two-dimensional problem on immersion of the circular arc into the curvilinear free boundary is used.…”

Section: The Force By Planing Along the Cavity Boundarymentioning

confidence: 99%

Simulation of supercavitating vehicle steady motion

Tian¹,

An²,

Zhou³

2008

2008 International Conference on Machine Learning and Cybernetics

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The motion of supercavitating vehicle is complex, and the stability of supercavitating motion is an important problem. If the force of supercavitating vehicle is analyzed under the unstable motion, it is irrationality obviously. Therefore, it has more significance in engineering application that the reliability analysis of supercavitating vehicle under the steady motion. Taking this as a starting point, firstly, the predigested model of supercavitating vehicle is established, theory analysis is done by the actual status, the relation among every angle is obtained when the supercavitating vehicle moves steadily. Secondly, according to the theory analysis, the emulator of supercavitating vehicle moving steadily is programmed, then the simulation calculation is progressed, and from this simulation, the simulation result table is obtained when the supercavitating vehicle steadily moves, therefore, the force of the supercavitating vehicle is elicited from this table. The simulation result is treated, then the distributing and bound of every angle and every force is obtained, and based on this, the finite element analysis is done. The finite element analysis object is the tested model, the force and displacement state is obtained according to the calculation, then the reliability analysis is done with the monte-carlo method, finally, the reliability index is obtained.

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“…The experiments conducted at the Institute of Hydromechanics of the National Academy of Sciences of Ukraine [5][6][7][8] at speeds in the range from 400 m/s to 1000 m/s revealed self-stabilizing regimes of supercavitating motions when the gap h between the projectile and the cavity side is h < 0.15D where D is the diameter of the stern. At larger gaps, 0.15D < h < 0.3D, the rear part of an axisymmetric projectile periodically hits the cavity boundaries.…”

Section: Introductionmentioning

confidence: 99%

“…The dynamics of a supercavitating projectile and its stability were studied in a number of papers [5][6][7][8][9][10][11][12]. The mathematical models are based on a set of equations that include the hydrodynamic forces and moments acting on the projectile.…”

Section: Introductionmentioning

confidence: 99%

Impulsive Motion Inside a Cylindrical Cavity

Savchenko

Semënov

2020

Mathematics

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Experimental studies of supercavitating models moving at speeds in the range from 400 m/s to 1000 m/s revealed a regime of bouncing motion, in which the rear part of an axisymmetric body periodically bounces against the free boundaries of the supercavity. The impulsive force generated by the impacts is the main concern in this paper. The analysis is performed in the approximation of two-dimensional potential flow of an ideal and incompressible liquid with negligible surface tension effects. The primary interest of the study is to determine the added mass taking into account the shape of the cavity. The theoretical study is based on the integral hodograph method, which makes it possible to obtain analytic expressions for the flow potential and for the complex velocity in an auxiliary parameter plane and obtain a parametric solution to the problem. The problem is reduced to a system of two integro-differential equations in two unknowns: the velocity magnitude on the cavity boundary and the slope of the velocity angle to the body. The equations are solved numerically using the method of successive approximations. The obtained results show that the added mass of an arc impacting a cylindrical cavity depends heavily on the arc angle. As the angle tends to zero or the radius of the cavity tends to infinity, the obtained solution predicts the added mass corresponding to a plate impacting a flat free surface.

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Unsteady Supercavitated Motion of Bodies

Cited by 15 publications

References 0 publications

Numerical investigation on the gas entrainment rate on ventilated supercavity body

Numerical investigation on the gas entrainment rate on ventilated supercavity body

Simulation of supercavitating vehicle steady motion

Impulsive Motion Inside a Cylindrical Cavity

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