On the problem of simulation of influence flooded compartment on the dynamics of the ship's navigation.

В статье рассматривается возможность применения имеющихся в настоящее время решений задачи о влиянии динамического переливания жидкости в аварийных отсеках 2-й категории или успокоительных цистернах на качку судна в системах имитационного моделирования динамики плавания аварийных судов. Существующие решения получены в интересах исследования качки в частотной области и формально могут быть перенесены во временну́ю область, отвечающую существованию имитационных моделей, посредством обратного преобразования Фурье, что связано с определенными затруднениями. В работе показано, что при определенной формулировке гидродинамической задачи о колебаниях жидкости в отсеке или цистерне во временно́й области могут быть использованы непосредственно исходные уравнения. Выполнены расчеты, подтверждающие корректность такого подхода с позиций обеспечения устойчивости решения задачи и физической адекватности результатов реально наблюдаемым процессам. The article discusses the possibility of using the currently available solutions to the problem of the effect of dynamic fluid overflow in emergency compartments of the 2nd category or damping tanks on the pitching of a ship in systems for simulation of the dynamics of navigation of damaged ships. The existing solutions were obtained in the interests of studying the pitching in the frequency domain and can formally be transferred to the time domain corresponding to the existence of simulation models by means of the inverse Fourier transform, which is associated with certain difficulties. It is shown in the work that with a certain formulation of the hydrodynamic problem of fluid oscillations in a compartment or tank in the time domain, the original equations can be used directly. Calculations have been performed that confirm the correctness of this approach from the standpoint of ensuring the stability of the solution to the problem and the physical adequacy of the results to the actually observed processes.

A COMPARISON STUDY ON THE RESISTANCE CALCULATION OF PLANNING BOAT

Calculation of the resistance and trim of highspeed boat at planning regime is a complex hydrodynamic problem. At the planning regime, with the aid of lifting force, the boat is lifted over the water surface with high trim angle. Many methods have been applied to calculate the resistance and the trim of the high-speed boat at this planning regime. This paper will study the two typical methods, the first one is empirical method by Savitsky [1] and the second one is the computational fluid dynamic method (CFD). The calculation results of two methods are compared with experimental results.

STUDY OF STABILITY OF A TANK-CONTAINER WITH A FILLED LIQUID AT LONGITUDINAL OSCILLATIONS

The effect of the oscillating fluid on the dynamic stability of the tank-container is studied at different filling capacities. The main method for studying the dynamic stability of a railway platform with a tank- container in theoretical calculations is the method of full integration, i.e. all the solutions of the system of differential equations describing the movement of the tank-container with liquid are found, and from them a conclusion is made on the stability of the movement. The study of the longitudinal vibrations of the liquid and the tank-container is considered at various impact speeds and without taking into account the galloping angle. The solution of the system of differential equations reduces to the solution of the hydrodynamic problem.

Applying the method of plane sections for evaluating the parameters of flight vehicles under multiphase flow

Numerical simulation of the underwater motion of flight vehicles launched from underwater is performed. The updated method of plane sections is used to determine the hydrodynamic parameters of flight vehicles under multiphase flow. Hydrodynamic loading can be evaluated through the determination of nonstationary boundaries of a gas cavity and the linear load on the water-flown aft. By the method of plane sections, the 3D boundary value problem of the cavitational flow of a flight vehicle at an attack angle resolves itself into a plane hydrodynamic problem, separate for each section of the cavity. The predicted results are compared with the experimental data. Validation and verification were performed by comparing the analysis results with the experimental data. The applicability of the method of plane sections to the determination of the hydrodynamic parameters of flight vehicles under multiphase flow is demonstrated.

On the hydrodynamics of three in-line square cylinders in a uniform flow

In this paper, is the hydrodynamics of three in-line square cylinders in a uniform flow, where the gap between two neighboring square cylinders is equivalent is under investigation. The fluid dynamics around those multiple bluff bodies, including time-mean drag coefficients, time-mean lift coefficients and Strouhal numbers, are considered at the Reynolds number [Formula: see text]. Through numerically solving the nonlinear hydrodynamic problem, we show that the drag force acting on the first square cylinder is always larger than that acting on the remaining two square cylinders. From the perspective of wake structures, with keeping the increase of the gap between two neighboring square cylinders, the wake structures become much more complicated, including attachment of shear layer, interaction between shear layer and vortex, interaction between vortex and vortex, etc. Moreover, the Strouhal number of three square cylinders are approximately equaled when the dimensionless gap between two neighboring square cylinders is less than 2.