Investigation of the hydrodynamic impact of a planing small vessel on a water body

Рассмотрен экологический аспект использования маломерных глиссирующих судов. В статье представлен способ оценки характеристик потока, возмущённого движением глиссирующего судна. Способ основан на использовании численного метода гидродинамики. Выбраны параметры и зоны исследования потока вокруг корпуса рассмотренного судна, и разработана последовательность действий их определения. Проанализированы качественные картины изменения потока с ростом скорости глиссирующего судна с заданной геометрией, и выделены составляющие наиболее значимые составляющие. Оценены количественные характеристики возмущённого потока: вызванные скорости, расстояние от транца до точки зарождения системы волн, волновые характеристики. Оценка гидродинамического воздействия на водоём была проведена для двух притоков Волги – р.Керженец и р.Сура. Выполнено определение придонных касательных напряжений в выбранных водных объектах в их естественном и возмущённом присутствием судна состоянии. Проведено сравнение рассчитанных касательных напряжений с пороговыми значениями, что позволило оценить влияние движения маломерного судна на донный грунт. The ecological aspect of the use of small-sized planing vessels is considered. The article presents a method for assessing the characteristics of a flow disturbed by the movement of a planing vessel. The method is based on the use of the numerical method of hydrodynamics. The parameters and zones of the flow study around the hull of the vessel under consideration are selected, and a sequence of actions for their determination is developed. Qualitative patterns of flow changes with an increase in the speed of a planing vessel with a given geometry are analyzed, and the most significant components are identified. Quantitative characteristics of the perturbed flow are estimated: induced velocities, distance from the transom to the point of origin of the wave system, wave characteristics. The assessment of the hydrodynamic impact on the reservoir was carried out for two tributaries of the Volga - the Kerzhenets River and the Sura River. The determination of bottom tangential stresses in selected water bodies in their natural and disturbed state by the presence of the vessel was performed. The calculated tangential stresses were compared with threshold values, which made it possible to assess the impact of the movement of a small vessel on the bottom soil.

NUMERICAL INVESTIGATION OF INTERCEPTOR EFFECT ON SEA KEEPING BEHAVIOUR OF PLANING HULL ADVANCING IN REGULAR HEAD WAVES

In this paper an attempt has been made to assess the capability of numerical algorithm based on Reynolds Averaged Navier Stokes (RANS) for predicting the motion characteristics of the planing hull in calm water and regular waves. The focus of the present study is the impact of interceptors on the sea keeping quality of a planing vessel investigated through the application of numerical methods. The wave properties such as wavelength and wave height are taken into consideration to investigate the effect of wave steepness on vessel response. It is found that numerical data can efficiently simulate the motion attitude and the hydrodynamic characteristics of planing craft in regular head waves. The planing hull with and without interceptor fitted at the transom is simulated in numerical wave tank. The results show reduction in heave and pitch motions which gave favorable sea keeping behavior for the hull fitted with interceptor. The numerical solution is useful for the preliminary prediction of navigation safety during sailing.

Effects of Vertical Motions on Roll of Planing Hulls

Roll motion of a planing hull can be easily triggered at high speeds, causing a significant change in hydrodynamic pressure pattern, which can threaten the stability of the vessel. Modeling and investigating roll motion of a planing vessel may require a strong coupling between motions in vertical and transverse planes. In the present paper, we have used a mathematical model to analyze the roll of a planing hull by coupling surge, heave, pitch, and roll motions using 2D + T theory to study the effects of roll-induced vertical motions on roll coefficients and response. Mathematically computed forces and moments as well as roll dynamic response of the vessel are seen to be in fair quantitative agreement with experimentally measured values of previously published data. Using the 2D + T method, it has been shown that to model the roll of a planing hull at high speeds, we need to consider the effects of heave, pitch, and surge motions. Through our mathematical modeling, it is found that freedom in vertical motions increases time-dependent roll damping and added mass coefficients, especially at early planing speeds. The results of dynamic response simulations suggest that freedom in the vertical plane can decrease the roll response.