Flow Visualization and analysis by PIV Measurement System using Micro-bubbles as Tracer in Ship Model Basin-Measurement in Still Water and Regular Waves -
To measure and analyze the flow around ship model, use of micro-babbles as tracer is proposed here. The system has two high speed cameras for stereo photography with continuous laser light sheet. Using continuous laser light sheet flow around ship can be observed directly. To make validation of the present system flow analysis of uniform flow and regular waves in ship model basins is carried out. From the comparison between flow velocity analyzed by the present system and that measured by current meter in different three ship model basins, it is found that the correlation factors of the basins are over 0.99 for flow velocity of ship advance direction. In regular waves the trajectory of the wave motion is compared to small amplitude wave theory and analyzed value. From the comparison it is found that the agreement is well for different wave frequencies. Continuously, flow measurement using a ship model of large tanker has performed in still water and in regular head waves. From the analysis it is found that the difference of the flow vector between still water and regular head waves can be evaluated qualitatively. Thereafter to understand the flow around propeller the tank tests in self propelling condition of the ship model are performed. From the comparison between the tests with propeller and without propeller, the effect of propeller suction is revealed. From the various comparisons the effectiveness of the PIV system using micro-bubbles to obtain flow information around ship is confirmed.
Energy-Saving Principle of the IHIMU Semicircular Duct and Its Application to the Flow Field Around Full Scale Ships
INUKAI Yasuhiko : Naval Architect, Hydrodynamics Engineering, Ship & Offshore Basic Design Department, IHI Marine United Inc. KANEKO Tadaaki : Naval Architect, Hydrodynamics Engineering, Ship & Offshore Basic Design Department, IHI Marine United Inc. NAGAYA Shigeki : Doctor of Engineering, Senior Researcher, Ship & Marine Technology Department, Products Development Center, Corporate Research & Development OCHI Fumitoshi : Experiments Technology Department, Research & Development Divisions, IHI Inspection & Instrumentation Co., Ltd.
Exponential stabilization of an axially moving string with geometrical nonlinearity by linear boundary feedback
This paper addresses the vibration suppression problem of an axially moving string using boundary control. Taking into account large transverse motion of the string via the second-order component of Lagrangian strain, a nonlinear oscillation equation is derived for the problem by employing the Hamilton's Principle. Direct Lyapunov method is then adopted to demonstrate that a linear boundary control of negative speed feedback ensures the vibration response of the moving string exponentially stable. The main contributions are a new stability condition in terms of controller gain parameter, and a detailed demonstration on the equilibrium condition at the boundary where the control is applied.