Experiments on interaction between current-induced vibration and scour of submarine pipelines on sandy bottom

In order to understand the dynamic behavior of submarine pipelines exposed to current and the mechanism of the interaction between current-induced vibration and scour of pipelines on a sandy bottom, an experimental investigation is conducted with a small scale model A test model which can be tested in the flume is set up by taking into account the typical working conditions of the pipelines and by applying the similarity theory. The interactions between the shape of the scour hole and the behavior of the pipeline as well as the flow patterns of the current are detailed, and the interaction mechanism outlined. The effect of vibration of the pipeline on the development of dynamic scour at different stages is found out. The proposed experimental method and test results provide an effective means for design of marine pipelines against scouring.

海流-管道-海床之间动力相互作用的量纲分析及实验模拟装置研制=Dimensional Analysis and Experimental Apparatus on Interaction between Ocean Current-Pipeline and Seabed

海底管道涡激振动和管道周围海床冲刷是海流--管道--海床之间复杂的动力耦合问题.文章应用量纲分析方法对海流、管道与海床之间的动力耦合作用进行了分析,确定了在实验模拟中应遵循的相似准则.在此基础上,研制了一套能模拟海流、海床与海底管道之间相互作用的实验模拟装置.初步实验结果表明文中研制的实验模拟装置能够模拟典型海洋环境下海底管道的涡激振动和管道周围海床冲刷等问题.

Heating characteristics of blunt swept fin-induced shock wave turbulent boundary layer interaction

An experimental study was conducted on shock wave turbulent boundary layer interactions caused by a blunt swept fin-plate configuration at Mach numbers of 5.0, 7.8, 9.9 for a Reynolds number range of (1.0.similar to 4.7) x 10(7)/m. Detailed heat transfer and pressure distributions were measured at fin deflection angles of up to 30 degrees for a sweepback angle of 67.6 degrees. Surface oil flow patterns and liquid crystal thermograms as well as schlieren pictures of fin shock shape were taken. The study shows that the flow was separated at deflection of 10 degrees and secondary separation were detected at deflection of theta greater than or equal to 20 degrees. The heat transfer and pressure distributions on flat plate showed an extensive plateau region followed by a distinct dip and local peak close to the fin foot. Measurements of the plateau pressure and heat transfer were in good agreement with existing prediction methods, but pressure and heating peak measurements at M greater than or equal to 6 were significantly lower than predicted by the simple prediction techniques at lower Mach numbers.

Effect of current on the evolution of a solitary wave

In this paper, the effect of current on the evolution of a solitary wave is studied. The governing equation in the far field, KdV equation with variable coefficients, is derived. A solitary wave solution is obtained. The fission of a solitary wave is discussed, and the fissible region on the Q～h2-plane and the criterion of the number of the solitary waves after fission are found.

Interaction of oblique incident electromagnetic wave with relativistic ionization front

Interactions of oblique incident probe wave with oncoming ionization fronts have been investigated using moving boundary conditions. Field conversion coefficients of reflection, transmission and magnetic modes produced in the interactions are derived. Phase matching conditions at the front and frequency up-shifting formulas for the three modes are also presented.

Studies on threshold current densities for convulsion of fish using a square wave stimulator

The threshold current densities and voltage tensions (body voltages) between the head and tail for bringing about distinct reactions in Salmo irideus, Cyprinus Carpio, Tinea tinca, Gasterosteus aculeatus and Salmo fario were studied. In C. carpio and T. tinca, absolute current densities required decreased with increase in length of fish. Threshold current densities for different reactions of fish increased with rise in water temperature and conductivity of surrounding medium except in case of T. tinca where low current densities were sufficient in higher conductivity of water. Impulse D.C. was superior to continuous D.C. Better effect was noticed in fishes in lower current densities when their bodies were parallel to the lines of current conduction.

Can fundamental shock-wave/boundary-layer interaction research be relevant to inlet aerodynamics?

The important influence of shock waves on supersonic inlet performance has led to much time and effort being expended in the area of shock wave/boundary layer interaction research (SWBLI) and SWBLI control. In this short review, the impact of SWBLIs on supersonic inlet aerodynamic research is discussed and is contrasted with fundamental SWBLI research. Inlet research focussed on internal flow performance is reviewed, based on the salient results, conclusions, and the limitations of such work. The role of fundamental SWBLI research in relation to supersonic inlet research is considered, and the possible positive impact of improving the link between fundamental SWBLI research and inlet design is considered. A simple flow-field is discussed which is thought to be able to simulate at least some more of the flow physics found in a typical inlet. A brief review of real inlet parameters is then given to help determine appropriate fundamental experimental parameters such as incoming Mach number, incoming boundary-layer thickness and subsonic difiuser angle. Copyright © 2012 by N. Titchener, H. Babinsky, and E. Loth.

Control of a shock-wave/boundary-layer interaction and subsequent subsonic diffuser using a combination of vortex generators and bleed

An experimental investigation has been undertaken in which vortex generators (VGs) have been employed to inhibit boundary-layer separation produced by the combined adversepressure- gradient of a terminal shock-wave and subsonic diffuser. This setup has been developed as part of a program to produce a more inlet relevant flow-field using a small-scale wind tunnel than previous studies. The resulting flow is dominated by large-scale separation, and as such, is thought to be a good test-bed for flow control. In this investigation, VGs have been added to determine their potential for shock-induced separation mitigation. In line with previous studies, it was observed that the application of VGs alone was not able to significantly alleviate separation overall, because enlarged corner separations was observed. Only when control of the corner separations using corner bleed was employed alongside centre-span control using VGs was a significant improvement in both wall pressure recovery (6% increase) and stagnation pressure recovery (2.4% increase) observed. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc.