scholarly journals Impact of the Thruster Jet Flow of Ultra-large Container Ships on the Stability of Quay Walls

Author(s):  
Taegeon Hwang ◽  
Gyeong-Seon Yeom ◽  
Minjang Seo ◽  
Changmin Lee ◽  
Woo-Dong Lee
Author(s):  
Yuki Maehara ◽  
Masatoshi Kondo ◽  
Minoru Takahashi

For the development of the liquid lithium (Li) jet target system for the boron neutron capture therapy (BNCT), the stability of the Li jet is important. The purpose of the present study is to investigate the characteristics of the disturbances and the droplet formation of a water jet flow at high velocity. The experimental studies for a water jet flow were performed to simulate the liquid Li jet flow. The nozzles in the experiment had a rectangular flow channel with the gap of 0.5 mm and the length of 10 mm and 70 mm. The water flow velocities in these nozzles were 5 m/s, 10 m/s or 15 m/s. The stability of the water jet flow was investigated by the observation of the surface disturbance using a high speed video camera. The formation of water droplet from the water jet flow was detected, and the characteristics of the droplet formation were analyzed using Phase Doppler Anemometry (PDA). Then, the surface disturbance of the jet flow was characterized by the characteristics of the droplet generation. In the experiment with 10mm length of nozzle, a lot of droplets are generated from the jet surface and the surface is considered to be unstable. On the other hand the smooth jet surface and the stable jet are made near nozzle outlet. In the experiment with 70mm length of nozzle, few droplets are generated from the surface of the jet and the surface of the jet is very smooth especially for the place near nozzle outlet. It was concluded that the droplet generation from the surface of the water jet was promoted by the distortion of the jet surface. Also the surfaces of the jet flow made by the nozzle having the length of 70 mm was smoother than those in the tests with the nozzle having the length of 10 mm. The large eddy in the flow must be dumped before the nozzle outlet because the turbulence was fully developed in the nozzle.


2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Bai-gang Mi ◽  
Hao Zhan

Frequent flight conflicts will be observed as the number of aircrafts increases, and such conflicts will cause unprecedented challenges in flight safety; thus, the flight characteristics of small aircrafts under the wake flow of a large airliner should be thoroughly analyzed. Combined with the sliding mesh technique, a computational fluid dynamics (CFD) method is proposed in this paper to simulate three wake flow patterns, i.e., wingtip vortex, jet flow, and propeller slipstream, and then, the static and dynamic derivatives that represent the stability of the fly wing under the wake flow are identified by using the least squares method. The results demonstrate that both the steady and unsteady aerodynamics of the fly wing are affected by wake flows: wingtip vortices increase the lift-to-drag ratio and considerably change the dynamic damping; jet flow reduces both the static and dynamic damping; and propeller slipstream leads to slow variations in the dynamic damping and decreases in the lift-to-drag ratio.


2013 ◽  
Vol 437 ◽  
pp. 47-50 ◽  
Author(s):  
Shi Nian Liu ◽  
Wei Su ◽  
Zeng Fu Wei

The nozzle is one of the critical parts in the dry-ice blasting system, spray nozzle's structure and the air supersonic free jet flow field take big influence on cleaning efficiency during the blasting process. Inner flow field of different size nozzles and the flow field of jet flow sprayed by nozzles were simulated with software Fluent, which obtained the distribution results of pressure and velocity of fluid. The result indicated that the supersonic underexpanded jet take place in the nozzle outlet and the shock wave is gained as the pressure at the nozzle exit is greater than the atmospheric pressure. With increasing of the nozzle size, the velocity decrease of airflow become slower, the shock wave transmission distance increase and deduce the stability of the jet flow.


2006 ◽  
Vol 18 (6) ◽  
pp. 064108 ◽  
Author(s):  
Radoslav German ◽  
Roger E. Khayat ◽  
Jing Kai Cui
Keyword(s):  
Jet Flow ◽  

2018 ◽  
Vol 1 (01) ◽  
pp. 11-15
Author(s):  
Kris Witono ◽  
Akhsanu Takwim

One of the factors that affect flame diffusion characteristics is the geometry of fuel nozzles in the installation of the combustion system. The nozzle shape greatly affects the turbulence that occurs between fuel and air. This process causes the formation of flow recirculation zones. This process thus produces homogeneous mixing and obtains near perfect combustion. The recirculation zones are zones arising from breaking the flow rate. So as to cause a vortex and backflow around the tip of the nozzle. It is this feedback which inhibits and simultaneously suppresses the flame so that the flow rate of the fuel mixture and the air is maintained lower or equal to the flame velocity. In this study, lip thickness variations in nozzles were used with swirls with variations of 0, 4, 8, 12, and 16 mm to determine flame stability of concentric jet flow diffusion. Fuel velocity and air are varied to obtain flame stability data. In addition, to support and reinforce the results obtained from this study, direct photograph and shadowgraph methods are used to obtain flow pattern visualization. The result of the research shows that the stability of flame concentric jet flow diffusion has increased along with the decreasing of lip thickness in nozzle. The largest flame stability area is obtained in 4 mm thick lip thickness.


Author(s):  
M. V. Kalashnik

The problem of the stability of a jet flow with a piecewise linear velocity profile in a stratified rotating atmosphere is considered. The linearized system of equations for perturbations is reduced to a single equation with respect to the amplitude of the longitudinal velocity component containing the turning points. In terms of Airy functions, an asymptotic solution of the equation is constructed that is valid for small values of the Rossby number. It is shown that the flow becomes unstable due to radiation of inertial-gravitational waves. An analytical expression is obtained for the growth rate of perturbations.


1982 ◽  
Vol 99 ◽  
pp. 605-613
Author(s):  
P. S. Conti

Conti: One of the main conclusions of the Wolf-Rayet symposium in Buenos Aires was that Wolf-Rayet stars are evolutionary products of massive objects. Some questions:–Do hot helium-rich stars, that are not Wolf-Rayet stars, exist?–What about the stability of helium rich stars of large mass? We know a helium rich star of ∼40 MO. Has the stability something to do with the wind?–Ring nebulae and bubbles : this seems to be a much more common phenomenon than we thought of some years age.–What is the origin of the subtypes? This is important to find a possible matching of scenarios to subtypes.


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