Velocity Measurements of Vortex Breakdown in an Enclosed Cylinder

2001 ◽  
Vol 123 (3) ◽  
pp. 604-611 ◽  
Author(s):  
Kazuyuki Fujimura ◽  
Hiroaki Yoshizawa ◽  
Reima Iwatsu ◽  
Hide S. Koyama ◽  
Jae Min Hyun
Keyword(s):  
Laser Doppler Velocimetry ◽  
Vortex Breakdown ◽  
Rotating Disk ◽  
Velocity Fields ◽  
Laser Doppler ◽  
Velocity Measurements ◽  
Experimental Apparatus ◽  
Breakdown Phenomenon ◽  
Component Velocity ◽  
Flow Visualizations

Experimental measurements were carried out of three-component velocity fields inside a cylindrical container. Flow was driven by the rotation of the top endwall disk. The purpose of the precision laser-Doppler velocimetry measurements was to describe the velocity characteristics pertinent to the vortex breakdown phenomenon. A turntable experimental apparatus was fabricated. Extensive laser-Doppler measurements, as well as flow visualizations, were made for the aspect ratio 1.50 and 2.50, and the Reynolds number ranges 0.99×103-2.20×103. The measured meridional velocities were found to be consistent with the prior visualization studies. The characteristic changes in swirling motions in the vicinity of vortex breakdown bubble are depicted. Detailed flow patterns near the rotating disk are constructed by using the experimental data.

scholarly journals Laser Doppler Velocimetry Measurements in Turbulent Gaseous Mixing Induced by the Richtmyer–Meshkov Instability: Statistical Convergence Issues and Turbulence Quantification

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Ghazi Bouzgarrou ◽  
Yannick Bury ◽  
Stéphane Jamme ◽  
Laurent Joly ◽  
Jean-Francois Haas
Keyword(s):  
Shock Wave ◽  
Velocity Field ◽  
Laser Doppler Velocimetry ◽  
Statistical Convergence ◽  
Laser Doppler ◽  
Reflected Shock Wave ◽  
Doppler Velocimetry ◽  
Statistical Characterization ◽  
Stage Of Development ◽  
Experimental Apparatus

A statistical characterization of the turbulent flow produced in a vertical shock tube dedicated to the study of the Richtmyer–Meshkov instability (RMI) is carried out using laser Doppler velocimetry (LDV), time-resolved Schlieren images, and pressure histories. The time evolution of the phase-averaged velocity field and the fluctuating velocity levels produced behind the shock wave (SW) are first investigated for different configurations of a pure air homogeneous medium. This allows us to determine the background turbulence of the experimental apparatus. Second, the RMI-induced turbulent air/sulfur hexafluoride (SF6) mixing zone (TMZ) is studied both in its early stage of development and after its interaction with a reflected shock wave (RSW) (reshock phenomenon). Here, the gaseous interface is initially produced by a thin nitrocellulosic membrane trapped between two grids. One of the most consistent issues regarding such a process is the generation of a large number of fragments when the incident SW crosses the interface. These fragments are likely to corrupt the optical measurements and to interact with the flow. This work seeks to clarify the influence of these fragments on the statistical determination of the velocity field. In particular, it is shown that statistical convergence cannot be achieved when the fragments are crossing the LDV measurement volume, even if a significant number of identical experiments are superimposed. Some specific locations for the LDV measurements are, however, identified to be more favorable than others in the air/SF6 mixing configuration. This finally allows us to quantify the surplus of turbulence induced by the reshock phenomenon.

Study on Multi-Point Velocity Measurements of Laser Doppler Velocimetry Based on Dual-Core Photonic Crystal Fiber

2015 ◽  
Vol 35 (11) ◽  
pp. 1112003
Author(s):  
黄雪峰 Huang Xuefeng ◽  
赵冠军 Zhao Guanjun ◽  
李盛姬 Li Shengji ◽  
郭枫 Guo Feng ◽  
郑光华 Zheng Guanghua ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Photonic Crystal Fiber ◽  
Laser Doppler Velocimetry ◽  
Laser Doppler ◽  
Doppler Velocimetry ◽  
Velocity Measurements ◽  
Crystal Fiber ◽  
Point Velocity ◽  
Dual Core

Flow Field Measurements of an Unsteady Reacting Muzzle Exhaust Flow

1983 ◽  
Vol 105 (4) ◽  
pp. 884-888 ◽  
Author(s):  
G. Klingenberg ◽  
H. Mach ◽  
G. Smeets
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Laser Doppler Velocimetry ◽  
Field Measurements ◽  
Laser Doppler ◽  
Temperature Measurements ◽  
Doppler Velocimetry ◽  
Velocity Measurements ◽  
Lateral Velocity ◽  
Schlieren Photography

The events associated with the discharge of a 20-mm caliber weapon have been examined in detail in order to identify and understand important features of the reacting gun muzzle flow field. The diagnostics applied involves shadowgraph and Schlieren photography, invasive pressure probes, spectroscopy for temperature measurements and Laser-Doppler velocimetry for velocity measurements. Emphasis has been on velocity measurements using two setups to determine both the axial and lateral velocity components throughout the muzzle flow field. The data clearly demonstrate the complexity of the processes involved in the unsteady flow expansion of the gun muzzle exhaust flow.

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