Experiment on Thin Structure Behavior of Explosion Flame Flow Field

2010 ◽  
Vol 44-47 ◽  
pp. 2793-2797
Author(s):  
Xian Feng Chen ◽  
Y. Zhang ◽  
M. Chen ◽  
Shao Feng Ren ◽  
Xiao L. Song
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Flame Structure ◽  
Propagation Mechanism ◽  
Flame Acceleration ◽  
Turbulent Transition ◽  
Schlieren Photography ◽  
Optical Measure ◽  
Air Explosion ◽  
And Control

To prevent and control fire and explosion disasters, the premixed methane-air explosion was performed under restricted condition. In the experiment, the high speed schlieren photography system was used to record the flame characteristics and propagation mechanism. At the same time the ion current probe was used to reveal the inner flame structure characteristics. Based on the images of High Speed Schlieren Photography, the flame acceleration and flame structure were discussed in detail. In addition, the flow field characteristic of explosion flame was disclosed clearly. The microscopic evolving process of laminar-turbulent transition was accomplished in the period of flame structure change. As an alternative observation and detect technique, the high speed schlieren photograph system was used to capture flame front microstructure dynamic process precisely. Based on burning chemical and explosive dynamics, the optical measure method can record flame dynamic behavior visually, which further helps to disclose flame microstructure characteristic and the inner dynamic mechanism.

scholarly journals Analysis and control of flow at suction connection in high-speed centrifugal pump

2017 ◽  
Vol 9 (1) ◽  
pp. 168781401668529 ◽  
Author(s):  
Wen-wu Song ◽  
Li-chao Wei ◽  
Jie Fu ◽  
Jian-wei Shi ◽  
Xiu-xin Yang ◽  
...  
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
High Speed ◽  
Internal Flow ◽  
Orifice Plate ◽  
Centrifugal Pumps ◽  
Pressure Area ◽  
Negative Effect ◽  
And Control ◽  
Experimental Data Analysis

The backflow vortexes at the suction connection in high-speed centrifugal pumps have negative effect on the flow field. Setting an orifice plate in front of the inducer is able to decrease the negative effect caused by backflow vortexes. The traditional plate is able to partially control the backflow vortexes, but a small part of the vortex is still in the inlet and the inducer. Four new types of orifice plates were created, and the control effects on backflow vortexes were analyzed. The ANSYS-CFX software was used to numerically simulate a high-speed centrifugal pump. The variations of streamline and velocity vectors at the suction connection were analyzed. Meanwhile, the effects of these plates on the impeller pressure and the internal flow field of the inducer were analyzed. Numerically, simulation and experimental data analysis methods were used to compare the head and efficiency of the high-speed pumps. The results show that the C-type orifice plate can improve the backflow vortex, reduce the low-pressure area, and improve the hydraulic performance of the high-speed pump.

3D Printing of Instantaneous Turbulent Flame Shapes, Experimentally Captured by 3D-Computer Tomography and Multi-Directional Schlieren Photography

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Yojiro Ishino ◽  
Naoki Hayashi ◽  
Yuta Ishiko ◽  
Ili Fatimah Bt Abd Razak ◽  
Yu Saiki ◽  
...  
Keyword(s):  
Computer Tomography ◽  
High Speed ◽  
Turbulent Flame ◽  
Flame Structure ◽  
Turbulent Flames ◽  
Density Level ◽  
Exit Velocity ◽  
Solid Models ◽  
Custom Made ◽  
Schlieren Photography

Non-scanning 3D-CT(Computer Tomography) technique employing a multi-directional quantitative schlieren photographic system(top-left picture) with flash light source, has been performed to obtain instantaneous density distributions of high-speed turbulent flames(for reference, the target flame of 8 m/s exit velocity is indicated in the right-top picture). For simultaneous schlieren photography, the custom-made 20-directional schlieren camera was constructed and used. The target turbulent flame is high-speed flames, anchored on the burner of a nozzle exit of 4.2 mm diameter. The image set of 20 directional schlieren images are processed by MLEM CT-algorithm to obtain the 3D reconstruction of instantaneous density distribution. The solid models(bottom picture) of threshold density level of 0.7 kg/m3 are 3D-printed as 4 times large size for detail observations. The average exit velocity of the propane-air mixture of equivalence ratio of 1.1 is set to be 10, 8, 6 and 4 m/s (models from left to right in the bottom picture). The solid models show the complicated shape of the high speed turbulent flames. The flame structure of higher speed flame has fine scale corrugations. This corresponds to the “corrugated flamelets regime” of the Borghi & Peters diagram well.

Research on Hydro-Dynamic of Column Body Water-Entry with Six-DOF at High-Speed

2014 ◽  
Vol 533 ◽  
pp. 40-43
Author(s):  
Shan Qi Wu ◽  
Xing Wu Kang
Keyword(s):  
Numerical Calculation ◽  
Flow Field ◽  
High Speed ◽  
Water Entry ◽  
Attitude Angle ◽  
Three Phase ◽  
Natural Cavitation ◽  
Six Dof ◽  
Phase Water ◽  
And Control

By using the commercial CFD software Fluent6.3, the three-phase (water, air, vapour) flow field with natural cavitation was established. The UDF(User Defined Function) was used to resolve and control the missiles movement. It realized the numerical calculation of unsteady high-speed water-entry flow field, which consider natural cavitation as well as the missiles multiple degree of free movement. In this paper, the missile high-speed water-entry flow field with different attitude angle were simulated and analyzed, and the influence of the attitude angle on the flow field were gained.

scholarly journals Cross-Flow Tidal Turbines with Highly Flexible Blades—Experimental Flow Field Investigations at Strong Fluid–Structure Interactions

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 797
Author(s):  
Stefan Hoerner ◽  
Iring Kösters ◽  
Laure Vignal ◽  
Olivier Cleynen ◽  
Shokoofeh Abbaszadeh ◽  
...  
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Cross Flow ◽  
Speed Ratio ◽  
Fluid Structure Interactions ◽  
Dimensional Parameter ◽  
Fluid Structure ◽  
Passive Flow Control ◽  
Tidal Turbines ◽  
Tidal Turbine

Oscillating hydrofoils were installed in a water tunnel as a surrogate model for a hydrokinetic cross-flow tidal turbine, enabling the study of the effect of flexible blades on the performance of those devices with high ecological potential. The study focuses on a single tip-speed ratio (equal to 2), the key non-dimensional parameter describing the operating point, and solidity (equal to 1.5), quantifying the robustness of the turbine shape. Both parameters are standard values for cross-flow tidal turbines. Those lead to highly dynamic characteristics in the flow field dominated by dynamic stall. The flow field is investigated at the blade level using high-speed particle image velocimetry measurements. Strong fluid–structure interactions lead to significant structural deformations and highly modified flow fields. The flexibility of the blades is shown to significantly reduce the duration of the periodic stall regime; this observation is achieved through systematic comparison of the flow field, with a quantitative evaluation of the degree of chaotic changes in the wake. In this manner, the study provides insights into the mechanisms of the passive flow control achieved through blade flexibility in cross-flow turbines.

Design and control of a high-speed direct-drive manipulator

1989 ◽  
Vol 27 (3) ◽  
pp. 375-394 ◽  
Author(s):  
K. YOUCEF-TOUMI ◽  
A. T. Y. KUO
Keyword(s):  
High Speed ◽  
Direct Drive ◽  
And Control
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