Blockage-Ratio Effect of a Bluff-Body Stabilized Flame on Aerosol Behavior of Carbonaceous (Soot) Nano-PM in a Combustor Burning Jet Propulsion Fuel

2016 ◽  
Author(s):  
Masoud Darbandi ◽  
Majid Ghafourizadeh ◽  
G E. Schneider
Keyword(s):  
Bluff Body ◽  
Blockage Ratio ◽  
Jet Propulsion ◽  
Ratio Effect

The effect of the blockage ratio on the blow-off limit of a hydrogen/air flame in a planar micro-combustor with a bluff body

2013 ◽  
Vol 38 (26) ◽  
pp. 11438-11445 ◽  
Author(s):  
Aiwu Fan ◽  
Jianlong Wan ◽  
Yi Liu ◽  
Boming Pi ◽  
Hong Yao ◽  
...  
Keyword(s):  
Bluff Body ◽  
Blockage Ratio ◽  
Micro Combustor

scholarly journals Research on Performance of H2Rich Blowout Limit in Bluff-Body Burner

2012 ◽  
Vol 2012 ◽  
pp. 1-28
Author(s):  
Hongtao Zheng ◽  
Yajun Li ◽  
Lin Cai
Keyword(s):  
Flow Velocity ◽  
Bluff Body ◽  
Negative Temperature ◽  
Main Stream ◽  
Blockage Ratio ◽  
Complete Extinction ◽  
Parabolic Function ◽  
Critical Ignition ◽  
Pdf Model ◽  
The Relationship

In order to investigate H2rich blowout limit at different blockage ratios and flow velocities, a CFD software FLUENT was used to simulate H2burning flow field in bluff-body burner, and the software CHEMKIN was adopted to analyze the sensitivity of each elementary reaction. Composition Probability Density Function (C-PDF) model was adopted to simulate H2combustion field in turbulence flame. The numerical results show that reactions R2 and R9 possess the largest positive and negative temperature sensitivity. Temperature has a very important influence on these two reactions. When equivalence ratio is 1, the mixture is most ignitable, and the critical ignition temperature is 1550 K. There should be an optimal blockage ratio which can stabilize the flame best. When the blockage ratio remains unchanged, the relationship between H2RBL and flow velocity is a logarithmic function. When the flow velocity remains unchanged, the relationship between H2RBL and blockage ratio is a parabolic function. A complete extinction requires three phases: the temperature sudden decline in the main stream, the energy dissipation from the recirculation zone to the main stream, and the complete extinction of the flame.

Numerical Analysis of Blockage Ratio Effect on a Portable Hydrokinetic Turbine

2016 ◽  
Author(s):  
Cosan Daskiran ◽  
Jacob Riglin ◽  
Alparslan Oztekin
Keyword(s):  
Free Stream ◽  
Numerical Study ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Power Coefficient ◽  
Stream Velocity ◽  
Blockage Ratio ◽  
Ratio Effect ◽  
Turbine Performance ◽  
Hydrokinetic Turbine

Three-dimensional steady state Computational Fluid Dynamics (CFD) analyses were performed for a pre-designed micro-hydrokinetic turbine to investigate the blockage ratio effect on turbine performance. Simulations were conducted using a physical turbine rotor geometry rather than low fidelity, simplified actuator disk or actuator lines. The two-equation k-ω Shear Stress Transport (SST) turbulence model was employed to predict turbulence in the flow field. The turbine performance at the best efficiency point was studied for blockage ratios of 0.49, 0.70 and 0.98 for three different free stream velocities of 2.0 m/s, 2.25 m/s and 2.5 m/s. Distinct blockage ratio results at a free stream velocity of 2.25 were compared to a previous numerical study incorporating the same rotor geometry within an infinite flowing medium. The pressure gradient between turbine upstream and turbine downstream for blocked channel flows elevated the turbine performance. The increment in blockage ratio from 0.03 to 0.98 enhanced power coefficient from 0.437 to 2.254 and increased power generation from 0.56 kW to 2.86 kW for the present study.

Testing Three-Dimensional Bluff-Body Models in a Low-Speed Two-Dimensional Adaptive Wall Test Section

1995 ◽  
Vol 117 (4) ◽  
pp. 546-551 ◽  
Author(s):  
D. Sumner ◽  
E. Brundrett
Keyword(s):  
Drag Coefficient ◽  
Test Section ◽  
Bluff Body ◽  
Three Dimensional ◽  
Correction Method ◽  
Blockage Ratio ◽  
Two Dimensional ◽  
Interference Effects ◽  
Low Speed ◽  
Straight Wall

Thin, sharp-edged disk models were evaluated in a low-speed two-dimensional adaptive flexible wall test section to determine the optimum adaptive wall testing environment for three-dimensional bluff-body models, by providing model testing recommendations for nominal solid blockage ratio and model span ratio. Drag coefficient measurements obtained under straight wall and adapted wall conditions showed that for a two-dimensional adaptive wall test section, the model span ratio imposes a more severe restriction upon model size than does the nominal solid blockage ratio. Minimum wall interference conditions were achieved with adapted walls for nominal solid blockage ratios less than 3 percent and model span ratios less than 21 percent, independent of the nominal test section aspect ratio, based on favorable comparison with previously-published experimental data. Data obtained under straight wall conditions confirmed that wall interference effects can only be neglected in conventional, straight-walled test sections for solid blockage ratios less than 0.5 percent and model span ratios less than 10 percent. The post-test boundary correction method of Maskell was successfully used to adjust the straight wall test section drag coefficient measurements of the larger models for wall interference effects, but no direct measurements of wall interference are used with this method. The results support the careful use of a two-dimensional wall adjustment strategy for three-dimensional nonlifting flows.

Effects of oxidizer flexibility and bluff-body blockage ratio on flammability limits of diffusion flames

2016 ◽  
Vol 178 ◽  
pp. 19-28 ◽  
Author(s):  
Islam A. Ramadan ◽  
Abdelmaged H. Ibrahim ◽  
Tharwat W. Abou-Arab ◽  
Sherif S. Rashwan ◽  
Medhat A. Nemitallah ◽  
...  
Keyword(s):  
Bluff Body ◽  
Diffusion Flames ◽  
Blockage Ratio ◽  
Flammability Limits

Jet Propulsion

2015 ◽  
Author(s):  
Nicholas Cumpsty ◽  
Andrew Heyes
Keyword(s):  
Jet Propulsion
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