Applicability of Femtosecond Laser Electronic Excitation Tagging in Combustion Flow Field Velocity Measurements

2018 ◽  
Vol 72 (12) ◽  
pp. 1807-1813 ◽  
Author(s):  
Dayuan Zhang ◽  
Bo Li ◽  
Qiang Gao ◽  
Zhongshan Li
Keyword(s):  
Flow Field ◽  
Femtosecond Laser ◽  
Electronic Excitation ◽  
Flow Fields ◽  
Velocity Measurements ◽  
Molecular Tagging Velocimetry ◽  
Molecular Tagging ◽  
Field Velocity ◽  
Combustion Flow ◽  
Better Than

Femtosecond laser electronic excitation tagging (FLEET) is a molecular tagging velocimetry technique that can be applied in combustion flow fields, although detailed studies of its application in combustion are still needed. We report the applicability of FLEET in premixed CH4–air flames. We found that FLEET can be applied in all of the combustion areas (e.g., the unburned region, the burned region and the reaction zone). The FLEET signal in the unburned region is significantly higher than that in the burned region. This technique is suitable for both lean and rich CH4–air combustion flow fields and its performance in lean flames is better than that in rich flames.

Flow-field velocity measurements for nonisothermal systems

1991 ◽  
Author(s):  
Edward J. Johnson, Jr. ◽  
Paul V. Hyer ◽  
Paul W. Culotta ◽  
Ivan O. Clark
Keyword(s):  
Flow Field ◽  
Velocity Measurements ◽  
Field Velocity

scholarly journals Temperature measurement in combustion flow field with femtosecond laser-induced filament

2020 ◽  
Vol 69 (23) ◽  
pp. 234207
Author(s):  
Shuai-Yao Li ◽  
Da-Yuan Zhang ◽  
Qiang Gao ◽  
Bo Li ◽  
Yong He ◽  
...  
Keyword(s):  
Flow Field ◽  
Femtosecond Laser ◽  
Temperature Measurement ◽  
Combustion Flow

scholarly journals WAVE INDUCED VELOCITIES CLOSE TO A RIPPLED BED

1982 ◽  
Vol 1 (18) ◽  
pp. 21
Author(s):  
C.G. Du Toit
Keyword(s):  
Flow Field ◽  
Oscillatory Flow ◽  
Flow Fields ◽  
Flow Reversal ◽  
Velocity Measurements ◽  
Rippled Beds ◽  
Wave Induced ◽  
Rippled Bed

The results are reported of velocity measurements in oscillatory flow over rippled beds. Velocities were measured with a laserdoppler anemometer in both an oscillating tray rig and an oscillatory flow U-tube. Both self-formed and artificial ripples were examined. The results obtained in the two test rigs were compared and it was concluded that the flow fields obtained in the two cases were dynamically similar. Measurements of the flow field clearly showed the formation, growth and ejection of vortices, as well as a strong surge of fluid over the ripples during and after flow reversal.

Experimental Study of Humid Air Diffusion Flames in HAT Cycle

2007 ◽  
Author(s):  
Bing Ge ◽  
Shu-Sheng Zang ◽  
Xin Gu
Keyword(s):  
Flow Field ◽  
Flow Region ◽  
Flow Fields ◽  
Temperature Fields ◽  
Reversed Flow ◽  
Humid Air ◽  
Turbulent Diffusion Flame ◽  
Dry Air ◽  
Humid Air Combustion ◽  
Combustion Flow

Combustion with humid air is a key process of humid air turbine (HAT) cycles. Many studies have been undertaken to understand the influence of moisture in air on combustion fields. This study focuses on investigating the differences between the propane/humid air turbulent diffusion flame in a bluff-body burner and the same flame with normal dry air. The moisture levels were achieved by injecting steam into dry air. Particle image velocimetry was used to study the velocity fields experimentally in the humid reactive burner flow and the equivalent non-humid flow. The temperature fields of flames were measured using high temperature thermocouples, and the NO distributions were obtained with gas detection instruments. The results show that although humid air reactive flow fields are similar to the non-humid flow fields in general, there are some differences in the humid air combustion flow field comparing to the same combustion flow field with normal dry air: the center of the reversed-flow region goes forward; the dimension of the reversed-flow region is smaller. An analysis of NO formation revealed NO reduction of humid air flames due to the presence of steam. It is suggested that humid air combustion is helpful to shorten the axial length of combustor, and reduce the formation of pollution.

Spatial Structure of Negative ∂u˜/∂y in a Low Rθ Turbulent Boundary Layer

1998 ◽  
Vol 120 (4) ◽  
pp. 772-777 ◽  
Author(s):  
Joseph C. Klewicki ◽  
Rodney B. Hill
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Plate Boundary ◽  
Flow Fields ◽  
Wall Region ◽  
Spatial Correlations ◽  
Molecular Tagging Velocimetry ◽  
Molecular Tagging ◽  
Multiple Line ◽  
Layer Velocity

Multiple line Molecular Tagging Velocimetry (MTV) measurements are used to explore the flow fields associated with wall region negative ∂u˜/∂y in a low Rθ turbulent boundary layer. Velocity and velocity gradient statistical profiles establish the present flow as a canonical flat plate boundary layer. Spatial correlations of ∂u/∂y in the (x, y) plane, and the probability of observing negative ∂u˜+/∂y+ exceeding a negative threshold of −0.25 reveal the highly significant presence of negative ∂u˜/∂y in the region 25 ≤ y+ ≤ 35. Examination of the instantaneous flow fields underlying the conditional pdf indicates that there are two primary contributing motions: (i) streamwise shear layers and (ii) compact regions containing ±∂u˜/∂y. The importance of these motions to wall region turbulence production is discussed.

scholarly journals Photoisomeric molecular tagging velocimetry with CCVJ

2021 ◽  
Vol 6 (4) ◽  
Author(s):  
Markus J. Schmidt ◽  
Benno Käslin ◽  
Thomas Rösgen
Keyword(s):  
Molecular Tagging Velocimetry ◽  
Molecular Tagging

Optimising the Transfer Alignment of Weapon INS

2003 ◽  
Vol 56 (2) ◽  
pp. 323-335 ◽  
Author(s):  
Paul D. Groves
Keyword(s):  
Inertial Sensor ◽  
Integrated Navigation ◽  
Velocity Measurements ◽  
Transfer Alignment ◽  
Navigation Solution ◽  
Alignment Technique ◽  
Alignment Process ◽  
Using Data ◽  
Design Options ◽  
Better Than

Transfer alignment is the process of initialising and calibrating a weapon INS using data from the host aircraft's navigation system. To determine which transfer alignment technique performs best, different design options have been assessed, supported by simulation work. The dependence of transfer alignment performance on environmental factors, such as manoeuvres, alignment duration, lever arm and inertial sensor quality has also been studied. ‘Rapid’ alignment, using attitude as well as velocity measurements was found to perform better than ‘conventional’ techniques using only velocity. Innovative developments include the estimation of additional acceleration and gyro states and estimation of force dependent relative orientation, which has enabled robust alignment using wing rock manoeuvres, which do not require the pilot to change trajectory. Transfer alignment has been verified in real-time by flight trials on a Tornado aircraft. In addition, techniques have been developed to prevent transients in the aircraft integrated navigation solution following GPS re-acquisition after an outage of several minutes from disrupting the transfer alignment process.

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