scholarly journals Development of the method of laser Doppler anemometry for diagnostics of turbulent flows at high speed

2021 ◽  
Vol 2119 (1) ◽  
pp. 012110
Author(s):  
M R Gordienko ◽  
I K Kabardin ◽  
V G Meledin ◽  
A K Kabardin ◽  
M Kn Pravdina ◽  
...  
Keyword(s):  
Turbulent Flows ◽  
Flow Rate ◽  
High Speed ◽  
Velocity Vector ◽  
Laser Doppler Anemometry ◽  
Laser Doppler ◽  
Local Flow ◽  
Positioning Device ◽  
Measurement Area ◽  
Measuring Unit

Abstract The aim of the work was to develop a laser Doppler anemometry method for high-speed turbulent aerodynamic flow diagnostic. As a result, this allowed us to measure two projections of the velocity vector in the range of 0.1 - 400 m/s with a relative error not exceeding 0.5%. The measurement area was 0.1x0.1x0.5mm. The positioning device moved the measuring unit in the area of 250 x 250 x 250 mm with an accuracy of 0.1 mm. This method also provides the ability to measure local flow rate fluctuations.

scholarly journals Developing the laser doppler anemometry method for the diagnostics of kinematic parameters of a turbulent flow in the near wall region

2021 ◽  
Vol 2057 (1) ◽  
pp. 012096
Author(s):  
V G Meledin ◽  
S V Dvoinishnikov ◽  
I K Kabardin ◽  
A S Chubov ◽  
G V Bakakin ◽  
...  
Keyword(s):  
Velocity Vector ◽  
Laser Doppler Anemometry ◽  
Laser Doppler ◽  
Wall Region ◽  
Kinematic Parameters ◽  
Local Flow ◽  
Positioning Device ◽  
Measurement Area ◽  
Measuring Unit ◽  
Near Wall

Abstract The aim of the work is to develop a laser Doppler anemometry method for diagnosing turbulent aerodynamic flows in the near wall region. This will enable measuring two projections of the velocity vector in the range of 0.001 … 400 m/s with a relative error not exceeding 0.1%. The measurement area is 0.1×0.1x0.5mm. The positioning device allows moving the measuring unit in the area of 250×250x250 mm with an accuracy of 0.1 mm. This method also provides the ability to measure local flow rate fluctuations.

Effect Of The Rib Inclination Angle On Liquid Film Spreading Over The Structured Surface

2015 ◽  
Vol 10 (1) ◽  
pp. 42-49
Author(s):  
Aleksandr Pavlenko ◽  
Oleg Volodin ◽  
Vladimir Serdyukov
Keyword(s):  
Liquid Film ◽  
Flow Rate ◽  
Inclination Angle ◽  
High Speed ◽  
Film Flow ◽  
Complex Geometry ◽  
Experimental Studies ◽  
Local Flow ◽  
Structured Packing ◽  
Film Spreading

Results of experimental studies on hydrodynamics of the film flow of liquid nitrogen over the surface of the single elements of structured packing are presented. The effect of inclination angle of the large ribs and perforation on the zones of liquid film spreading over the corrugated surface with microtexture at different Reynolds numbers of the film is shown based on a comparison of experimental data. It is shown that the angle of large rib inclination has a significant influence on redistribution of the local flow rate of liquid flowing on the surface with complex geometry. Analysis of results of the high-speed video revealed that in a vicinity of the vertical lateral edges of corrugated plates, the intense rivulet flows are formed, including those with separation from the film flow surface. This negative factor can lead to significant liquid accumulation and flow near the vertical edges of the structured packing and on the inner wall of the heat exchanging apparatuses and, finally, to a significant increase in the degree of maldistribution of local liquid flow rate over the crosssection, for instance, of the distillation columns.

scholarly journals Advanced Laser-Based Techniques for Gas-Phase Diagnostics in Combustion and Aerospace Engineering

2017 ◽  
Vol 71 (3) ◽  
pp. 341-366 ◽  
Author(s):  
Andreas Ehn ◽  
Jiajian Zhu ◽  
Xuesong Li ◽  
Johannes Kiefer
Keyword(s):  
Gas Phase ◽  
Turbulent Flows ◽  
High Speed ◽  
Rayleigh Scattering ◽  
Dynamic Range ◽  
Laser Doppler Anemometry ◽  
Short Pulse ◽  
High Repetition Rate ◽  
Aerospace Engineering ◽  
Spectroscopic Techniques

Gaining information of species, temperature, and velocity distributions in turbulent combustion and high-speed reactive flows is challenging, particularly for conducting measurements without influencing the experimental object itself. The use of optical and spectroscopic techniques, and in particular laser-based diagnostics, has shown outstanding abilities for performing non-intrusive in situ diagnostics. The development of instrumentation, such as robust lasers with high pulse energy, ultra-short pulse duration, and high repetition rate along with digitized cameras exhibiting high sensitivity, large dynamic range, and frame rates on the order of MHz, has opened up for temporally and spatially resolved volumetric measurements of extreme dynamics and complexities. The aim of this article is to present selected important laser-based techniques for gas-phase diagnostics focusing on their applications in combustion and aerospace engineering. Applicable laser-based techniques for investigations of turbulent flows and combustion such as planar laser-induced fluorescence, Raman and Rayleigh scattering, coherent anti-Stokes Raman scattering, laser-induced grating scattering, particle image velocimetry, laser Doppler anemometry, and tomographic imaging are reviewed and described with some background physics. In addition, demands on instrumentation are further discussed to give insight in the possibilities that are offered by laser flow diagnostics.

Traceable Flow Rate Measurements With a Very Low Uncertainty Using Laser Doppler Anemometry

2017 ◽  
Author(s):  
Markus Juling ◽  
Jonas Steinbock ◽  
Andreas Weissenbrunner
Keyword(s):  
Flow Rate ◽  
Laser Doppler Anemometry ◽  
Volume Flow Rate ◽  
Primary Standard ◽  
Volume Flow ◽  
Laser Doppler ◽  
Maximum Deviation ◽  
Flow Profile ◽  
Rate Measurement ◽  
Flow Rate Measurement

Precise volume flow rate measurements are very important for various industrial applications. Here, one problem is that the service conditions of a flow meter used in the field differ significantly from the conditions present during calibration. The working conditions such as the pressure, the temperature and the flow profile greatly increase the uncertainty of the flow rate measurement. To address this problem, a new laser-optical flow rate standard (LFS) was developed at the Physikalisch-Technische Bundesanstalt (PTB) that allows flow meters to be calibrated on site, thus greatly reducing the uncertainty of the flow rate measurement. For the LFS, the velocity profile within the pipe is measured with laser Doppler anemometry (LDA). The profile is then integrated to calculate the volume flow rate. Various improvements to LDA have made it possible to measure the flow rate with an uncertainty of less than 0.15 % (k = 2). A comparison of the LFS with the primary standard for thermal energy at PTB, which has an uncertainty of less than 0.04 % (k = 2), revealed a maximum deviation of 0.07 % for Reynolds numbers from 105 to 106, thus verifying the uncertainty of the LFS.

Uncomplicated Setting Apparatus for Measurement of Fluid Flow Rate Using Laser Doppler Technique: Physics Teaching

2013 ◽  
Vol 770 ◽  
pp. 366-369
Author(s):  
Chatchalong Apiputikul ◽  
Kheamrutai Thamaphat ◽  
Monrudee Ranusawad ◽  
Pichet Limsuwan
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Doppler Shift ◽  
Laser Doppler Anemometry ◽  
Scattered Light ◽  
Fluid Velocity ◽  
Water Flow Rate ◽  
Processing System ◽  
Laser Doppler ◽  
Single Observation

Laser Doppler velocimetry (LDV) or laser Doppler anemometry (LDA) is the technique of using the Doppler shift in a laser beam to determine the fluid velocity. In this work, dual beam mode (two incident beams, single observation location) was selected to use. A cost effective and easy module for measurement of water flow rate was designed and constructed. A He-Ne laser with a wavelength of 632.8 nm was used as a light source. The laser was passed through a beam splitter and divided into two beams with identical intensity and coherence. Subsequently, the two laser beams travelled to a focusing lens with a focal length of 100 mm and focused on a center of water flow channel in quartz cuvette with a dimension of 1 × 1 × 5 cm3. The beam angle was set at 4.96°. When the seeding particles, bubbles and microorganism in water, were moving through the intersection point of two beams, the light was scattered. The scattered light was collected by photodetector connected to processing system. The frequency of scatterred light is shifted according to the Doppler shift relations due to effect of Rayleigh scattering. The water flow rate can be calculated from Doppler shift frequency.

Consecutive-Photo Method to Measure Vapor Volume Flow Rate During Boiling From a Wire Immersed in Saturated Liquid

1998 ◽  
Vol 120 (3) ◽  
pp. 561-567 ◽  
Author(s):  
C. N. Ammerman ◽  
S. M. You
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Measurement Technique ◽  
High Speed ◽  
Laser Doppler Anemometry ◽  
Volume Flow Rate ◽  
Nucleate Boiling ◽  
Volume Flow ◽  
Bubble Velocity ◽  
Vapor Flow

A photographic measurement technique is developed to quantify the vapor volume flow rate departing from a wire during boiling. The vapor flow rate is determined by measuring the volume of bubbles after departure from the boiling surface in consecutive frames of high-speed video. The measurement technique is more accurate and easier to implement than a previously developed photographic/laser Doppler anemometry (LDA) method. Use of the high-speed camera in place of a standard video camera eliminates the requirement for LDA-acquired bubble velocity measurements. The consecutive-photo method requires relatively few video images to be analyzed to obtain steady-state vapor volume flow rates. The volumetric flow rate data are used to calculate the latent heat transfer and, indirectly, sensible heat transfer which comprise the nucleate boiling heat flux. The measurement technique is applied to a 75-μm diameter platinum wire immersed in saturated FC-72.

scholarly journals Investigating High Turbulent Flows by Laser Doppler Anemometry

Helix ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 5358-5364
Author(s):  
Ilnar F. Ramazanov ◽  
Farit F. Ramazanov ◽  
Leysan F. Ryadninskaya
Keyword(s):  
Turbulent Flows ◽  
Laser Doppler Anemometry ◽  
Laser Doppler

Changes in Carotid Artery Flow Velocities after Stent Implantation: A Fluid Dynamics Study with Laser Doppler Anemometry

2003 ◽  
Vol 10 (2) ◽  
pp. 275-284 ◽  
Author(s):  
Oliver Greil ◽  
Gottlieb Pflugbeil ◽  
Klaus Weigand ◽  
Wolfgang Weiß ◽  
Dieter Liepsch ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Flow Rate ◽  
Rate Ratio ◽  
Laser Doppler Anemometry ◽  
Flow Behavior ◽  
Laser Doppler ◽  
Flow Rate Ratio ◽  
External Carotid ◽  
Flow Profile ◽  
Separation Zones

Purpose: To study the influence of stent size and location on flow patterns in a physiological carotid model. Methods: Wallstents were positioned in silicon models of the carotid artery at various locations: 2 stents appropriately sized to the anatomy were placed in (1) the internal carotid artery (ICA) and (2) the ICA extending completely into the common carotid artery so as to cover the external carotid artery (ECA) orifice. Another 2 stents were placed in the ICA extending (1) partially and (2) completely into the bulb to simulate stent displacement and disproportion between stent size and the original vessel geometry. Measurements were performed with laser Doppler anemometry (LDA) using pulsatile flow conditions (Reynolds number=250; flow 0.431 L/min; ICA:ECA flow rate ratio 70:30) in hemodynamically relevant cross sections. The hemodynamic changes were analyzed with 1-dimensional flow profiles. Results: With the stent in the ICA, no changes of the normal flow profile were seen. For stents positioned in the ICA and extending partially or completely into the carotid bulb, the flow behavior was affected by the resistance of the stent to flow in the ECA. Hemodynamically relevant disturbances were seen in the ICA and ECA, especially in the separation zones (regions along the walls just after a bifurcation, bend, or curve). The ICA:ECA flow rate ratios shifted from 70:30 to 71.3:28.7 and from 70:30 to 75.1:24.9, respectively, in the 2 malpositioned stent models. With the stent placed in the ICA extending completely into the CCA, the ICA:ECA flow rate ratio shifted from 70:30 to 72.4:27.6. In this configuration, there were no notable flow changes in the ICA, but a clear diminishing of the separation zones in the ECA separation zones. Conclusions: Anatomically correct positioning of appropriately sized stents does not lead to relevant flow disturbances in the ICA. In the ECA, depending on the position, size, and interstices of the stent, the physiological flow was considerably disturbed when any part of the stent covered the inflow of the vessel. Disturbances were seen when the stent was positioned into the bulb. For clinical application, stent location and size must be carefully determined so that the stent covers the bifurcation completely or is in the ICA only.

Spray Generated by an Airblast Atomizer at High-Pressure Conditions

2007 ◽  
Author(s):  
Feras Z. Batarseh ◽  
Ilia V. Roisman ◽  
Cam Tropea
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
High Speed ◽  
Velocity Vector ◽  
Ambient Pressure ◽  
Air Flow ◽  
Water Flow Rate ◽  
The Other ◽  
Air Flow Rate ◽  
Spray Visualization

We present an experimental investigation of a spray generated by an airblast atomizer. Experiments have been performed in a pressure chamber equipped by transparent windows allowing an optical access to the spray. Several techniques of spray investigation have been applied: spray visualization using the high-speed video system, spray visualization and instantaneous velocity measurements using the PIV technique, spray velocimetry and sizing using the IPI and phase Doppler instruments. Phase Doppler instrument has been used to characterize the droplets in the spray: their diameter, two components of the velocity vector. Also the integral parameters of the spray, such as the local volume flux density, have been characterized. We conduct a parametric study of the effect of the ambient pressure, the air flow rate and the water flow rate on an atomized spray. Measurements at different radial locations in the spray and in two planes were performed. The measurements in these two planes allow one to determine the distributions of all the three components of the average drop velocity vector: axial, radial and azimuthal. PDA measurements show that atomized spray is sensitive to any change in the studied parameters. For example, increasing air flow rate from 20 SCMH to 45 SCMH and keeping same water flow rate and pressure, leads to an increase in all velocity components and also to a change in droplets diameters. On the other hand, keeping constant pressure and air flow rate and increasing water flow rate from 0.7 to 1.4 l/hr, leads to an increase in water droplets sizes and the axial velocity component, whereas the other velocity components show a non uniform change. Moreover, increasing the ambient pressure leads to the growth of the spray velocity and drops diameters.

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