Information on the Particle Dynamics Analysis (PDA) measurements

Transcription

1 Information on the Particle Dynamics Analysis (PDA) measurements Contents Contents... Introduction... Properties of the PDA System... Measurement principles []... Information on the variables in each column of the exported data... Moments (one time statistics)... Diameter statistics... Distribution... Introduction In this short description some details can be found about the Particle Dynamics Analysis measurements. The system parameters are put down in tabular form, the measurement principles are shown in an image with a link leading to the webpage of Dantec Dynamics, where a thorough description can be found. An important issue is the meaning of the single columns of the exported data, which can also be found in the last section. For further questions, please contact the author: bordas@ovgu.de. Properties of the PDA System Laser Water cooled Argon-ion Coherent E70 Used wave length. nm Applied power W (@ whole wavelength spectrum) Transmitting optics Shift frequency 0 MHz Focal length 600 mm Beam diameter. mm Beam spacing 9. mm Beam expansion ration.97 Probe volume diameter mm length.0 mm Number of fringes 8 Fringe spacing.6 μm Beam half angle φ/.76

2 Receiving optics Receiver type Fiber PDA Focal length 800 mm Expander ratio Fringe direction positive Scattering angle 6 Scattering mode nd order refraction High voltage level of the first PM 00 V Signal gain 0 db Aperture mask Mask A Spherical validation band % Phase factor P to P.06 deg/µm Phase factor P to P 0.08 deg/µm Eff. slit width 0.60 Table : System parameters of the PDA system Measurement principles [] Particle Dynamics Analysis (PDA) is an optical technique to measure the size and velocity of spherical particles simultaneously. The measurements are performed on single particles, thus allowing detailed analysis of particulate flows. The distribution of statistical size and velocity moments in a flow field can be measured, as well as particle concentration and local size velocity correlation. The measurement point is defined by the intersection of two focused laser beams and the measurements are performed on single particles as they move through the sample volume. Particles thereby scatter light from both laser beams, generating an optical interference pattern. A receiving optics placed at a well chosen off axis location projects a portion of the scattered light onto multiple detectors. Each detector converts the optical signal into a Doppler burst with a frequency linearly proportional to the particle velocity. The phase shift between the Doppler signals from different detectors is a direct measure of the particle diameter. Advantages Size range from sub micron up to several millimeters Velocity range from zero to supersonic One, two or three velocity components simultaneously No calibration required Instantaneous and time averaged information High spatial and temporal resolution Non intrusive Detailed description of the measurement principle can be found here: Dantec Dynamics/LDV

3 Image : Measurement principles of the PDA [] Information on the variables in each column of the exported data Moments (one time statistics) X [mm] Y [mm] Z [mm] Date_Time Count{} Data Rate{} [#/s] x coordinate (parallel to the flow direction) y coordinate (perpendicular/horizontal) z coordinate (perpendicular/vertical) Date/time of the measurement Number of acquired samples Sample rate [#/s] Validation{} [%] Sample validation rate [%] LDA Mean [m/s] Mean velocity: [m/s] D Mean [um] Mean diameter: [µm]

4 LDA RMS [m/s] D RMS [um] LDA MeanConf [m/s] D MeanConf [um] LDA RMSConf [m/s] D RMSConf [um] Standard deviation of the instantaneous velocities: [m/s] Standard deviation of the instantaneous velocities: [µm] LDA AnodeCur [ua] Anode current in µa LDA Skew LDA Flat D Flat Confidence interval of the mean velocity [m/s] Confidence interval of the mean diameter [µm] Confidence interval of the standard deviation [m/s] Confidence interval of the standard deviation [µm] Skewness of the velocities: Flatness of the velocities: Flatness of the diameters: Diameter statistics X [mm] Y [mm] Z [mm] Counts x coordinate (parallel to the flow direction) y coordinate (perpendicular/horizontal) z coordinate (perpendicular/vertical) Number of acquired samples Spherical Validation [%] Spherical validation rate [%] D0 [um] Mean diameter: [µm] D0 [um] Surface area mean diameter: [µm] D0 [um] Volume mean diameter: D [um] Sauter mean diameter: D [um] De Brouckere mean diameter: Concentration [#/cm] U Flux [cm/cm/s] V Flux [cm/cm/s] Concentration per unit volume [#/cm³] U flux [cm³/cm²/s] V flux [cm³/cm²/s] [µm] [µm] May be erroneous, examination in progress

5 Distribution AT [ms] TT [us] LDA [m/s] D [um] Arrival time of the tracers in [ms] Transit time of the tracers [µs] Instantaneous velocity [m/s] Diameter of the particle [µm] Here the measurement coordinates and the date/time of the measurements can also be found in the header of the single files. The data columns of the recently exported files can be different, because of a software update. The meaning of the actual column is always explained in the column header. Magdeburg, July 009.