SOLUTION SHEETFlowExplorer LDA systems

High performance – factory aligned and calibrated

FlowExplorer 3D LDA system

Pre-aligned and calibrated LDA solution for flow velocity measurements

Laser Doppler Anemometry (LDA) is an optical technique ideal for non-intrusive 1D, 2D
and 3D point measurement of velocity and turbulence in a wide range of fluid dynamics
applications.
The FlowExplorer optical transceiver is turn-key and uses compact lasers and Bragg
cells integrated into the stable and robust design. With a range of laser powers up to500 mW per velocity component, the FlowExplorer can be configured to meet the mostdemanding applications as well as those with limited budgets. The system is very easy toset up due to the factory aligned and calibrated optics. The calibration data are loaded
into the BSA Flow software package providing the most accurate results directly in
velocity units (m/s or ft/s).

Key benefits•

Factory aligned and turn-key operation for easy and fast setup.

•Each unit and lens is supplied with a calibration certificate to better than 0.11%•1-, 2- and 3 velocity component configurations•

Measurement distances from 150 mm to 750 mm•

On-line results (moments, histograms, etc.) thanks to real-time processing•

Extensive graphics and data exchange features•

Real-time system monitor display of signals, validation, data rate•Wifi, LAN or USB connection to PC•

Can be used as phase Doppler transmitting optics for particle sizing

The FlowExplorer LDA solution in brief
The LDA method uses the Doppler effect which occurs when laser
light is scattered from seed particles in a gas or liquid flow. Inside theFlowExplorer, a laser beam is split in two and then focused to a point toform a measurement volume. The Doppler shifted scattered light of eachparticle passing the measurement volume is collected and then sent to thesignal processor to determine their velocity.
The main benefits of LDA over other flow velocity measurement methods
include; optical technique does not disturb the flow, the transfer function
is linear and can be determined to high accuracy, small measurement
volumes are possible, high frequency response possible in well seededflows, and the absolute accuracy of the measurement results areunmatched due to calibrated Doppler constant and signal processor
performance.
The solution is based on three core components: optics, signal processor,and software.
Configurations for one, two or three velocity component measurements
are available with up to 500 mW laser power per wavelength. Even insystem configurations for measuring all three velocity components, thesame laser power is available for all three wavelengths, which ensuressimilar signal quality for all the velocity components.

LDA FlowExplorer system –Standard 1D, 2D and 3D FlowExplorer LDA configurations

OpticsCalibrated LDA solution
Since the optical transceiver is factory aligned and calibrated, theFlowExplorer LDA system is the ideal solution for applications requiring
documentation of the measurement uncertainty.
The velocity calibration uncertainty is 0.11% (coverage factor 2). The velocity
resolution is better than 0.002% of the chosen velocity range.
1D and 2D systems have a single optical head with one or two lasers,
connected to a BSA processor with one or two channels. The laser output
powers in the FlowExplorer DPSS are controlled from the BSA Flow software.
A 3D setup requires an additional FlowExplorer 1D unit as well as an additional velocity channel in the BSA processor. To align the two FlowExplorer
optical heads for overlapping measurement volumes, the 1D and 2D units
are mounted on adjustable supports on a common aluminium rail. A pinholealignment tool is supplied to ensure that both measurement volumes
overlap to high accuracy.
Page 2Processor
Fast & powerful all-in-one processor
The BSA F600 processor is a fast and powerful all-in-one processor. With
Ethernet, wifi and USB interfaces included, the processor can be connected
to a PC via a local area network, wireless or cabled. In large facilities orwhere remote access is required, these features make it easy to have theprocessor near the experiment and separate the PC at a long distance away
for safety and/or convenience.
The processor’s 120 MHz bandwidth covers a wide velocity range, up toseveral hundred m/s depending on the optical configuration.
System setup is very easy and user friendly: the setup is done directly in
velocity units, based on a center velocity and a velocity span value.
The processor software includes an on-line signal monitor which provides
the user with real-time information about signal quality, data rate,validation, coincidence between channels, PM sensitivity, and anode current.
This results in a powerful tool for optimizing the user adjustable parameters
during set-up and monitoring of measurement results.
For more details on the signal processor, please refer to the data sheet on“Burst Spectrum Analyzer (BSA)” available at our website.

BSA F600 Processor

Data Analysis
The most flexible and comprehensive software for LDA measurements
The BSA Flow software is comprehensive, easy to use, and includes
extensive graphics and data exchange features. The system setup including
the optical configuration as well as processor settings is controlled via thesoftware. Tools are provided which enables user-defined data analysis anddisplay, which is dynamically updated during measurements.
Data analysis can be customized with a built-in Calculation module as well as
a MatLab link for ultimate flexibility. Graphical output includes vector plots,
2D line and scatter plots, and 3D plots. Graphic results can be transferred
to a measurement report in pdf or HTML format. Numerical output includes
binary, ASCII, MS Excel, and TecPlot formats.
For further details on the software performance, please refer to the data
sheet on “BSA Flow Software” available at our website.

FlowExplorer LDA configurations
The FlowExplorer LDA solution is being offered in the following 1D, 2D and3D standard configurations. Other power options are available on request.
Optics1D

660 nm 70 mW
532 nm 100 mW
532 nm 150 mW
532 nm 300 mW
532 nm 500 m

2D660/785 nm 70/70 mW
532/561 nm 100/100 mW
532/561 nm 150/150 mW
532/561 nm 300/300 mW
532/561 nm 500/500 mW

3D

532/561/660 nm 100/100/100 mW
532/561/660 nm 150/150/150 mW
532/561/660 nm 300/300/300 mW
532/561/660 nm 500/500/500 mW

Processor

Software

BSA F600(120 MHz max.
frequency)

BSA Flow Software
Advanced Graphics
add-onOptions
The FlowExplorer system offers several options to meet the requirementsof the application. The options include:
Page 3

BSA Flow with Advanced Graphics add-on

Beam Expanders: Improve the signal quality (SNR) and reduce themeasurement volume size especially at longer measurement distances.
Optics mounts: adjustable supports for rotating a FlowExplorer headaround an axis perpendicular to its optical axis (panning) as well as forfine-adjustable pan, tilt and translation are available. For 3D systems, oneof each is required to align the two FlowExplorer heads for overlap of theirmeasurement volumes.
Processors: A wider velocity range can be covered using the BSA F800
upgrade which offers 200 MHz max. frequency allowing for measurementsof supersonic velocities with some optical configurations.
Software: Spectrum/Correlation Add-on, Cyclic Phenomena Add-on,
Scripting and MATLAB link Add-on, LIF and Parametric Analysis Add-on.
Traverse: A software controlled automatic traversing mechanism with 2D or
3D capability for flow mapping can be added to the system. Several standard
traverse controllers are supported in the software. For further details on thesoftware performance, please consult separate data sheet on our website.
Seeding: For air flows a range of liquid droplet and solid particle seeders areavailable. For liquid flows, we offer a variety of seeding particles. Please see
separate data sheets on our website.

Technical specifications
OpticsLaser
Laser power
Laser wavelength
Focal length
Optics weight(excl. laser controller)

FlowExplorer

FlowExplorer DPSS

Diode70

DPSS
100, 150, 300, 500

660/785 nm (1D/2D)

532/561/660 nm (1D/2D/3D)

150, 300, 500, 750

5 kg

Processor

BSA F600

Max. input frequency
Velocity range*)
Data rate
Resolution

120 MHz432 m/s

12 kg

BSA F800

200 MHz798 m/s>100,000 bursts/sec>16 bits*) depends on the optics, example for 60 mm probe with 500 mm focal length, 532 nm
wavelength.
SoftwareFeatures

BSA Flow

Online oscilloscope display of signals
Online display of data validation, data rate, coincidence
rate, photomultiplier anode current
Set up of BSA processor
Acquisition of data from BSA,
Control of traversing system
Statistics of results (mean, RMS, Skewness and Flatness)
Listing of results
Set up of analysis sequences
Export of data

Advanced Graphics
Add-onX-Y plots, vector plots, 3D plots, velocity profile plots

Solution Sheet SS_0492_v4. Subject to change without notice. Copyright © 2020.
Dantec Dynamics. All Rights Reserved. www.dantecdynamics.com