��Integrated solutions in Laser Doppler Anemometry Integrated LDA solutions Laser Doppler Anemometry (LDA) is With the introduction of the new FiberFlow and FlowLite optics the ideal measurement technique for processors and the enhancements �% High-accuracy probes the non-intrusive investigation of velo- that have been added to BSA Flow �% Probe diameters of 14, 27, 60, 85 city and turbulence in gas or liquid Software, Dantec Dynamics main- and 112 mm flows. The applications described in tains its leading position in flow this brochure demonstrate the wide measurement. �% Wide choice of front lenses, beam relevance of LDA across the spectrum With additional modules, BSA expanders and probe supports for of scientific and industrial research. processors can be upgraded to per- maximum application flexibility form simultaneous measurement of particle size and velocity using Typical LDA applications Particle Dynamics Analysis (PDA) Traverse systems optics. �% Aerodynamics �% Modular traverse systems �% Hydrodynamics compatible with the LDA optics Combined with Dantec Dynamics and software �% Rotating machinery BSA Flow Software package and FiberFlow or FlowLite transmitting/ �% Combustion processes receiving optics, these new proces- �% Verification of CFD models Seeding generators sors offer total LDA solutions. �% A range of seeding generators Dantec Dynamics LDA systems set using smoke, droplets or powders the standard and are used throughout BSA Flow Software is available the world by both research scientists �% Simplified system monitoring and industrial R&D engineers. Dantec Dynamics completely new �% On-line Doppler Burst Monitor Burst Spectrum Analysers incorporate �% End results on-line, using analysis the very latest in DSP technology and sequences digital filtering. Every element has been �% User-defined analysis sequences newly developed, so these processors can truly be described as state-of-the- �% Project templates art. �% Fast access to data �% Wizards for quick experiment set-up For more information about system components, please visit our web site www.dantecdynamics.com/literature Dantec Dynamics completely new Burst Spectrum Analyser, and the BSA Flow Software package. 2 The principles of Laser Doppler Anemometry A) LDA is a non-intrusive optical C) The back-scattered light is cap- measurement technique for tured by the FiberFlow or FlowLite investigating velocities at a point in a transmission/receiving optics flow. LDA can be used in any gas or D + E) A photomultiplier converts liquid flow with optical access to the the light intensity fluctuations to elec- measurement point provided that trical signals which are in turn con- micron-sized seeding particles are verted to velocity information in the present. BSA processor. The frequency of the B) The measurements are performed flashing light (Doppler frequency) is at the intersection of two laser beams, proportional to the flow velocity at the where there is an interference fringe measurement point. pattern of alternating light and dark F) The processing results are handled planes. Seeding particles scatter the by the BSA Flow Software. Three com- light, which appears to flash, as the ponents of the velocity vector can be particles pass through the bright acquired simultaneously, depending planes of the interference pattern. on the system configuration. FlowLite system measuring three FiberFlow transmitting/receiving optics. components simultanously. Diameters of 14, 27, 60 and 112 mm. High-resolution traverse systems fully controlled by the BSA Flow Software package. 3 Aerodynamics Aerodynamic experiments are often Detailed information about the velocity Airflows in passenger undertaken in wind tunnels. The field around the object under test compartments objectives are measuring and reducing can be obtained by traversing the LDA LDA is well suited to the measuring of drag, minimising energy consumption, measurement point. the complicated flow patterns in reduction of wind noise, optimisation of passenger compartments because of cooling and validation of Computational its ability to measure flow reversals. Car-body aerodynamics Fluid Dynamics (CFD) code. In automotive testing, LDA is used both Applications include: to obtain information on the global flow field and to study details such as air- �% Car-body aerodynamics flow around mirrors, wheels and in the �% Airflows in passenger compart- engine compartment. ments �% Engine compartment flows �% Aircraft model testing �% Flows around helicopter rotors �% Airflows around buildings and other structures �% Turbulence research �% Industrial process flows Engine compartment flows The streamlined shape of modern cars allows little space in the engine com- partment for air cooling of the engine, making it all the more important for the radiator s cooling efficiency to be optimised. LDA is used to measure velocity profiles of the airflow passing through the radiator and can, for example, reveal flow reversals that reduce cooling efficiency. Flow field behind a car radiator. Investigating the aerodynamics of an Courtesy of Pininfarina, Italy. external rear-view mirror. Photo courtesy of DaimlerChrysler, Germany. 4 Aircraft model testing New aircraft designs are extensively tested with models in wind tunnels before full-scale prototypes are built. Flow separation and wing-tip vortices are among the flow details studied. Airflows around buildings and other structures Measurement of three velocity LDA measures flow reversals and three components around a model of a trans- velocity components, making it an port plane. Photo courtesy of ONERA, ideal method for studying the complex France. flows around ships, bridges, buildings and offshore structures. Flows around helicopter rotors Studies include the effect of different inflow characteristics and noise generation from the rotor blades. LDA measurements can be synchronised to the angular position of the helicopter rotor in order to obtain detailed flow- Measurements around the super- field information around the rotor structure of a ship model. blade. Photo courtesy of University of Bristol. Turbulence research LDA is used in a large variety of turbulence research applications, including CFD code validation. The wide velocity range, high temporal and spatial resolution and accuracy of the velocity measurement are important features for this work. Industrial process flows Measurement of air flow around a Optimisation of industrial processes helicopter rotor model. Photo courtesy of during the design phase is often University of Bristol. achieved through a combination of CFD and LDA experiments. Tasks include the avoidance of recirculation zones and the deposit of solids on walls. Experiment in a model wind tunnel. Studying the flow field in a cyclone model. 5 Hydrodynamics, rotating machinery and combustion Hydrodynamic experiments include the optimisation of the efficiency of fluid machinery, the avoidance of cavitation and the simulation of flows in rivers and along coasts, and many other applications. Applications include: �% Channel flows �% Pipe flows �% Sediment transport �% Mixing phenomena �% Ship hull design �% Cavitation studies on propellers/pump impellers �% Propulsion efficiency �% Wave research �% Coastal engineering Measurement in a hydrodynamic tunnel. Photo courtesy of ONERA, France. Channel flows Hydrodynamic channels and tunnels synchronisation with the angular posi- can be used to study aerodynamic Rotating machinery tion of the rotor. phenomena, because it is possible to During blade passage, the laser obtain similar Reynolds numbers at beams must be blocked in order to much lower flow velocities. Engines prevent saturation of the photo- multipliers. Dantec Dynamics BSA Improving efficiency and reducing Pipe flows processors have integrated synchroni- pollution are key research areas in sation outputs that can control an elec- Pipelines may erode as a result of engine development. The non-intrusive tro-optical shutter that blocks the laser turbulence created around welds. This LDA technique is very suitable for the beams during blade passages. turbulence is modelled and studied measurement of flows inside engine with LDA to avoid the development of cylinders. Velocity data are stamped dangerous leaks. with the crankshaft angle to resolve the Pumps Flowmeters are calibrated with fully engine cycle. To optimise pump efficiency, LDA is developed turbulence at the inlet. They used to improve both inlet-flow are, however, also often used in other Gas turbines geometry and the flow between pump conditions. LDA helps in developing an impeller blades. understanding of how non-ideal flow Studies of the intra-blade flow in gas characteristics at the inlet affect the turbines requires high temporal flowmeter reading. resolution, a high data-rate capability, large velocity bandwidth and Combustion Cavitation and propulsion efficiency of ship propellers Cavitation causes noise, reduced LDA is used in the improvement of efficiency and erosion of ship propeller combustion processes. A typical blades and impellers used in pumps, objective is to reduce the emission of mixers and water turbines. LDA and CO, hydrocarbons and NOx. PDA are used in cavitation tunnels to Applications include flame investiga- study such phenomena. The non- tions in engine research and efficiency intrusive technique enables measure- improvement in furnaces, burners and ment between the blades. An encoder stoves. attached to the impeller shaft can pro- vide angular position information that is stored along with flow velocity data, so that blade-to-blade velocity profiles can be obtained. Measurement of propeller-tip vortices using a 3-component LDA system. Photo courtesy of MARIN, the Netherlands. 6 Measurement in an engine using Laser Doppler Anemometry. Photo courtesy of AVL-List GmbH, Austria. Investigation of the flow between the Flow-field analysis in the reaction zone Measuring the velocity profile in the inlet impeller blades of a pump. Photo of a wood-burning stove. Photo courtesy of a flowmeter calibration rig. courtesy of Grundfos A/S, Denmark. of the University of Stuttgart, Germany 7 Increasing your knowledge Our business philosophy is based on openness. The ever increasing body of knowledge that we acquire is knowledge we share with our customers. With Dantec Dynamics as your business partner, you are ensured access to a full range of relevant and regularly updated information via our website. Why not take an initial look right now? It s just a click away at www.dantecdynamics.com Worldwide representation Sales and support offices in USA, Japan, Denmark, France, Germany and UK. Representatives in more than 30 countries. A list of representatives with contact information is available on www.dantecdynamics.com/contact/representatives DENMARK (main office) GERMANY Dantec Dynamics A/S Dantec Ettemeyer GmbH E-mail: [e-mail] E-mail: [e-mail] www.dantec-ettemeyer.com FRANCE Dantec Dynamics S.A. Dantec Dynamics GmbH E-mail: [e-mail] E-mail: [e-mail] UNITED KINGDOM Dantec Dynamics Ltd. E-mail: [e-mail] www.dantecdynamics.com USA www.dantec-ettemeyer.com Dantec Dynamics Inc. E-mail: [e-mail] JAPAN Dantec Dynamics K.K. E-mail: [e-mail] The specifications in this document are subject to change without notice. FiberFlow, Partners for Progress and Dantec Dynamics are trademarks of Dantec Dynamics A/S. Publication No.: 104-106-01