Update: 06/10/2005
There are many unresolved problems in flow analysis left: What are vortices, how do they roll up and dissipate? What is turbulence and what is its influence on technical flows? When taking into account that for instance a 10% decreased fuel consumption of a commercial aircraft can double the profit, it seems to be very important to get a better understanding of those aerodynamic influences. Therefore the development of novel theoretical simulation models and experimental visualization and measurement techniques is one of the main activities at the F.I.B.U.S. research institute.
A new flow visualization method, the " Flow Visualization Gun", has been developed and applied to different flow problems like vortex behaviour at helicopter rotors, wind induced waves on water surfaces, or air condition flow types. Theoretical models of integral type (Biot- Savart, Vortex-Lattice) have been developed for helicopter rotor flow and wind turbine flow.
Supersonic Turbine Rotor FlowVisualized by 4 Color Schlieren Technique |
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Helicopter Rotor FlowTip Vortex Interaction with Rotorblade, Visualized by Titanium Smoke, Color Enhanced by Imagev Analysis |
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Helicopter Forward FlightTip Vortex Path, visualized by Smoke Blown out of the Blade Tips. Slow Forward Flight: Advance Ratio is... µ = 0.1 |
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Helicopter Forward FlightTip Vortex Path, visualized by Smoke Blown out of the Blade Tips. Faster Forward Flight: Advance Ratio is... µ = 0.2 |
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Observation of vortex pairing and merging at hover with anhedral tip shapePath of a spiraling double tip vortex, visualized by theatre smoke injected into the flow. The video clip is half a rotor turn, so set your mpeg-viewer to "repeat" and see the rotor turn forever... In case of problems with your player please load the VMPEG player below! More information in: "Special Vortices at a Helicopter Rotor Blade", AHS journal vol 35, no 4, Oct. 1990 |
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Observation of vortex pairing due to asymmetrical vortex spacingPath of the tip vortices using different tip shape on the two blades of the rotor, one blade anhedral, the other blade dihedral. Due to the different spacing a vortex pairing and spiraling can be observed which is almost independent from instabilities by recirculation or other disturbances. It is half a rotor turn only, so there is a jump from one tip shape to the other in the video clip.... :-( In case of problems with your player please load the VMPEG player below!
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Load here your VMPEG Player (and other players): MPEG.ORG | ||
Load here your QuickTime Player for Mac, PC or UNIX |
Calculated flow field of two bladed helicopter rotor, using free wake analysis method | |
Roll-up of vortex filaments im the trailing vortex sheet of the rotor blade, using a vortex lattice technique |
Sorry, our computers are still busy finishing the flow calculations ;-)