The Hyvärinen Project (Standard Cirrus)

Jari Hyvärinen and his daughter Ann have undertaken a project to understand and model the operation of a full deturbulator configuration, as tested by Johnson in 2006. This involves discovering the aeroelastic modes of deturbulator panels, the near and far effects of leading-edge, rear-facing steps, such as we have constructed using thin tapes, and the overall wing flow dynamics resulting from these modifications.

To model the fluid dynamics over the tape will require a 3D model using a Navier-Stockes Equation solver with a good Large Eddy Simulation (LES) turbulence model. Jari has access to his brother in law's FlowPhys software for this. As a part of a proposed UK funded research project, he plans to include a study of the dynamics of the leading edge tape that Jari and several pilots are flying with and testing.

Jari is using his own linear algorithms for the aeroelastic deturbulator panel work. These are in his LINFLOW software package that is available commercially through his company ANKER-ZEMER Engineering AS, in Vintrosa, Sweden. He will be presenting a paper at a future AIAA conference when their initial work reaches an appropriate milestone. In the meantime, however, they have written a preliminary report of their progress. This is in the PDF file

Prelininary Investigations
Preliminary Investigations of Aeroelastic Panel Vibration with respect to Performance Boost of Airplane Wings. The work reported in that document occured over the summer of 2011 and produced really great data for correlating with their LINFLOW analysis. For example, pictured here is a frequency spectrum from measurements at 100 kph (54 kts)on the top wing surface with a tape wrapped around the leading edge of the wing.

An example of results for a 3D section of the cirrus wing using FlowPhys is show here. This picture shows iso-pressure surfaces in the domain around the wing.

If the measured spectrum can be produced with the LES software, Jari will know that the calculated fluid dynamics describes the flow passing over the actual wing with the tape installed. This is an imporant step.

The other side of the problem is approached with LINFLOW which is an areroelastic software package that enables Jari to study the dynamics of the deturbulator panel membrane, as it is influenced by the flow passing over it. By knowing the spectrum of the flow at specific velocities, Jari has used LINFLOW to study which membrane modes are most sensitive to excitation by the spectrum measured at the same velocity. A mode at 100 kph was found that also appeared visually in a video recording. This is shown below.

What remains is to measure the difference between the velocity profile leaving the clean wing and the velocity profiles for configurations with a leading edge tape alone and with both a tape and a deturbulator panel. If these measurements continue to give as clear results as the ones we have completed, then Jari should be in a possition to write a paper explaining what makes this work and how well it works.

If everything is ok at that point, then it will be time to start investigating which parameters influence total system behavior and also begin working on the next generation system for boosting performance over a wider velocity range.

It should be clear that the above tasks are by no means simple. On the other hand Jari is convinced that it can be done.

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