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14 Krzysztof Olasek, Maciej Karczewski

6. RESULTS

In order to verify the proposed algorithm for lift force estimation on NACA0012, the results obtained by integrating solely the velocity-based flow field were compared to the results obtained from surface pressure integral over the airfoil's boundary. The latter is a standard procedurę for load estimation on closed-loop boundaries in all commercial CFD packages, including ANSYS CFX. The comparison is presented in Fig. 4. As it can be seen, a very good conformity was achieved. Not only the right distribution of the aerodynamic characteristics was obtained (trend of the linę and position of the critical stall angle), but also, quantitatively, the results show an exceptional agreement.

7. CONCLUSIONS

Analysis of the presented results confirms a high potential of the velocity-based lift calculations. Basing only on the velocity field around the airfoil, it is possible to calculate the aerodynamic loads. Agreement of the velocity-based calculations with the reference pressure-based values opens up a possibility to use the method for load estimation in non-invasive PIV flow measurements.

Presented results and findings should be treated as preliminary. There is still room for improvements. Futurę plans covers the following actions:

-    check the validity of the method for different types of airfoils,

-    test the algorithm for larger angles of attack where flow is unsteady,

aperiodic and, therefore, morę complicated,

-    improve and automate the integral curve size determination process especially for on-line measurement applications requiring fast response times,

-    perform tests for different shapes of integral curve (apart from

investigated rectangle),

-    introduce a program module for drag force coefficient calculations.

8. REFERENCES

1.    Olasek K., Karczewski M., Multi-Phase Modemisation of the Subsonic Wind Tunnel Oriented Towards Integration of CFD & Experiment. XX Fluid Mechanics Conference KKMP2012. 17-20 1X2012, 978-83-927340-8-6.

2.    Dobrev, I., Massouh, F. METHOD FOR EXTRACTING AIRFOIL DATA OF ROTATING BLADES. Orleans, France : s.n., 2011.

3.    Olasek K., Karczewski M., Witkowski D. Integrating CFD into Wind Tunnel Design . 14th International Symposium ofStudents and Young Mechanical Engineers "Advances in Chemical and Mechanical Engineering”. 2011, Vol. 2, pp. 129-138.