A new hybrid PTV algorithm in which a linear transformation was adopted, was constructed and its performances were validated. For the performance test, a set of numerical data on the Taylor-Green vortex flows was used. Using the data sets, artificial images were generated. In the test, the constructed hybrid PTV algorithm showed the best performance in the case where the particle number density was more than 4,000.
In order to validate the applicabilities of the constructed hybrid PTV algorithm, it was used for the measurements of the rectangular wake flows. Further, the conventional PIV and PTV techniques were used for the measurements of the same flow fields for comparison.
The vortical structures of the rectangular wake flows were compared with those obtained by the conventional PIV, a PTV technique (2-frame match probability), and by the constructed hybrid PTV algorithm.
A numerical simulation (CFD) was carried out for the same rectangular wake flows in order to compare the results with those obtained by the PIV, the PTV, and the constructed hybrid PTV algorithm through which it was verified that the pressure distribution at the rear part of the S type blade was much more uniform than those of A and SE models. This implies that the S type loses much more kinetic energy in the blade wake. This result was affirmed by electric power[W] meter measurements.
It was shown that the constructed hybrid PTV algorithm can be intensively used for the flow measurements of the free- horizontal-axis tidal power generation system.
Following is the structure of this paper:
In the first chapter, the research background and the purpose of the paper were mentioned.
In the second chapter, the principles of the PIV and PTV techniques were mentioned, and the newly constructed hybrid PTV algorithm was explained in detail. The results of the performance test on the constructed hybrid PTV algorithm were mentioned.
In the third chapter, an experiment on a rectangular wake was carried out in order to evaluate the performance of the constructed hybrid PTV algorithm. The results by the gray-level cross-correlation PIV and the 2-frame based PTV were also discussed for comparison with those obtained by the constructed hybrid PTV algorithm.
In the fourth chapter, a practical application of the constructed hybrid PTV algorithm was made. The flow features around the blades of the free-horizontal-axis tidal power generation system were investigated.
Lastly, summaries were made emphasizing the benefits of the constructed hybrid PTV algorithm for industrial applications. it was used for the measurements of the vortical structures of a free- horizontal-axis tidal power generation system. In the tests, three different models (A, S, SE) were used, and the measured velocity was used for constructing the velocity diagram based upon the momentum theory.
The results attested that the SE model showed the highest output power at the same blade angles among A, S and SE models. Further, it showed that the SE model showed good performances of power generation under fast current speeds and the S model showed good performances under slow current speeds. Using the same shape model, higher blade angle showed higher power generation.
The pressure fields were calculated using the velocity vector fields through which it was verified that the constructed hybrid PTV algorithm results showed better compatibility with those obtained by the CFD simulation.